* agent: health checks: change long timeout behavior to use to user-configured `timeout` value [[GH-6094](https://github.com/hashicorp/consul/pull/6094)]
* api: Update filtering language to include substring and regular expression matching on string values [[GH-6190](https://github.com/hashicorp/consul/pull/6190)]
* connect: change router syntax for matching query parameters to resemble the syntax for matching paths and headers for consistency. [[GH-6163](https://github.com/hashicorp/consul/issues/6163)]
* connect: allow L7 routers to match on http methods [[GH-6164](https://github.com/hashicorp/consul/issues/6164)]
* connect: Fixed a bug that would prevent CA replication/initializing in a secondary DC from working when ACLs were enabled. [[GH-6192](https://github.com/hashicorp/consul/issues/6192)]
* connect: added a new `-bind-address` cli option for envoy to create a mapping of the desired bind addresses to use instead of the default rules or tagged addresses [[GH-6107](https://github.com/hashicorp/consul/pull/6107)]
BUG FIXES:
* connect: fix bug in service-resolver redirects if the destination uses a default resolver [[GH-6122](https://github.com/hashicorp/consul/pull/6122)]
* connect: resolve issue where `MeshGatewayConfig` could be returned empty [[GH-6093](https://github.com/hashicorp/consul/pull/6093)]
* connect: ensure local dc connections do not use the gateway [[GH-6085](https://github.com/hashicorp/consul/issues/6085)]
* agent: fix an issue that could cause a panic while transferring leadership due to replication [[GH-6104](https://github.com/hashicorp/consul/issues/6104)]
* **Connect Envoy Supports L7 Routing:** Additional configuration entry types `service-router`, `service-resolver`, and `service-splitter`, allow for configuring Envoy sidecars to enable reliability and deployment patterns at L7 such as HTTP path-based routing, traffic shifting, and advanced failover capabilities. For more information see the [L7 traffic management](https://www.consul.io/docs/connect/l7-traffic-management.html) docs.
* **Mesh Gateways:** Envoy can now be run as a gateway to route Connect traffic across datacenters using SNI headers, allowing connectivty across platforms and clouds and other complex network topologies. Read more in the [mesh gateway docs](https://www.consul.io/docs/connect/mesh_gateway.html).
* **Intention & CA Replication:** In order to enable connecitivty for services across datacenters, Connect intentions are now replicated and the Connect CA cross-signs from the [primary_datacenter](/docs/agent/options.html#primary_datacenter). This feature was previously part of Consul Enterprise.
* agent: Added tagged addressing to services similar to the already present Node tagged addressing [[GH-5965](https://github.com/hashicorp/consul/pull/5965)]
* raft: allow trailing logs to be configured as an escape hatch for extreme load that prevents followers catching up with leader [[GH-6186](https://github.com/hashicorp/consul/pull/6186)]
* agent: avoid reverting any check updates that occur while a service is being added or the config is reloaded [[GH-6144](https://github.com/hashicorp/consul/issues/6144)]
* auto-encrypt: fix an issue that could cause cloud retry-join to fail when utilized with auto-encrypt by falling back to a default port [[GH-6205]](https://github.com/hashicorp/consul/pull/6205)
* agent: make sure client agent rate limits apply when hitting the client interface on a server directly [[GH-5927](https://github.com/hashicorp/consul/pull/5927)]
* ui: fix service instance linking when multiple non-unique service id's exist on multiple nodes [[GH-5933](https://github.com/hashicorp/consul/pull/5933)]
* txn: Fixed an issue that would allow a CAS operation on a service to work when it shouldn't have. [[GH-5971](https://github.com/hashicorp/consul/pull/5971)]
* acl: fixed an issue that if an ACL rule is used for prefix matching in a policy, keys not matching that specific prefix can be deleted by a token using that policy even with default_deny settings configured [[GH-5888](https://github.com/hashicorp/consul/issues/5888)]
* agent: Fixed an issue where recreating a node using a different ID would prevent the new node from correctly joining. [[GH-5485](https://github.com/hashicorp/consul/pull/5485)]
* /watch: (note this only affects downstream programs importing `/watch` package as a library not the `watch` feature in Consul) The watch package was moved from github.com/hashicorp/consul/watch to github.com/hashicorp/consul/api/watch to live in the API module. This was necessary after updating the repo to use Go modules or else various other bugs cropped up. The watch package API has not changed so projects depending on it should need to only update the import statement to get their code functioning again. [[GH-5664](https://github.com/hashicorp/consul/pull/5664)]
* ui: Legacy UI has been removed. Setting the CONSUL_UI_LEGACY environment variable to 1 or true will no longer revert to serving the old UI. [[GH-5643](https://github.com/hashicorp/consul/pull/5643)]
* **Connect Envoy Supports L7 Observability:** We introduce features that allow configuring Envoy sidecars to emit metrics and tracing at L7 (http, http2, grpc supported). For more information see the [Envoy Integration](https://consul.io/docs/connect/proxies/envoy.html) docs.
* **Centralized Configuration:** Enables central configuration of some service and proxy defaults. For more information see the [Configuration Entries](https://consul.io/docs/agent/config_entries.html) docs
* cli: allow to add ip addresses as Subject Alternative Names when creating certificates with `consul tls cert create` [[GH-5602](https://github.com/hashicorp/consul/pull/5602)]
* agent: config is now read if json or hcl is set as the config-format or the extension is either json or hcl [[GH-5723](https://github.com/hashicorp/consul/issues/5723)]
* ui: Service Instances page redesign and further visibility of Connect Proxies [[GH-5326]](https://github.com/hashicorp/consul/pull/5326)
* ui: Blocking Query support / live updates for Services and Nodes, requires enabling per user via the UI Settings area [[GH-5070]](https://github.com/hashicorp/consul/pull/5070) [[GH-5267]](https://github.com/hashicorp/consul/pull/5267)
* ui: Finer grained searching for the Service listing page [[GH-5507]](https://github.com/hashicorp/consul/pull/5507)
* api: fix issue in the transaction API where the health check definition struct wasn't being deserialized properly [[GH-5553](https://github.com/hashicorp/consul/issues/5553)]
* agent: Fix an issue with registering health checks for an agent service where the service name would be missing. [[GH-5705](https://github.com/hashicorp/consul/issues/5705)]
* connect: fix an issue where Envoy would fail to bootstrap if some upstreams were unavailable [[GH-5499](https://github.com/hashicorp/consul/pull/5499)]
* connect: fix an issue where health checks on proxies might be missed by watchers of `/health/service/:service` API [[GH-5506](https://github.com/hashicorp/consul/issues/5506)]
* connect: fix a race condition that could leave proxies with no configuration for long periods on startup [[GH-5793](https://github.com/hashicorp/consul/issues/5793)]
* acl: fixed an issue that if an ACL rule is used for prefix matching in a policy, keys not matching that specific prefix can be deleted by a token using that policy even with default_deny settings configured [[GH-5888](https://github.com/hashicorp/consul/issues/5888)]
* Fixed a problem where `verify_server_hostname` was not being respected and the default `false` was being used. This problem exists only in Consul 1.4.3. (CVE-2019-9764) [[GH-5519](https://github.com/hashicorp/consul/issues/5519)]
* api: `/health/service/:service` blocking queries now only need a single goroutine regardless of number of instances in the service and watch channel which can massively reduce the number of goroutines on busy servers. [[GH-5449](https://github.com/hashicorp/consul/pull/5449)]
* api: Fixed a bug where updating node information wasn't reflected in health result index. [[GH-5450](https://github.com/hashicorp/consul/issues/5450)]
* agent: Fixed a bug that would cause removal of all of an agents health checks when only one service was removed. [[GH-5456](https://github.com/hashicorp/consul/issues/5456)]
* connect: Fixed a bug where `sidecar_service` registered proxies might not be removed correctly due to ACLs for the service being removed first dissallowing the agent permission to delete the proxy. [[GH-5482](https://github.com/hashicorp/consul/pull/5482)]
* Fixed a potential privilege escalation issue with the Consul 1.4.X ACL system when ACL token replication was enabled. (CVE-2019-8336) [[GH-5423](https://github.com/hashicorp/consul/issues/5423)]
* agent: Fixed a bug that could cause invalid memberlist protocol versions to propagate throughout the cluster. [[GH-3217](https://github.com/hashicorp/consul/issues/3217)]
* agent: Ensure that reaped servers are removed from RPC routing. [[GH-5317](https://github.com/hashicorp/consul/pull/5317)]
* acl: Fix potential race condition when listing or retrieving ACL tokens. [[GH-5412](https://github.com/hashicorp/consul/pull/5412)]
* agent: Fixed race condition that could turn up while registering services on the local agent. [[GH-4998](https://github.com/hashicorp/consul/issues/4998)]
* connect: Sidecar services now inherit tags and service metadata of the parent service by default. [[GH-5291](https://github.com/hashicorp/consul/pull/5291)]
* connect: Envoy proxies can now have cluster-specific config overrides via new "escape hatches": [[GH-5308](https://github.com/hashicorp/consul/pull/5308)]
* agent: Added opt-in ACL token persistence for tokens set with the agent/token/* endpoints: [[GH-5328](https://github.com/hashicorp/consul/pull/5328)]
* agent: Default to requiring protocol version 1.2 for TLS connections. The docs previously said this was going to be the default in 0.8+ but it had been left at 1.0 until now. [[GH-5340](https://github.com/hashicorp/consul/pull/5340)]
* dns: Fixed a bug that would cause node meta TXT records to always be generated even if they were not used in the responses. [[GH-5271](https://github.com/hashicorp/consul/issues/5271)]
**Note:** Consul 1.4.1 can break compatibility with older versions of the Consul Go API client. At this time, we recommend that you not upgrade to 1.4.1 if you use the Go API client or other applications that utilize it such as Nomad. Read more: [[GH-5270](https://github.com/hashicorp/consul/issues/5270)]
* api: The transaction API now supports catalog operations for interacting with nodes, services and checks. See the [transacton API page](https://www.consul.io/api/txn.html#tables-of-operations) for more information. [[GH-4869](https://github.com/hashicorp/consul/pull/4869)]
* Fixed an issue that caused `verify_server_hostname` to not implicitly configure `verify_outgoing` to true. The documentation stated this was implicit. The previous implementation had a bug that resulted in this being partially incorrect and resulted in plaintext communication in agent-to-agent RPC when `verify_outgoing` was not explicitly set. (CVE-2018-19653) [[GH-5069](https://github.com/hashicorp/consul/issues/5069)]
* agent: Improve blocking queries for services that do not exist. [[GH-4810](https://github.com/hashicorp/consul/pull/4810)]
* api: Added new `/v1/agent/health/service/name/<service name>` and `/v1/agent/health/service/id/<service id>` endpoints to allow querying a services status from the agent itself and avoid querying a Consul server. [[GH-2488](https://github.com/hashicorp/consul/issues/2488)]
* api: Added a new `allow_write_http_from` configuration to set which CIDR network ranges can send non GET/HEAD/OPTIONS HTTP requests. Requests originating from other addresses will be denied. [[GH-4712](https://github.com/hashicorp/consul/issues/4712)]
* cli: Added a new cli command: `consul tls` with subcommands `ca create` and `cert create` to help bootstrapping a secure agent TLS setup. This includes a new guide for creating certificates.
* connect: clients are smarter about when they regenerate leaf certificates to improve performance and reliability [[GH-5091](https://github.com/hashicorp/consul/pull/5091)]
* gossip: CPU performance improvements to memberlist gossip on very large clusters [[GH-5189](https://github.com/hashicorp/consul/pull/5189)]
* connect: Added support for prepared query upstream proxy destination type watching. [[GH-4969](https://github.com/hashicorp/consul/issues/4969)
* connect: (Consul Enterprise) Now forwards any intention API calls from secondary datacenters to the primary instead of erroring when intention replication is enabled.
* connect: Now controls rate of Certificate Signing Requests during a CA rotation so the servers aren't overwhelmed. [[GH-5228](https://github.com/hashicorp/consul/pull/5228)]
* acl: Fixed a concurrent policy resolution issue that would fail to resolve policies for a token [[GH-5219](https://github.com/hashicorp/consul/issues/5219)]
* acl: Fixed a few racey edge cases regarding policy resolution where the RPC request could error out due to the token used for the request being deleted or modified after the token was read but before policy resolution. [[GH-5246](https://github.com/hashicorp/consul/pull/5246)]
* acl: Fixed a bug that would cause legacy ACL tokens of type management to not get full privileges when they also had rules set on them. [[GH-5261](https://github.com/hashicorp/consul/pull/5261)]
* agent: Consul 1.2.3 added DNS weights but this caused an issue with agent Anti-Entropy that didn't set the same default and so performed a re-sync every 2 minutes despite no changes. [[GH-5096](https://github.com/hashicorp/consul/pull/5096)]
* agent: Fix an anti-entropy state syncing issue where an invalid token being used for registration of 1 service could cause a failure to register a different service with a valid token. [[GH-3676](https://github.com/hashicorp/consul/issues/3676)]
* agent: Fixed a bug where agent cache could return an error older than the last non-error value stored. This mostly affected Connect bootstrapping in integration environments but lead to some very hard to track down "impossible" issues [[GH-4480](https://github.com/hashicorp/consul/issues/4480)]
* agent: Fixed issue where DNS weights added in 1.2.3 caused unnecessary Anti-Entropy syncs due to implicit vs explicit default weights being considered "different". [[GH-5126](https://github.com/hashicorp/consul/pull/5126)]
* api: Fixed an issue where service discovery requests that use both `?cached` and multiple repeated tag filters might incorrectly see the cached result for a different query [[GH-4987](https://github.com/hashicorp/consul/pull/4987)]
* api: Fixed an issue causing blocking query wait times to not be used when retrieving leaf certificates. [[GH-4462](https://github.com/hashicorp/consul/issues/4462)]
* connect: Fixed an issue where a blank CA config could be written to a snapshot when Connect was disabled. [[GH-4954](https://github.com/hashicorp/consul/pull/4954)]
* connect: Fixed a bug with the create and modify indices of leaf certificates not being incremented properly. [[GH-4463](https://github.com/hashicorp/consul/issues/4463)]
* debug: Fixed an issue causing the debug archive to not be gzipped. [[GH-5141](https://github.com/hashicorp/consul/issues/5141)]
* dns: Fix an issue causing infinite recursion for some DNS queries when a nodes address had bee misconfigured [[GH-4907](https://github.com/hashicorp/consul/issues/4907)]
* watch: Fix a data race during setting up a watch plan. [[GH-4357](https://github.com/hashicorp/consul/issues/4357)]
* ui: Correctly encode/decode URLs within the KV areas. Also encode/decode slashes in URLS related to service names [[GH5206](https://github.com/hashicorp/consul/pull/5206)]
* snapshot: Fixed a bug where node ID and datacenter weren't being included in or restored from the snapshots. [[GH-4872](https://github.com/hashicorp/consul/issues/4872)]
* api: Fixed migration issue where changes to allow multiple tags in 1.3.0 would cause broken results during a migration from earlier versions [[GH-4944](https://github.com/hashicorp/consul/pull/4944)]
* api: Service discovery endpoints now support [caching results in the local agent](https://www.consul.io/api/index.html#agent-caching). [[GH-4541](https://github.com/hashicorp/consul/pull/4541)]
* ui: Improve layout of node 'cards' by restricting the grid layout to a maximum of 4 columns [[GH-4761]](https://github.com/hashicorp/consul/pull/4761)
* ui: Load the TextEncoder/Decoder polyfill dynamically so it's not downloaded to browsers with native support [[GH-4767](https://github.com/hashicorp/consul/pull/4767)]
* api: /health and /catalog endpoints now support filtering by multiple tags [[GH-1781](https://github.com/hashicorp/consul/issues/1781)]
* agent: Only update service `ModifyIndex` when it's state actually changes. This makes service watches much more efficient on large clusters. [[GH-4720](https://github.com/hashicorp/consul/pull/4720)]
* agent: (Consul Enterprise) Fixed an issue where the `non_voting_server` setting could be ignored when bootstrapping the cluster. [[GH-4699](https://github.com/hashicorp/consul/pull/4699)]
* connect: Fix to ensure leaf certificates for a service are not shared between clients on the same agent using different ACL tokens [[GH-4736](https://github.com/hashicorp/consul/pull/4736)]
* http: Added support for "Authorization: Bearer" head in addition to the X-Consul-Token header. [[GH-4483](https://github.com/hashicorp/consul/issues/4483)]
* dns: Added a way to specify SRV weights for each service instance to allow weighted DNS load-balancing. [[GH-4198](https://github.com/hashicorp/consul/pull/4198)]
* dns: Include EDNS-ECS options in EDNS responses where appropriate: see [RFC 7871](https://tools.ietf.org/html/rfc7871#section-7.1.3) [[GH-4647](https://github.com/hashicorp/consul/pull/4647)]
* connect: TLS certificate readiness now performs x509 certificate verification to determine whether the cert is usable. [[GH-4540](https://github.com/hashicorp/consul/pull/4540)]
* gossip: Improvements to Serf and memberlist improving gossip stability on very large clusters (over 35k tested) [[GH-4511](https://github.com/hashicorp/consul/pull/4511)]
* agent: Fixed a panic when serf_wan port was -1 but a reconnect_timeout_wan value was set. [[GH-4515](https://github.com/hashicorp/consul/issues/4515)]
* agent: Start with invalid http configuration again, even though the build-in proxy for connect won't start in that case. [[GH-4655](https://github.com/hashicorp/consul/pull/4655)]
* dns: Fixes a bug with the DNS recursor, where we would not move onto the next provided recursor if we encounter a **SERVFAIL** or **REFUSED** status. [[GH-4461](https://github.com/hashicorp/consul/pull/4461)]
* server: Fixed an issue where autopilot health checking could mistakenly mark healthy servers as failed, causing a non-voting server to be promoted unnecessarily. [[GH-4528]](https://github.com/hashicorp/consul/pull/4528)
* snapshot: Fixed a bug where node metadata wasn't being included in or restored from the snapshots. [[GH-4524](https://github.com/hashicorp/consul/issues/4524)]
* connect: Fixed a bug where managed proxy instances registered for instances with different name and ID and with restrictive ACL would not be allowed. [[GH-4619](https://github.com/hashicorp/consul/issues/4619)]
* connect: Fixed a bug where Checks with `deregister_critical_service_after` would deregister the service but not remove the managed proxy [[GH-4649](github.com/hashicorp/consul/pull/4649)]
* connect: Fixed a bug that would output an error about pruning CAs every hour on the leader and might cause some CA configurations not to be pruned correctly [[GH-4669](https://github.com/hashicorp/consul/pull/4669)]
* ui: Improve layout on screens of a large portrait orientation [[GH-4564]](https://github.com/hashicorp/consul/pull/4564)
* ui: Various browser layout bugs for various vendors/setups [[GH-4608]](https://github.com/hashicorp/consul/pull/4608) [[GH-4613]](https://github.com/hashicorp/consul/pull/4613) [[GH-4615]](https://github.com/hashicorp/consul/pull/4615)
* acl: Fixed an issue where writes operations on the Keyring and Operator were being allowed with a default allow policy even when explicitly denied in the policy. [[GH-4378](https://github.com/hashicorp/consul/issues/4378)]
* **Alias Checks:** Alias checks allow a service or node to alias the health status of another service or node in the cluster. [[PR-4320](https://github.com/hashicorp/consul/pull/4320)]
* cli: Added `-serf-wan-port`, `-serf-lan-port`, and `-server-port` flags to CLI for cases where these can't be specified in config files and `-hcl` is too cumbersome. [[GH-4353](https://github.com/hashicorp/consul/pull/4353#issuecomment-404408827)]
* proxy: With `-register` flag, heartbeat failures will only log once service registration succeeds. [[GH-4314](https://github.com/hashicorp/consul/pull/4314)]
* http: 1.0.3 introduced rejection of non-printable chars in HTTP URLs due to a security vulnerability. Some users who had keys written with an older version which are now dissallowed were unable to delete them. A new config option [disable_http_unprintable_char_filter](https://www.consul.io/docs/agent/options.html#disable_http_unprintable_char_filter) is added to allow those users to remove the offending keys. Leaving this new option set long term is strongly discouraged as it bypasses filtering necessary to prevent some known vulnerabilities. [[GH-4442](https://github.com/hashicorp/consul/pull/4442)]
* agent: Make some Gossip tuneables configurable via the config file [[GH-4444](https://github.com/hashicorp/consul/pull/4444)]
* ui: Included searching on `.Tags` when using the freetext search field. [[GH-4383](https://github.com/hashicorp/consul/pull/4383)]
* ui: Service.ID's are now shown in the Service detail page and (only if it is different from the service name) the Node Detail > [Services] tab. [[GH-4387](https://github.com/hashicorp/consul/pull/4387)]
* acl/connect: Fix an issue that was causing managed proxies not to work when ACLs were enabled. [[GH-4441](https://github.com/hashicorp/consul/issues/4441)]
* connect: Fix issue with managed proxies and watches attempting to use a client addr that is 0.0.0.0 or :: [[GH-4403](https://github.com/hashicorp/consul/pull/4403)]
* connect: Allow Native and Unmanaged proxy configurations via config file [[GH-4443](https://github.com/hashicorp/consul/pull/4443)]
* connect: Fix bug causing 100% CPU on agent when Connect is disabled but a proxy is still running [[GH-4421](https://github.com/hashicorp/consul/issues/4421)]
* proxy: Don't restart proxies setup in a config file when Consul restarts [[GH-4407](https://github.com/hashicorp/consul/pull/4407)]
* ui: Display the Service.IP address instead of the Node.IP address in the Service detail view. [[GH-4410](https://github.com/hashicorp/consul/pull/4410)]
* ui: Watch for trailing slash stripping 301 redirects and forward the user to the correct location. [[GH-4373](https://github.com/hashicorp/consul/pull/4373)]
* connect: Fixed an issue in the connect native HTTP client where it failed to resolve service names. [[GH-4392](https://github.com/hashicorp/consul/pull/4392)]
* acl: Add async-cache down policy mode to always do ACL token refreshes in the background to reduce latency. [[GH-3524](https://github.com/hashicorp/consul/issues/3524)]
* proxy: Pass through HTTP client env vars to managed proxies so that they can connect back to Consul over HTTPs when not serving HTTP. [[PR-4374](https://github.com/hashicorp/consul/pull/4374)]
* agent: Service registration with "services" does not error on Connect upstream configuration. [[GH-4308](https://github.com/hashicorp/consul/issues/4308)]
* dns: Ensure that only 1 CNAME is returned when querying for services that have non-IP service addresses. [[PR-4328](https://github.com/hashicorp/consul/pull/4328)]
* api: Fixed issue where `Lock` and `Semaphore` would return earlier than their requested timeout when unable to acquire the lock. [[GH-4003](https://github.com/hashicorp/consul/issues/4003)], [[GH-3262](https://github.com/hashicorp/consul/issues/3262)], [[GH-2399](https://github.com/hashicorp/consul/issues/2399)]
* **Connect Feature Beta**: This version includes a major new feature for Consul named Connect. Connect enables secure service-to-service communication with automatic TLS encryption and identity-based authorization. For more details and links to demos and getting started guides, see the [announcement blog post](https://www.hashicorp.com/blog/consul-1-2-service-mesh).
* agent: A Consul user-agent string is now sent to providers when making retry-join requests [[GH-4013](https://github.com/hashicorp/consul/issues/4013)]
* agent: Add configuration entry to control including TXT records for node meta in DNS responses [PR-4215](https://github.com/hashicorp/consul/pull/4215)
* api: Added support for Prometheus client format in metrics endpoint with `?format=prometheus` (see [docs](https://www.consul.io/api/agent.html#view-metrics)) [[GH-4014](https://github.com/hashicorp/consul/issues/4014)]
-`CheckID` has been removed from config file check definitions (use `id` instead).
-`script` has been removed from config file check definitions (use `args` instead).
-`enableTagOverride` is no longer valid in service definitions (use `enable_tag_override` instead).
- The [deprecated set of metric names](https://consul.io/docs/upgrade-specific.html#metric-names-updated) (beginning with `consul.consul.`) has been removed along with the `enable_deprecated_names` option from the metrics configuration.
* agent: `start_join`, `start_join_wan`, `retry_join`, `retry_join_wan` config params now all support go-sockaddr templates [[GH-4102](https://github.com/hashicorp/consul/pull/4102)]
* server: Added new configuration options `raft_snapshot_interval` and `raft_snapshot_threshold` to allow operators to configure how often servers take raft snapshots. The default values for these have been tuned for large and busy clusters with high write load. [[GH-4105](https://github.com/hashicorp/consul/pull/4105/)]
* agent: Updated serf library for two bug fixes - allow enough time for leave intents to propagate [[GH-510](https://github.com/hashicorp/serf/pull/510)] and preventing a deadlock [[GH-507](https://github.com/hashicorp/serf/pull/510)]
* agent: When node-level checks (e.g. maintenance mode) were deleted, some watchers currently in between blocking calls may have missed the change in index. See [[GH-3970](https://github.com/hashicorp/consul/pull/3970)]
* agent: Blocking queries on service-specific health and catalog endpoints now return a per-service `X-Consul-Index` improving watch performance on very busy clusters. [[GH-3890](https://github.com/hashicorp/consul/issues/3890)]. **Note this may break blocking clients that relied on undocumented implementation details** as noted in the [upgrade docs](https://github.com/hashicorp/consul/blob/master/website/source/docs/upgrading.html.md#upgrade-from-version-106-to-higher).
* agent: Added a new `discover-max-stale` config option to enable stale requests for service discovery endpoints. [[GH-4004](https://github.com/hashicorp/consul/issues/4004)]
* agent: Fixed an issue where the coordinate update endpoint was not correctly parsing the ACL token. [[GH-3892](https://github.com/hashicorp/consul/issues/3892)]
* agent: Fixed an issue where `consul monitor` couldn't be terminated until the first log line is delivered [[GH-3891](https://github.com/hashicorp/consul/issues/3891)]
* agent: Added warnings for when a node name isn't a valid DNS name and when the node name, a service name or service tags would exceed the allowed lengths for DNS names [[GH-3854](https://github.com/hashicorp/consul/issues/3854)]
* agent: Added truncation of TCP DNS responses to prevent errors for exceeding message size limits [[GH-3850](https://github.com/hashicorp/consul/issues/3850)]
* agent: Added -config-format flag to validate command to specify the syntax that should be used for parsing the config [[GH-3996](https://github.com/hashicorp/consul/issues/3996)]
* server: Fixed an issue where the leader could miss clean up after a leadership transition. [[GH-3909](https://github.com/hashicorp/consul/issues/3909)]
We found [[GH-3867](https://github.com/hashicorp/consul/issues/3867)] after cutting the 1.0.4 release and pushing the 1.0.4 release tag, so we decided to scuttle that release and push 1.0.5 instead with a fix for that issue.
* dns: Updated DNS vendor library to pick up bug fix in the DNS server where an open idle connection blocks the accept loop. [[GH-3859](https://github.com/hashicorp/consul/issues/3859)]
* agent: Added support for gRPC health checks that probe the standard gRPC health endpoint. [[GH-3073](https://github.com/hashicorp/consul/issues/3073)]
* agent: Fixed an issue where health checks added to services with tags would cause extra periodic writes to the Consul servers, even if nothing had changed. This could cause extra churn on downstream applications like consul-template or Fabio. [[GH-3845](https://github.com/hashicorp/consul/issues/3845)]
* agent: Fixed several areas where reading from catalog, health, or agent HTTP endpoints could make unintended mofidications to Consul's state in a way that would cause unnecessary anti-entropy syncs back to the Consul servers. This could cause extra churn on downstream applications like consul-template or Fabio. [[GH-3867](https://github.com/hashicorp/consul/issues/3867)]
* agent: Fixed an issue where Serf events for failed Consul servers weren't being proactively processed by the RPC router. This would prvent Consul from proactively choosing a new server, and would instead wait for a failed RPC request before choosing a new server. This exposed clients to a failed request, when often the proactive switching would avoid that. [[GH-3864](https://github.com/hashicorp/consul/issues/3864)]
* agent: Updated Consul's HTTP server to ban all URLs containing non-printable characters (a bad request status will be returned for these cases). This affects some user-facing areas like key/value entry key names which are carried in URLs. [[GH-3762](https://github.com/hashicorp/consul/issues/3762)]
* agent: Added agent-side telemetry around Catalog APIs to provide insight on Consul's operation from the user's perspecive. [[GH-3765](https://github.com/hashicorp/consul/issues/3765)]
* api: Added missing `CheckID` and `Name` fields to API client's `AgentServiceCheck` structure so that IDs and names can be set when registering checks with services. [[GH-3788](https://github.com/hashicorp/consul/issues/3788)]
* agent: Ignore malformed leftover service/check files and warn about them instead of refusing to start. [[GH-1221](https://github.com/hashicorp/consul/issues/1221)]
* agent: Stopped looging messages about zero RTTs when updating network coordinates since they are not harmful to the algorithm. Since we are still trying to find the root cause of these zero measurements, we added new metrics counters so these are still observable. [[GH-3789](https://github.com/hashicorp/consul/issues/3789)]
* server: (Consul Enterprise) Fixed an issue where unhealthy servers were not replaced in a redundancy zone by autopilot (servers previously needed to be removed in order for a replacement to occur).
* ui: Added a URI escape around key/value keys so that it's not possible to create unexpected partial key names when entering characters like `?` inside a key. [[GH-3760](https://github.com/hashicorp/consul/issues/3760)]
* agent: Updated Serf to activate a new feature that resizes its internal message broadcast queue size based on the cluster size. This helps control the amount of memory used by the agent, but prevents spurious warnings about dropped messages in very large Consul clusters. The intent queue warnings have also been disabled since queue telemetry was already available and a simple fixed limit isn't applicable to all clusters, so it could cause a high rate of warnings about intent queue depth that were not useful or indicative of an actual issue. [[GH-3705](https://github.com/hashicorp/consul/issues/3705)]
* agent: Updates posener/complete library to 1.0, which allows autocomplete for flags after an equal sign, and simplifies autocomplete functions. [[GH-3646](https://github.com/hashicorp/consul/issues/3646)]
* agent: Updated memberlist to pull in a fix for negative RTT measurements and their associated log messages about rejected coordinates. [[GH-3704](https://github.com/hashicorp/consul/issues/3704)]
* agent: Fixed an issue where node metadata specified via command line arguments overrode node metadata specified by configuration files, instead of merging as was done in versions of Consul prior to 1.0. [[GH-3716](https://github.com/hashicorp/consul/issues/3716)]
* agent: Fixed an issue with the /v1/session/create API where it wasn't possible to create a session without the `serfHealth` check. This is now possible again by including the `checks` key in the JSON body with an empty list. [[GH-3732](https://github.com/hashicorp/consul/issues/3732)]
* agent: Fixed an issue with anti-entropy syncing where checks for services with tags would cause periodic updates to the catalog, even when nothing had changed, causing the Raft index to grow slowly (~2 minutes per node per check) over time, and causing unnecessary writes and wake ups for blocking queries. [[GH-3642](https://github.com/hashicorp/consul/issues/3642)], [[GH-3259](https://github.com/hashicorp/consul/issues/3259)]
* server: Fixed an issue with KV store tombstone tracking where bin tracking was being confused by monotonic time information carried in time stamps, resulting in many unnecessary bins. [[GH-3670](https://github.com/hashicorp/consul/issues/3670)]
* server: Fixed an issue where it wasn't possible to disable Autopilot's dead server cleanup behavior using configuration files. [[GH-3730](https://github.com/hashicorp/consul/issues/3730)]
* server: Removed the 60 second timeout when restoring snapshots, which could cause large restores to fail on slower servers. [[GH-3326](https://github.com/hashicorp/consul/issues/3326)]
* **New Auto Join Cloud Providers:** Retry join support was added for Aliyun (Alibaba Cloud), Digital Ocean, OpenStack, and Scaleway. Instance metadata can be used with these to make it easy to form Consul clusters. [[GH-3634](https://github.com/hashicorp/consul/issues/3634)]
* **HTTP/2 Support:** If TLS is enabled on a Consul agent it will automatically negotiate to use HTTP/2 for suitably configured clients accessing the client API. This allows clients to multiplex requests over the same TCP connection, such as multiple, simultaneous blocking queries. [[GH-3657](https://github.com/hashicorp/consul/issues/3657)]
* agent: (Consul Enterprise) Added [AWS KMS support](http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingKMSEncryption.html) for S3 snapshots using the snapshot agent.
* agent: Watches in the Consul agent can now be configured to invoke an HTTP endpoint instead of an executable. [[GH-3305](https://github.com/hashicorp/consul/issues/3305)]
* agent: Added a new [`-config-format`](https://www.consul.io/docs/agent/options.html#_config_format) command line option which can be set to `hcl` or `json` to specify the format of configuration files. This is useful for cases where the file name cannot be controlled in order to provide the required extension. [[GH-3620](https://github.com/hashicorp/consul/issues/3620)]
* agent: DNS recursors can now be specified as [go-sockaddr](https://godoc.org/github.com/hashicorp/go-sockaddr/template) templates. [[GH-2932](https://github.com/hashicorp/consul/issues/2932)]
* agent: Serf snapshots no longer save network coordinate information. This enables recovery from errors upon agent restart. [[GH-489](https://github.com/hashicorp/serf/issues/489)]
* agent: Added defensive code to prevent out of range ping times from infecting network coordinates. Updates to the coordinate system with negative round trip times or round trip times higher than 10 seconds will log an error but will be ignored.
* agent: The agent now warns when there are extra unparsed command line arguments and refuses to start. [[GH-3397](https://github.com/hashicorp/consul/issues/3397)]
* agent: Updated go-sockaddr library to get CoreOS route detection fixes and the new `mask` functionality. [[GH-3633](https://github.com/hashicorp/consul/issues/3633)]
* agent: Added a new [`enable_agent_tls_for_checks`](https://www.consul.io/docs/agent/options.html#enable_agent_tls_for_checks) configuration option that allows HTTP health checks for services requiring 2-way TLS to be checked using the agent's credentials. [[GH-3364](https://github.com/hashicorp/consul/issues/3364)]
* agent: Made logging of health check status more uniform and moved log entries with full check output from DEBUG to TRACE level for less noise. [[GH-3683](https://github.com/hashicorp/consul/issues/3683)]
* agent: Consul 1.0 shipped with an issue where `Args` was erroneously named `ScriptArgs` for health check definitions in the /v1/agent/check/register and /v1/agent/service/register APIs. Added code to accept `Args` so that the JSON format matches that of health checks in configuration files. The `ScriptArgs` form will still be supported for backwards compatibility. [[GH-3587](https://github.com/hashicorp/consul/issues/3587)]
* agent: Docker container checks running on Linux could get into a flapping state because the Docker agent seems to close the connection prematurely even though the body is transferred. This caused a "connection reset by peer" error which put the check into `critical` state. As of Consul 1.0.1 the "connection reset by peer" error is ignored for the `/exec/<execID>/start` command of the Docker API. [[GH-3576](https://github.com/hashicorp/consul/issues/3576)]
* agent: Added new form of `consul.http.*` metrics that were accidentally left out of Consul 1.0. [[GH-3654](https://github.com/hashicorp/consul/issues/3654)]
* agent: Fixed an issue with the server manager where periodic server client connection rebalancing could select a failed server. This affects agents in client mode, as well as servers talking to other servers, including over the WAN. [[GH-3463](https://github.com/hashicorp/consul/issues/3463)]
* agent: IPv6 addresses without port numbers and without surrounding brackets are now properly handled for joins. This affects all join types, but in particular this was discovered with AWS joins where the APIs return addresses formatted this way. [[GH-3671](https://github.com/hashicorp/consul/issues/3671)]
* agent: Fixed a rare startup panic of the Consul agent related to the LAN Serf instance ordering with the router manager. [[GH-3680](https://github.com/hashicorp/consul/issues/3680)]
* agent: Added back an exception for the `snapshot_agent` config key so that those configs can again live alongside Consul's configs. [[GH-3678](https://github.com/hashicorp/consul/issues/3678)]
* dns: Fixed an issue were components of a host name near the datacenter could be quietly ignored (eg. `foo.service.dc1.extra.consul` would silently ignore `.extra`); now an `NXDOMAIN` error will be returned. [[GH-3200](https://github.com/hashicorp/consul/issues/3200)]
* server: Fixed an issue where performing rolling updates of Consul servers could result in an outage from old servers remaining in the cluster. Consul's Autopilot would normally remove old servers when new ones come online, but it was also waiting to promote servers to voters in pairs to maintain an odd quorum size. The pairwise promotion feature was removed so that servers become voters as soon as they are stable, allowing Autopilot to remove old servers in a safer way. When upgrading from Consul 1.0, you may need to manually force-leave old servers as part of a rolling update to Consul 1.0.1. [[GH-3611](https://github.com/hashicorp/consul/issues/3611)]
* server: Fixed a deadlock where tombstone garbage collection for the KV store could block other KV operations, stalling writes on the leader. [[GH-3700](https://github.com/hashicorp/consul/issues/3700)]
* ui: Fixed an XSS issue with Consul's built-in web UI where node names were not being properly escaped. [[GH-3578](https://github.com/hashicorp/consul/issues/3578)]
* **Raft Protocol Now Defaults to 3:** The [`-raft-protocol`](https://www.consul.io/docs/agent/options.html#_raft_protocol) default has been changed from 2 to 3, enabling all [Autopilot](https://www.consul.io/docs/guides/autopilot.html) features by default. Version 3 requires Consul running 0.8.0 or newer on all servers in order to work, so if you are upgrading with older servers in a cluster then you will need to set this back to 2 in order to upgrade. See [Raft Protocol Version Compatibility](https://www.consul.io/docs/upgrade-specific.html#raft-protocol-version-compatibility) for more details. Also the format of `peers.json` used for outage recovery is different when running with the lastest Raft protocol. See [Manual Recovery Using peers.json](https://www.consul.io/docs/guides/outage.html#manual-recovery-using-peers-json) for a description of the required format. [[GH-3477](https://github.com/hashicorp/consul/issues/3477)]
* **Config Files Require an Extension:** As part of supporting the [HCL](https://github.com/hashicorp/hcl#syntax) format for Consul's config files, an `.hcl` or `.json` extension is required for all config files loaded by Consul, even when using the [`-config-file`](https://www.consul.io/docs/agent/options.html#_config_file) argument to specify a file directly. [[GH-3480](https://github.com/hashicorp/consul/issues/3480)]
* **Deprecated Options Have Been Removed:** All of Consul's previously deprecated command line flags and config options have been removed, so these will need to be mapped to their equivalents before upgrading. [[GH-3480](https://github.com/hashicorp/consul/issues/3480)]
* **`statsite_prefix` Renamed to `metrics_prefix`:** Since the `statsite_prefix` configuration option applied to all telemetry providers, `statsite_prefix` was renamed to [`metrics_prefix`](https://www.consul.io/docs/agent/options.html#telemetry-metrics_prefix). Configuration files will need to be updated when upgrading to this version of Consul. [[GH-3498](https://github.com/hashicorp/consul/issues/3498)]
* **`advertise_addrs` Removed:** This configuration option was removed since it was redundant with `advertise_addr` and `advertise_addr_wan` in combination with `ports` and also wrongly stated that you could configure both host and port. [[GH-3516](https://github.com/hashicorp/consul/issues/3516)]
* **Escaping Behavior Changed for go-discover Configs:** The format for [`-retry-join`](https://www.consul.io/docs/agent/options.html#retry-join) and [`-retry-join-wan`](https://www.consul.io/docs/agent/options.html#retry-join-wan) values that use [go-discover](https://github.com/hashicorp/go-discover) Cloud auto joining has changed. Values in `key=val` sequences must no longer be URL encoded and can be provided as literals as long as they do not contain spaces, backslashes `\` or double quotes `"`. If values contain these characters then use double quotes as in `"some key"="some value"`. Special characters within a double quoted string can be escaped with a backslash `\`. [[GH-3417](https://github.com/hashicorp/consul/issues/3417)]
* **HTTP Verbs are Enforced in Many HTTP APIs:** Many endpoints in the HTTP API that previously took any HTTP verb now check for specific HTTP verbs and enforce them. This may break clients relying on the old behavior. [[GH-3405](https://github.com/hashicorp/consul/issues/3405)]
* **Unauthorized KV Requests Return 403:** When ACLs are enabled, reading a key with an unauthorized token returns a 403. This previously returned a 404 response.
* **Config Section of Agent Self Endpoint has Changed:** The /v1/agent/self endpoint's `Config` section has often been in flux as it was directly returning one of Consul's internal data structures. This configuration structure has been moved under `DebugConfig`, and is documents as for debugging use and subject to change, and a small set of elements of `Config` have been maintained and documented. See [Read Configuration](https://www.consul.io/api/agent.html#read-configuration) endpoint documentation for details. [[GH-3532](https://github.com/hashicorp/consul/issues/3532)]
* **Deprecated `configtest` Command Removed:** The `configtest` command was deprecated and has been superseded by the `validate` command.
* **Undocumented Flags in `validate` Command Removed:** The `validate` command supported the `-config-file` and `-config-dir` command line flags but did not document them. This support has been removed since the flags are not required.
* **Metric Names Updated:** Metric names no longer start with `consul.consul`. To help with transitioning dashboards and other metric consumers, the field `enable_deprecated_names` has been added to the telemetry section of the config, which will enable metrics with the old naming scheme to be sent alongside the new ones. [[GH-3535](https://github.com/hashicorp/consul/issues/3535)]
* **Checks Validated On Agent Startup:** Consul agents now validate health check definitions in their configuration and will fail at startup if any checks are invalid. In previous versions of Consul, invalid health checks would get skipped. [[GH-3559](https://github.com/hashicorp/consul/issues/3559)]
* **Support for HCL Config Files:** Consul now supports HashiCorp's [HCL](https://github.com/hashicorp/hcl#syntax) format for config files. This is easier to work with than JSON and supports comments. As part of this change, all config files will need to have either an `.hcl` or `.json` extension in order to specify their format. [[GH-3480](https://github.com/hashicorp/consul/issues/3480)]
* **Support for Binding to Multiple Addresses:** Consul now supports binding to multiple addresses for its HTTP, HTTPS, and DNS services. You can provide a space-separated list of addresses to [`-client`](https://www.consul.io/docs/agent/options.html#_client) and [`addresses`](https://www.consul.io/docs/agent/options.html#addresses) configurations, or specify a [go-sockaddr](https://godoc.org/github.com/hashicorp/go-sockaddr/template) template that resolves to multiple addresses. [[GH-3480](https://github.com/hashicorp/consul/issues/3480)]
* **Support for RFC1464 DNS TXT records:** Consul DNS responses now contain the node meta data encoded according to RFC1464 as TXT records. [[GH-3343](https://github.com/hashicorp/consul/issues/3343)]
* **Support for Running Subproccesses Directly Without a Shell:** Consul agent checks and watches now support an `args` configuration which is a list of arguments to run for the subprocess, which runs the subprocess directly without a shell. The old `script` and `handler` configurations are now deprecated (specify a shell explicitly if you require one). A `-shell=false` option is also available on `consul lock`, `consul watch`, and `consul exec` to run the subprocesses associated with those without a shell. [[GH-3509](https://github.com/hashicorp/consul/issues/3509)]
* **Sentinel Integration:** (Consul Enterprise) Consul's ACL system integrates with [Sentinel](https://www.consul.io/docs/guides/sentinel.html) to enable code policies that apply to KV writes.
* agent: Added support to detect public IPv4 and IPv6 addresses on AWS. [[GH-3471](https://github.com/hashicorp/consul/issues/3471)]
* agent: Improved /v1/operator/raft/configuration endpoint which allows Consul to avoid an extra agent RPC call for the `consul operator raft list-peers` command. [[GH-3449](https://github.com/hashicorp/consul/issues/3449)]
* agent: Improved ACL system for the KV store to support list permissions. This behavior can be opted in. For more information, see the [ACL Guide](https://www.consul.io/docs/guides/acl.html#list-policy-for-keys). [[GH-3511](https://github.com/hashicorp/consul/issues/3511)]
* agent: Updates miekg/dns library to later version to pick up bug fixes and improvements. [[GH-3547](https://github.com/hashicorp/consul/issues/3547)]
* agent: Added automatic retries to the RPC path, and a brief RPC drain time when servers leave. These changes make Consul more robust during graceful leaves of Consul servers, such as during upgrades, and help shield applications from "no leader" errors. These are configured with new [`performance`](https://www.consul.io/docs/agent/options.html#performance) options. [[GH-3514](https://github.com/hashicorp/consul/issues/3514)]
* agent: Added a new `discard_check_output` agent-level configuration option that can be used to trade off write load to the Consul servers vs. visibility of health check output. This is reloadable so it can be toggled without fully restarting the agent. [[GH-3562](https://github.com/hashicorp/consul/issues/3562)]
* api: Updated the API client to ride out network errors when monitoring locks and semaphores. [[GH-3553](https://github.com/hashicorp/consul/issues/3553)]
* cli: `consul lock` and `consul watch` commands will forward `TERM` and `KILL` signals to their child subprocess. [[GH-3509](https://github.com/hashicorp/consul/issues/3509)]
* cli: Added support for [autocompletion](https://www.consul.io/docs/commands/index.html#autocompletion). [[GH-3412](https://github.com/hashicorp/consul/issues/3412)]
* server: Updated BoltDB to final version 1.3.1. [[GH-3502](https://github.com/hashicorp/consul/issues/3502)]
* server: Improved dead member reap algorithm to fix edge cases where servers could get left behind. [[GH-3452](https://github.com/hashicorp/consul/issues/3452)]
* agent: Fixed an issue where disabling both the http and https interfaces would cause a watch-related error on agent startup, even when no watches were defined. [[GH-3425](https://github.com/hashicorp/consul/issues/3425)]
* agent: Added an additional step to kill health check scripts that timeout on all platforms except Windows, and added a wait so that it's not possible to run multiple instances of the same health check script at the same time. [[GH-3565](https://github.com/hashicorp/consul/issues/3565)]
* cli: If the `consul operator raft list-peers` command encounters an error it will now exit with a non-zero exit code. [[GH-3513](https://github.com/hashicorp/consul/issues/3513)]
* server: Fixed an issue where the leader server could get into a state where it was no longer performing the periodic leader loop duties and unable to serve consistent reads after a barrier timeout error. [[GH-3545](https://github.com/hashicorp/consul/issues/3545)]
* **LAN Network Segments:** (Consul Enterprise) Added a new [Network Segments](https://www.consul.io/docs/guides/segments.html) capability which allows users to configure Consul to support segmented LAN topologies with multiple, distinct gossip pools. [[GH-3431](https://github.com/hashicorp/consul/issues/3431)]
* **WAN Join for Cloud Providers:** Added WAN support for retry join for Cloud providers via go-discover, including Amazon AWS, Microsoft Azure, Google Cloud, and SoftLayer. This uses the same "provider" syntax supported for `-retry-join` via the `-retry-join-wan` configuration. [[GH-3406](https://github.com/hashicorp/consul/issues/3406)]
* **RPC Rate Limiter:** Consul agents in client mode have a new [`limits`](https://www.consul.io/docs/agent/options.html#limits) configuration that enables a rate limit on RPC calls the agent makes to Consul servers. [[GH-3140](https://github.com/hashicorp/consul/issues/3140)]
* agent: Switched to using a read lock for the agent's RPC dispatcher, which prevents RPC calls from getting serialized. [[GH-3376](https://github.com/hashicorp/consul/issues/3376)]
* agent: When joining a cluster, Consul now skips the unique node ID constraint for Consul members running Consul older than 0.8.5. This makes it easier to upgrade to newer versions of Consul in an existing cluster with non-unique node IDs. [[GH-3070](https://github.com/hashicorp/consul/issues/3070)]
* build: Upgraded Go version to 1.9. [[GH-3428](https://github.com/hashicorp/consul/issues/3428)]
* server: Consul servers can re-establish quorum after all of them change their IP addresses upon a restart. [[GH-1580](https://github.com/hashicorp/consul/issues/1580)]
* ui: Changed text area font family to monospace to make it easier to manage complex text blocks. [[GH-3521](https://github.com/hashicorp/consul/issues/3521)]
* agent: Fixed an issue with consul watches not triggering when ACLs are enabled. [[GH-3392](https://github.com/hashicorp/consul/issues/3392)]
* agent: Updated memberlist library for a deadlock fix. [[GH-3396](https://github.com/hashicorp/consul/issues/3396)]
* agent: Fixed a panic when retrieving NS or SOA records on Consul clients (non-servers). This also changed the Consul server list to come from the catalog and not the agent's local state when serving these requests, so the results are consistent across a cluster. [[GH-3407](https://github.com/hashicorp/consul/issues/3407)]
* cli: Updated the CLI library to pull in a fix that prevents all subcommands from being shown when showing the agent's usage list; now just top-level commands are shown. [[GH-3448](https://github.com/hashicorp/consul/issues/3448)]
* server: Fixed an issue with Consul snapshots not saving on Windows because of errors with the `fsync` syscall. [[GH-3409](https://github.com/hashicorp/consul/issues/3409)]
* agent: Fixed an issue where the old `-retry-join-{ec2,azure,gce}` command line flags were not being honored. [[GH-3384](https://github.com/hashicorp/consul/issues/3384)]
* server: Reverted the change that made unauthorized KV queries return 403 instead of 404 because it had a minor bug that affected the operation of Vault, and in addition to fixing the bug, we identified an additional case that needed to be covered. This restores the <= 0.9.0 behavior until we can get a complete fix. [[GH-2637](https://github.com/hashicorp/consul/issues/2637)]
* **Secure ACL Token Introduction:** It's now possible to manage Consul's ACL tokens without having to place any tokens inside configuration files. This supports introduction of tokens as well as rotating. This is enabled with two new APIs:
* A new [`/v1/agent/token`](https://www.consul.io/api/agent.html#update-acl-tokens) API allows an agent's ACL tokens to be introduced without placing them into config files, and to update them without restarting the agent. See the [ACL Guide](https://www.consul.io/docs/guides/acl.html#create-an-agent-token) for an example. This was extended to ACL replication as well, along with a new [`enable_acl_replication`](https://www.consul.io/docs/agent/options.html#enable_acl_replication) config option. [GH-3324,GH-3357]
* A new [`/v1/acl/bootstrap`](https://www.consul.io/api/acl.html#bootstrap-acls) allows a cluster's first management token to be created without using the `acl_master_token` configuration. See the [ACL Guide](https://www.consul.io/docs/guides/acl.html#bootstrapping-acls) for an example. [[GH-3349](https://github.com/hashicorp/consul/issues/3349)]
* **Metrics Viewing Endpoint:** A new [`/v1/agent/metrics`](https://www.consul.io/api/agent.html#view-metrics) API displays the current values of internally tracked metrics. [[GH-3369](https://github.com/hashicorp/consul/issues/3369)]
* agent: Retry Join for Amazon AWS, Microsoft Azure, Google Cloud, and (new) SoftLayer is now handled through the https://github.com/hashicorp/go-discover library. With this all `-retry-join-{ec2,azure,gce}-*` parameters have been deprecated in favor of a unified configuration. See [`-retry-join`](https://www.consul.io/docs/agent/options.html#_retry_join) for details. [GH-3282,GH-3351]
* agent: Reports a more detailed error message if the LAN or WAN Serf instance fails to bind to an address. [[GH-3312](https://github.com/hashicorp/consul/issues/3312)]
* agent: Added NS records and corrected SOA records to allow Consul's DNS interface to work properly with zone delegation. [[GH-1301](https://github.com/hashicorp/consul/issues/1301)]
* agent: Added support for sending metrics with labels/tags to supported backends. [[GH-3369](https://github.com/hashicorp/consul/issues/3369)]
* agent: Added a new `prefix_filter` option in the `telemetry` config to allow fine-grained allowing/blocking the sending of certain metrics by prefix. [[GH-3369](https://github.com/hashicorp/consul/issues/3369)]
* cli: Added a `-child-exit-code` option to `consul lock` so that it propagates an error code of 2 if the child process exits with an error. [[GH-947](https://github.com/hashicorp/consul/issues/947)]
* docs: Added a new [Geo Failover Guide](https://www.consul.io/docs/guides/geo-failover.html) showing how to use prepared queries to implement geo failover policies for services. [[GH-3328](https://github.com/hashicorp/consul/issues/3328)]
* docs: Added a new [Consul with Containers Guide](https://www.consul.io/docs/guides/consul-containers.html) showing critical aspects of operating a Consul cluster that's run inside containers. [[GH-3347](https://github.com/hashicorp/consul/issues/3347)]
* server: Added a `RemoveEmptyTags` option to prepared query templates which will strip out any empty strings in the tags list before executing a query. This is useful when interpolating into tags in a way where the tag is optional, and where searching for an empty tag would yield no results from the query. [[GH-2151](https://github.com/hashicorp/consul/issues/2151)]
* server: Implemented a much faster recursive delete algorithm for the KV store. It has been benchmarked to be up to 100X faster on recursive deletes that affect millions of keys. [GH-1278, GH-3313]
* agent: Clean up temporary files during disk write errors when persisting services and checks. [[GH-3207](https://github.com/hashicorp/consul/issues/3207)]
* agent: Fixed an issue where DNS and client bind address templates were not being parsed via the go-sockaddr library. [[GH-3322](https://github.com/hashicorp/consul/issues/3322)]
* agent: Fixed status code on all KV store operations that fail due to an ACL issue. They now return a 403 status code, rather than a 404. [[GH-2637](https://github.com/hashicorp/consul/issues/2637)]
* agent: Fixed quoting issues in script health check on Windows. [[GH-1875](https://github.com/hashicorp/consul/issues/1875)]
* agent: Fixed an issue where `consul monitor` would exit on any empty log line. [[GH-3253](https://github.com/hashicorp/consul/issues/3253)]
* server: Updated raft library to fix issue with machine crashes causing snapshot files to not get saved to disk [[GH-3362](https://github.com/hashicorp/consul/issues/3362)]
* agent: Added a new [`enable_script_checks`](https://www.consul.io/docs/agent/options.html#_enable_script_checks) configuration option that defaults to `false`, meaning that in order to allow an agent to run health checks that execute scripts, this will need to be configured and set to `true`. This provides a safer out-of-the-box configuration for Consul where operators must opt-in to allow script-based health checks. [[GH-3087](https://github.com/hashicorp/consul/issues/3087)]
* api: Reworked `context` support in the API client to more closely match the Go standard library, and added context support to write requests in addition to read requests. [GH-3273, GH-2992]
* ui: Since the UI is now bundled with the application we no longer provide a separate UI package for downloading. [[GH-3292](https://github.com/hashicorp/consul/issues/3292)]
* agent: Added a new [`block_endpoints`](https://www.consul.io/docs/agent/options.html#block_endpoints) configuration option that allows blocking HTTP API endpoints by prefix. This allows operators to completely disallow access to specific endpoints on a given agent. [[GH-3252](https://github.com/hashicorp/consul/issues/3252)]
* cli: Added a new [`consul catalog`](https://www.consul.io/docs/commands/catalog.html) command for reading datacenters, nodes, and services from the catalog. [[GH-3204](https://github.com/hashicorp/consul/issues/3204)]
* server: (Consul Enterprise) Added a new [`consul operator area update`](https://www.consul.io/docs/commands/operator/area.html#update) command and corresponding HTTP endpoint to allow for transitioning the TLS setting of network areas at runtime. [[GH-3075](https://github.com/hashicorp/consul/issues/3075)]
* server: (Consul Enterprise) Added a new `UpgradeVersionTag` field to the Autopilot config to allow for using the migration feature to roll out configuration or cluster changes, without having to upgrade Consul itself.
* agent: Removed registration of the `consul` service from the agent since it's already handled by the leader. This means that Consul servers no longer need to have an `acl_agent_token` with write access to the `consul` service if ACLs are enabled. [[GH-3248](https://github.com/hashicorp/consul/issues/3248)]
* agent: Changed /v1/acl/clone response to 403 (from 404) when trying to clone an ACL that doesn't exist. [[GH-1113](https://github.com/hashicorp/consul/issues/1113)]
* agent: Changed the `consul exec` ACL resolution logic to use the `acl_agent_token` if it's available. This lets operators configure an `acl_agent_token` with the required `write` privilieges to the `_rexec` prefix of the KV store without giving this to the `acl_token`, which would expose those privileges to users as well. [[GH-3160](https://github.com/hashicorp/consul/issues/3160)]
* agent: Updated memberlist to get latest LAN gossip tuning based on the [Lifeguard paper published by Hashicorp Research](https://www.hashicorp.com/blog/making-gossip-more-robust-with-lifeguard/). [[GH-3287](https://github.com/hashicorp/consul/issues/3287)]
* api: Added the ability to pass in a `context` as part of the `QueryOptions` during a request. This provides a way to cancel outstanding blocking queries. [[GH-3195](https://github.com/hashicorp/consul/issues/3195)]
* api: Changed signature for "done" channels on `agent.Monitor()` and `session.RenewPeriodic` methods to make them more compatible with `context`. [[GH-3271](https://github.com/hashicorp/consul/issues/3271)]
* docs: Added a complete end-to-end example of ACL bootstrapping in the [ACL Guide](https://www.consul.io/docs/guides/acl.html#bootstrapping-acls). [[GH-3248](https://github.com/hashicorp/consul/issues/3248)]
* vendor: Updated golang.org/x/sys/unix to support IBM s390 platforms. [[GH-3240](https://github.com/hashicorp/consul/issues/3240)]
* agent: rewrote Docker health checks without using the Docker client and its dependencies. [[GH-3270](https://github.com/hashicorp/consul/issues/3270)]
* agent: Fixed an issue where watch plans would take up to 10 minutes to close their connections and give up their file descriptors after reloading Consul. [[GH-3018](https://github.com/hashicorp/consul/issues/3018)]
* agent: (Consul Enterprise) Fixed an issue with the snapshot agent where it could get stuck trying to obtain the leader lock after an extended server outage.
* agent: Fixed HTTP health checks to allow them to set the `Host` header correctly on outgoing requests. [[GH-3203](https://github.com/hashicorp/consul/issues/3203)]
* agent: Serf snapshots can now auto recover from disk write errors without needing a restart. [[GH-1744](https://github.com/hashicorp/consul/issues/1744)]
* agent: Fixed log redacting code to properly remove tokens from log lines with ACL tokens in the URL itself: `/v1/acl/clone/:uuid`, `/v1/acl/destroy/:uuid`, `/v1/acl/info/:uuid`. [[GH-3276](https://github.com/hashicorp/consul/issues/3276)]
* agent: Fixed an issue in the Docker client where Docker checks would get EOF errors trying to connect to a volume-mounted Docker socket. [[GH-3254](https://github.com/hashicorp/consul/issues/3254)]
* agent: Fixed a crash when using Azure auto discovery. [[GH-3193](https://github.com/hashicorp/consul/issues/3193)]
* agent: Added `node` read privileges to the `acl_agent_master_token` by default so it can see all nodes, which enables it to be used with operations like `consul members`. [[GH-3113](https://github.com/hashicorp/consul/issues/3113)]
* agent: Fixed an issue where enabling [`-disable-keyring-file`](https://www.consul.io/docs/agent/options.html#_disable_keyring_file) would cause gossip encryption to be disabled. [[GH-3243](https://github.com/hashicorp/consul/issues/3243)]
* agent: Fixed a race condition where checks that are not associated with any existing services were allowed to persist. [[GH-3297](https://github.com/hashicorp/consul/issues/3297)]
* server: Updated the Raft library to pull in a fix where servers that are very far behind in replication can get stuck in a loop trying to install snapshots. [[GH-3201](https://github.com/hashicorp/consul/issues/3201)]
* server: Fixed a rare but serious deadlock where the Consul leader routine could get stuck with the Raft internal leader routine while waiting for the initial barrier after a leader election. [[GH-3230](https://github.com/hashicorp/consul/issues/3230)]
* server: Added automatic cleanup of failed Raft snapshots. [[GH-3258](https://github.com/hashicorp/consul/issues/3258)]
* server: (Consul Enterprise) Fixed an issue where networks areas would not be able to be added when the server restarts if the Raft log contained a specific sequence of adds and deletes for network areas with the same peer datacenter.
* ui: Provided a path to reset the ACL token when the current token is invalid. Previously, the UI would get stuck on the error page and it wasn't possible to get back to the settings. [[GH-2370](https://github.com/hashicorp/consul/issues/2370)]
* ui: Removed an extra fetch of the nodes resource when loading the UI. [[GH-3245](https://github.com/hashicorp/consul/issues/3245)]
* ui: Changed default ACL token type to "client" when creating ACLs. [[GH-3246](https://github.com/hashicorp/consul/issues/3246)]
* ui: Display a 404 error instead of a 200 when trying to load a nonexistent node. [[GH-3251](https://github.com/hashicorp/consul/issues/3251)]
* agent: Parse values given to `?passing` for health endpoints. Previously Consul only checked for the existence of the querystring, not the value. That means using `?passing=false` would actually still include passing values. Consul now parses the value given to passing as a boolean. If no value is provided, the old behavior remains. This may be a breaking change for some users, but the old experience was incorrect and caused enough confusion to warrant changing it. [GH-2212, GH-3136]
* agent: The default value of [`-disable-host-node-id`](https://www.consul.io/docs/agent/options.html#_disable_host_node_id) has been changed from false to true. This means you need to opt-in to host-based node IDs and by default Consul will generate a random node ID. A high number of users struggled to deploy newer versions of Consul with host-based IDs because of various edge cases of how the host IDs work in Docker, on specially-provisioned machines, etc. so changing this from opt-out to opt-in will ease operations for many Consul users. [[GH-3171](https://github.com/hashicorp/consul/issues/3171)]
* agent: Added a `-disable-keyring-file` option to prevent writing keyring data to disk. [[GH-3145](https://github.com/hashicorp/consul/issues/3145)]
* agent: Added automatic notify to systemd on Linux after LAN join is complete, which makes it easier to order services that depend on Consul being available. [[GH-2121](https://github.com/hashicorp/consul/issues/2121)]
* agent: The `http_api_response_headers` config has been moved into a new `http_config` struct, so the old form is still supported but is deprecated. [[GH-3142](https://github.com/hashicorp/consul/issues/3142)]
* dns: Added support for EDNS(0) size adjustments if set in the request frame. This allows DNS responses via UDP which are larger than the standard 512 bytes max if the requesting client can support it. [GH-1980, GH-3131]
* server: Added a startup warning for servers when expecting to bootstrap with an even number of nodes. [[GH-1282](https://github.com/hashicorp/consul/issues/1282)]
* agent: Fixed a regression where configuring -1 for the port was no longer disabling the DNS server. [[GH-3135](https://github.com/hashicorp/consul/issues/3135)]
* agent: Fix `consul leave` shutdown race. When shutting down an agent via the `consul leave` command on the command line the output would be `EOF` instead of `Graceful leave completed` [[GH-2880](https://github.com/hashicorp/consul/issues/2880)]
* agent: Show a better error message than 'EOF' when attempting to join with the wrong gossip key. [[GH-1013](https://github.com/hashicorp/consul/issues/1013)]
* agent: Fixed an issue where the `Method` and `Header` features of HTTP health checks were not being applied. [[GH-3178](https://github.com/hashicorp/consul/issues/3178)]
* agent: Fixed an issue where internally-configured watches were not working because of an incorrect protocol error, and unified internal watch handling during reloads of the Consul agent. [[GH-3177](https://github.com/hashicorp/consul/issues/3177)]
* server: Fixed an issue where the leader could return stale data duing queries as it is starting up. [[GH-2644](https://github.com/hashicorp/consul/issues/2644)]
* agent: Added a method for [transitioning to gossip encryption on an existing cluster](https://www.consul.io/docs/agent/encryption.html#configuring-gossip-encryption-on-an-existing-cluster). [[GH-3079](https://github.com/hashicorp/consul/issues/3079)]
* agent: Added a method for [transitioning to TLS on an existing cluster](https://www.consul.io/docs/agent/encryption.html#configuring-tls-on-an-existing-cluster). [[GH-1705](https://github.com/hashicorp/consul/issues/1705)]
* agent: Added support for [RetryJoin on Azure](https://www.consul.io/docs/agent/options.html#retry_join_azure). [[GH-2978](https://github.com/hashicorp/consul/issues/2978)]
* agent: (Consul Enterprise) Added [AWS server side encryption support](http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingServerSideEncryption.html) for S3 snapshots using the snapshot agent.
* agent: Added a check which prevents advertising or setting a service to a zero address (`0.0.0.0`, `[::]`, `::`). [[GH-2961](https://github.com/hashicorp/consul/issues/2961)]
* agent: Allow binding to any public IPv6 address with `::` [[GH-2285](https://github.com/hashicorp/consul/issues/2285)]
* agent: Removed SCADA-related code for Atlas and deprecated all Atlas-related configuration options. [[GH-3032](https://github.com/hashicorp/consul/issues/3032)]
* agent: Added support for custom check id and name when registering checks along with a service. [[GH-3047](https://github.com/hashicorp/consul/issues/3047)]
* agent: Updated [go-sockaddr](https://github.com/hashicorp/go-sockaddr) library to add support for new helper functions in bind address templates (`GetPrivateIPs`, `GetPublicIPs`), new math functions, and to pick up fixes for issues with detecting addresses on multi-homed hosts. [[GH-3068](https://github.com/hashicorp/consul/issues/3068)]
* agent: Watches now reset their index back to zero after an error, or if the index goes backwards, which allows watches to recover after a server restart with fresh state. [[GH-2621](https://github.com/hashicorp/consul/issues/2621)]
* agent: HTTP health checks now support custom method and headers. [[GH-1184](https://github.com/hashicorp/consul/issues/1184)], [[GH-2474](https://github.com/hashicorp/consul/issues/2474)], [[GH-2657](https://github.com/hashicorp/consul/issues/2657)], [[GH-3106](https://github.com/hashicorp/consul/issues/3106)]
* agent: Increased the graceful leave timeout from 5 to 15 seconds. [[GH-3121](https://github.com/hashicorp/consul/issues/3121)]
* agent: Added additional logging when the agent handles signals and when it exits. [[GH-3124](https://github.com/hashicorp/consul/issues/3124)]
* build: Added support for linux/arm64 binaries. [[GH-3042](https://github.com/hashicorp/consul/issues/3042)]
* build: Consul now builds with Go 1.8.3. [[GH-3074](https://github.com/hashicorp/consul/issues/3074)]
* ui: Added a sticky scroll to the KV side panel so the KV edit box always stays in place. [[GH-2812](https://github.com/hashicorp/consul/issues/2812)]
* agent: Added defensive code to prevent agents from infecting the network coordinates with `NaN` or `Inf` values, and added code to clean up in environments where this has happened. [[GH-3023](https://github.com/hashicorp/consul/issues/3023)]
* api: Added code to always read from the body of a request so that connections will always be returned to the pool. [[GH-2850](https://github.com/hashicorp/consul/issues/2850)]
* build: Added a vendor fix to allow compilation on Illumos. [[GH-3024](https://github.com/hashicorp/consul/issues/3024)]
* cli: Fixed an issue where `consul exec` would return a 0 exit code, even when there were nodes that didn't respond. [[GH-2757](https://github.com/hashicorp/consul/issues/2757)]
* agent: Fixed an issue where NAT-configured agents with a non-routable advertise address would refuse to make RPC connections to Consul servers. This was a regression related to GH-2822 in Consul 0.8.2. [[GH-3028](https://github.com/hashicorp/consul/issues/3028)]
* api: HttpClient now defaults to nil in the client config and will be generated if left blank. A NewHttpClient function has been added for creating an HttpClient with a custom Transport or TLS config. [[GH-2922](https://github.com/hashicorp/consul/issues/2922)]
* agent: Added an error at agent startup time if both `-ui` and `-ui-dir` are configured together. [[GH-2576](https://github.com/hashicorp/consul/issues/2576)]
* agent: Added the datacenter of a node to the catalog, health, and query API endpoints which contain a Node structure. [[GH-2713](https://github.com/hashicorp/consul/issues/2713)]
* agent: Added the `ca_path`, `tls_cipher_suites`, and `tls_prefer_server_cipher_suites` options to give more flexibility around configuring TLS. [[GH-2963](https://github.com/hashicorp/consul/issues/2963)]
* agent: Reduced the timeouts for the `-dev` server mode so that the development server starts up almost instantly. [[GH-2984](https://github.com/hashicorp/consul/issues/2984)]
* agent: Added `verify_incoming_rpc` and `verify_incoming_https` options for more granular control over incoming TLS enforcement. [[GH-2974](https://github.com/hashicorp/consul/issues/2974)]
* agent: Use bind address as source for outgoing connections. [[GH-2822](https://github.com/hashicorp/consul/issues/2822)]
* api: Added the ACL replication status endpoint to the Go API client library. [[GH-2947](https://github.com/hashicorp/consul/issues/2947)]
* cli: Added Raft protocol version to output of `operator raft list-peers` command.[[GH-2929](https://github.com/hashicorp/consul/issues/2929)]
* ui: Added optional JSON validation when editing KV entries in the web UI. [[GH-2712](https://github.com/hashicorp/consul/issues/2712)]
* ui: Updated ACL guide links and made guides open in a new tab. [[GH-3010](https://github.com/hashicorp/consul/issues/3010)]
* server: Fixed a panic when the tombstone garbage collector was stopped. [[GH-2087](https://github.com/hashicorp/consul/issues/2087)]
* server: Fixed a panic in Autopilot that could occur when a node is elected but cannot complete leader establishment and steps back down. [[GH-2980](https://github.com/hashicorp/consul/issues/2980)]
* server: Added a new peers.json format that allows outage recovery when using Raft protocol version 3 and higher. Previously, you'd have to set the Raft protocol version back to 2 in order to manually recover a cluster. See https://www.consul.io/docs/guides/outage.html#manual-recovery-using-peers-json for more details. [[GH-3003](https://github.com/hashicorp/consul/issues/3003)]
* ui: Add and update favicons [[GH-2945](https://github.com/hashicorp/consul/issues/2945)]
* agent: Node IDs derived from host information are now hashed to prevent things like common server hardware from generating IDs with a common prefix across nodes. [[GH-2884](https://github.com/hashicorp/consul/issues/2884)]
* agent: Added new `-disable-host-node-id` CLI flag and `disable_host_node_id` config option to the Consul agent to prevent it from using information from the host when generating a node ID. This will result in a random node ID, which is useful when running multiple Consul agents on the same host for testing purposes. Having this built-in eases configuring a random node ID when running in containers. [[GH-2877](https://github.com/hashicorp/consul/issues/2877)]
* agent: Removed useless "==> Caught signal: broken pipe" logging since that often results from problems sending telemetry or broken incoming client connections; operators don't need to be alerted to these. [[GH-2768](https://github.com/hashicorp/consul/issues/2768)]
* cli: Added TLS options for setting the client/CA certificates to use when communicating with Consul. These can be provided through environment variables or command line flags. [[GH-2914](https://github.com/hashicorp/consul/issues/2914)]
* build: Consul is now built with Go 1.8.1. [[GH-2888](https://github.com/hashicorp/consul/issues/2888)]
* ui: Updates Consul assets to new branding. [[GH-2898](https://github.com/hashicorp/consul/issues/2898)]
* api: Added missing Raft index fields to AgentService and Node structures. [[GH-2882](https://github.com/hashicorp/consul/issues/2882)]
* server: Fixed an issue where flood joins would not work with IPv6 addresses. [[GH-2878](https://github.com/hashicorp/consul/issues/2878)]
* server: Fixed an issue where electing a 0.8.x leader during an upgrade would cause a panic in older servers. [[GH-2889](https://github.com/hashicorp/consul/issues/2889)]
* server: Fixed an issue where tracking of leadership changes could become incorrect when changes occurred very rapidly. This could manifest as a panic in Autopilot, but could have caused other issues with multiple leader management routines running simultaneously. [[GH-2896](https://github.com/hashicorp/consul/issues/2896)]
* server: Fixed a panic when checking ACLs on a session that doesn't exist. [[GH-2624](https://github.com/hashicorp/consul/issues/2624)]
* **Command-Line Interface RPC Deprecation:** The RPC client interface has been removed. All CLI commands that used RPC and the `-rpc-addr` flag to communicate with Consul have been converted to use the HTTP API and the appropriate flags for it, and the `rpc` field has been removed from the port and address binding configs. You will need to remove these fields from your config files and update any scripts that passed a custom `-rpc-addr` to the following commands: `force-leave`, `info`, `join`, `keyring`, `leave`, `members`, `monitor`, `reload`
* **Version 8 ACLs Are Now Opt-Out:** The [`acl_enforce_version_8`](https://www.consul.io/docs/agent/options.html#acl_enforce_version_8) configuration now defaults to `true` to enable [full version 8 ACL support](https://www.consul.io/docs/internals/acl.html#version_8_acls) by default. If you are upgrading an existing cluster with ACLs enabled, you will need to set this to `false` during the upgrade on **both Consul agents and Consul servers**. Version 8 ACLs were also changed so that [`acl_datacenter`](https://www.consul.io/docs/agent/options.html#acl_datacenter) must be set on agents in order to enable the agent-side enforcement of ACLs. This makes for a smoother experience in clusters where ACLs aren't enabled at all, but where the agents would have to wait to contact a Consul server before learning that. [[GH-2844](https://github.com/hashicorp/consul/issues/2844)]
* **Remote Exec Is Now Opt-In:** The default for [`disable_remote_exec`](https://www.consul.io/docs/agent/options.html#disable_remote_exec) was changed to "true", so now operators need to opt-in to having agents support running commands remotely via [`consul exec`](/docs/commands/exec.html). [[GH-2854](https://github.com/hashicorp/consul/issues/2854)]
* **Raft Protocol Compatibility:** When upgrading to Consul 0.8.0 from a version lower than 0.7.0, users will need to
set the [`-raft-protocol`](https://www.consul.io/docs/agent/options.html#_raft_protocol) option to 1 in order to maintain backwards compatibility with the old servers during the upgrade. See [Upgrading Specific Versions](https://www.consul.io/docs/upgrade-specific.html) guide for more details.
* **Autopilot:** A set of features has been added to allow for automatic operator-friendly management of Consul servers. For more information about Autopilot, see the [Autopilot Guide](https://www.consul.io/docs/guides/autopilot.html).
- **Dead Server Cleanup:** Dead servers will periodically be cleaned up and removed from the Raft peer set, to prevent them from interfering with the quorum size and leader elections.
- **Server Health Checking:** An internal health check has been added to track the stability of servers. The thresholds of this health check are tunable as part of the [Autopilot configuration](https://www.consul.io/docs/agent/options.html#autopilot) and the status can be viewed through the [`/v1/operator/autopilot/health`](https://www.consul.io/docs/agent/http/operator.html#autopilot-health) HTTP endpoint.
- **New Server Stabilization:** When a new server is added to the cluster, there will be a waiting period where it must be healthy and stable for a certain amount of time before being promoted to a full, voting member. This threshold can be configured using the new [`server_stabilization_time`](https://www.consul.io/docs/agent/options.html#server_stabilization_time) setting.
- **Advanced Redundancy:** (Consul Enterprise) A new [`-non-voting-server`](https://www.consul.io/docs/agent/options.html#_non_voting_server) option flag has been added for Consul servers to configure a server that does not participate in the Raft quorum. This can be used to add read scalability to a cluster in cases where a high volume of reads to servers are needed, but non-voting servers can be lost without causing an outage. There's also a new [`redundancy_zone_tag`](https://www.consul.io/docs/agent/options.html#redundancy_zone_tag) configuration that allows Autopilot to manage separating servers into zones for redundancy. Only one server in each zone can be a voting member at one time. This helps when Consul servers are managed with automatic replacement with a system like a resource scheduler or auto-scaling group. Extra non-voting servers in each zone will be available as hot standbys (that help with read-scaling) that can be quickly promoted into service when the voting server in a zone fails.
- **Upgrade Orchestration:** (Consul Enterprise) Autopilot will automatically orchestrate an upgrade strategy for Consul servers where it will initially add newer versions of Consul servers as non-voters, wait for a full set of newer versioned servers to be added, and then gradually swap into service as voters and swap out older versioned servers to non-voters. This allows operators to safely bring up new servers, wait for the upgrade to be complete, and then terminate the old servers.
* **Network Areas:** (Consul Enterprise) A new capability has been added which allows operators to define network areas that join together two Consul datacenters. Unlike Consul's WAN feature, network areas use just the server RPC port for communication, and pairwise relationships can be made between arbitrary datacenters, so not all servers need to be fully connected. This allows for complex topologies among Consul datacenters like hub/spoke and more general trees. See the [Network Areas Guide](https://www.consul.io/docs/guides/areas.html) for more details.
* **WAN Soft Fail:** Request routing between servers in the WAN is now more robust by treating Serf failures as advisory but not final. This means that if there are issues between some subset of the servers in the WAN, Consul will still be able to route RPC requests as long as RPCs are actually still working. Prior to WAN Soft Fail, any datacenters having connectivity problems on the WAN would mean that all DCs might potentially stop sending RPCs to those datacenters. [[GH-2801](https://github.com/hashicorp/consul/issues/2801)]
* **WAN Join Flooding:** A new routine was added that looks for Consul servers in the LAN and makes sure that they are joined into the WAN as well. This catches up up newly-added servers onto the WAN as soon as they join the LAN, keeping them in sync automatically. [[GH-2801](https://github.com/hashicorp/consul/issues/2801)]
* **Validate command:** To provide consistency across our products, the `configtest` command has been deprecated and replaced with the `validate` command (to match Nomad and Terraform). The `configtest` command will be removed in Consul 0.9. [[GH-2732](https://github.com/hashicorp/consul/issues/2732)]
* agent: Fixed a missing case where gossip would stop flowing to dead nodes for a short while. [[GH-2722](https://github.com/hashicorp/consul/issues/2722)]
* agent: Changed agent to seed Go's random number generator. [[GH-2722](https://github.com/hashicorp/consul/issues/2722)]
* agent: Serf snapshots no longer have the executable bit set on the file. [[GH-2722](https://github.com/hashicorp/consul/issues/2722)]
* agent: Consul is now built with Go 1.8. [[GH-2752](https://github.com/hashicorp/consul/issues/2752)]
* agent: Updated aws-sdk-go version (used for EC2 auto join) for Go 1.8 compatibility. [[GH-2755](https://github.com/hashicorp/consul/issues/2755)]
* agent: User-supplied node IDs are now normalized to lower-case. [[GH-2798](https://github.com/hashicorp/consul/issues/2798)]
* agent: Added checks to enforce uniqueness of agent node IDs at cluster join time and when registering with the catalog. [[GH-2832](https://github.com/hashicorp/consul/issues/2832)]
* cli: Standardized handling of CLI options for connecting to the Consul agent. This makes sure that the same set of flags and environment variables works in all CLI commands (see https://www.consul.io/docs/commands/index.html#environment-variables). [[GH-2717](https://github.com/hashicorp/consul/issues/2717)]
* cli: Updated go-cleanhttp library for better HTTP connection handling between CLI commands and the Consul agent (tunes reuse settings). [[GH-2735](https://github.com/hashicorp/consul/issues/2735)]
* cli: The `operator raft` subcommand has had its two modes split into the `list-peers` and `remove-peer` subcommands. The old flags for these will continue to work for backwards compatibility, but will be removed in Consul 0.9.
* cli: Added an `-id` flag to the `operator raft remove-peer` command to allow removing a peer by ID. [[GH-2847](https://github.com/hashicorp/consul/issues/2847)]
* dns: Allows the `.service` tag to be optional in RFC 2782 lookups. [[GH-2690](https://github.com/hashicorp/consul/issues/2690)]
* server: Changed the internal `EnsureRegistration` RPC endpoint to prevent registering checks that aren't associated with the top-level node being registered. [[GH-2846](https://github.com/hashicorp/consul/issues/2846)]
* agent: Fixed an issue with `consul watch` not working when http was listening on a unix socket. [[GH-2385](https://github.com/hashicorp/consul/issues/2385)]
* agent: Fixed an issue where checks and services could not sync deregister operations back to the catalog when version 8 ACL support is enabled. [[GH-2818](https://github.com/hashicorp/consul/issues/2818)]
* agent: Fixed an issue where agents could use the ACL token registered with a service when registering checks for the same service that were registered with a different ACL token. [[GH-2829](https://github.com/hashicorp/consul/issues/2829)]
* cli: Fixed `consul kv` commands not reading the `CONSUL_HTTP_TOKEN` environment variable. [[GH-2566](https://github.com/hashicorp/consul/issues/2566)]
* cli: Fixed an issue where prefixing an address with a protocol (such as 'http://' or 'https://') in `-http-addr` or `CONSUL_HTTP_ADDR` would give an error.
* cli: Fixed an issue where error messages would get printed to stdout instead of stderr. [[GH-2548](https://github.com/hashicorp/consul/issues/2548)]
* server: Fixed an issue with version 8 ACLs where servers couldn't deregister nodes from the catalog during reconciliation. [[GH-2792](https://github.com/hashicorp/consul/issues/2792)] This fix was generalized and applied to registering nodes as well. [[GH-2826](https://github.com/hashicorp/consul/issues/2826)]
* server: Fixed an issue where servers could temporarily roll back changes to a node's metadata or tagged addresses when making updates to the node's health checks. [[GH-2826](https://github.com/hashicorp/consul/issues/2826)]
* server: Fixed an issue where the service name `consul` was not subject to service ACL policies with version 8 ACLs enabled. [[GH-2816](https://github.com/hashicorp/consul/issues/2816)]
* server: Fixed a rare but serious issue where Consul servers could panic when performing a large delete operation followed by a specific sequence of other updates to related parts of the state store (affects KV, sessions, prepared queries, and the catalog). [[GH-2724](https://github.com/hashicorp/consul/issues/2724)]
* agent: Integrated gopsutil library to use built in host UUID as node ID, if available, instead of a randomly generated UUID. This makes it easier for other applications on the same host to generate the same node ID without coordinating with Consul. [[GH-2697](https://github.com/hashicorp/consul/issues/2697)]
* agent: Added a configuration option, `tls_min_version`, for setting the minimum allowed TLS version used for the HTTP API and RPC. [[GH-2699](https://github.com/hashicorp/consul/issues/2699)]
* agent: Added a `relay-factor` option to keyring operations to allow nodes to relay their response through N randomly-chosen other nodes in the cluster. [[GH-2704](https://github.com/hashicorp/consul/issues/2704)]
* build: Consul is now built with Go 1.7.5. [[GH-2682](https://github.com/hashicorp/consul/issues/2682)]
* dns: Add ability to lookup Consul agents by either their Node ID or Node Name through the node interface (e.g. DNS `(node-id|node-name).node.consul`). [[GH-2702](https://github.com/hashicorp/consul/issues/2702)]
* dns: Fixed an issue where SRV lookups for services on a node registered with non-IP addresses were missing the CNAME record in the additional section of the response. [[GH-2695](https://github.com/hashicorp/consul/issues/2695)]
* **KV Import/Export CLI:** `consul kv export` and `consul kv import` can be used to move parts of the KV tree between disconnected consul clusters, using JSON as the intermediate representation. [[GH-2633](https://github.com/hashicorp/consul/issues/2633)]
* **Node Metadata:** Support for assigning user-defined metadata key/value pairs to nodes has been added. This can be viewed when looking up node info, and can be used to filter the results of various catalog and health endpoints. For more information, see the [Catalog](https://www.consul.io/docs/agent/http/catalog.html), [Health](https://www.consul.io/docs/agent/http/health.html), and [Prepared Query](https://www.consul.io/docs/agent/http/query.html) endpoint documentation, as well as the [Node Meta](https://www.consul.io/docs/agent/options.html#_node_meta) section of the agent configuration. [[GH-2654](https://github.com/hashicorp/consul/issues/2654)]
* **Node Identifiers:** Consul agents can now be configured with a unique identifier, or they will generate one at startup that will persist across agent restarts. This identifier is designed to represent a node across all time, even if the name or address of the node changes. Identifiers are currently only exposed in node-related endpoints, but they will be used in future versions of Consul to help manage Consul servers and the Raft quorum in a more robust manner, as the quorum is currently tracked via addresses, which can change. [[GH-2661](https://github.com/hashicorp/consul/issues/2661)]
* **Improved Blocking Queries:** Consul's [blocking query](https://www.consul.io/api/index.html#blocking-queries) implementation was improved to provide a much more fine-grained mechanism for detecting changes. For example, in previous versions of Consul blocking to wait on a change to a specific service would result in a wake up if any service changed. Now, wake ups are scoped to the specific service being watched, if possible. This support has been added to all endpoints that support blocking queries, nothing new is required to take advantage of this feature. [[GH-2671](https://github.com/hashicorp/consul/issues/2671)]
* **GCE auto-discovery:** New `-retry-join-gce` configuration options added to allow bootstrapping by automatically discovering Google Cloud instances with a given tag at startup. [[GH-2570](https://github.com/hashicorp/consul/issues/2570)]
* build: Consul is now built with Go 1.7.4. [[GH-2676](https://github.com/hashicorp/consul/issues/2676)]
* cli: `consul kv get` now has a `-base64` flag to base 64 encode the value. [[GH-2631](https://github.com/hashicorp/consul/issues/2631)]
* cli: `consul kv put` now has a `-base64` flag for setting values which are base 64 encoded. [[GH-2632](https://github.com/hashicorp/consul/issues/2632)]
* ui: Added a notice that JS is required when viewing the web UI with JS disabled. [[GH-2636](https://github.com/hashicorp/consul/issues/2636)]
* agent: Redacted the AWS access key and secret key ID from the /v1/agent/self output so they are not disclosed. [[GH-2677](https://github.com/hashicorp/consul/issues/2677)]
* agent: Fixed a rare startup panic due to a Raft/Serf race condition. [[GH-1899](https://github.com/hashicorp/consul/issues/1899)]
* cli: Fixed a panic when an empty quoted argument was given to `consul kv put`. [[GH-2635](https://github.com/hashicorp/consul/issues/2635)]
* tests: Fixed a race condition with check mock's map usage. [[GH-2578](https://github.com/hashicorp/consul/issues/2578)]
* **Keyring API:** A new `/v1/operator/keyring` HTTP endpoint was added that allows for performing operations such as list, install, use, and remove on the encryption keys in the gossip keyring. See the [Keyring Endpoint](https://www.consul.io/docs/agent/http/operator.html#keyring) for more details. [[GH-2509](https://github.com/hashicorp/consul/issues/2509)]
* **Monitor API:** A new `/v1/agent/monitor` HTTP endpoint was added to allow for viewing streaming log output from the agent, similar to the `consul monitor` command. See the [Monitor Endpoint](https://www.consul.io/docs/agent/http/agent.html#agent_monitor) for more details. [[GH-2511](https://github.com/hashicorp/consul/issues/2511)]
* **Reload API:** A new `/v1/agent/reload` HTTP endpoint was added for triggering a reload of the agent's configuration. See the [Reload Endpoint](https://www.consul.io/docs/agent/http/agent.html#agent_reload) for more details. [[GH-2516](https://github.com/hashicorp/consul/issues/2516)]
* **Leave API:** A new `/v1/agent/leave` HTTP endpoint was added for causing an agent to gracefully shutdown and leave the cluster (previously, only `force-leave` was present in the HTTP API). See the [Leave Endpoint](https://www.consul.io/docs/agent/http/agent.html#agent_leave) for more details. [[GH-2516](https://github.com/hashicorp/consul/issues/2516)]
* **Bind Address Templates (beta):** Consul agents now allow [go-sockaddr/template](https://godoc.org/github.com/hashicorp/go-sockaddr/template) syntax to be used for any bind address configuration (`advertise_addr`, `bind_addr`, `client_addr`, and others). This allows for easy creation of immutable images for Consul that can fetch their own address based on an interface name, network CIDR, address family from an actual RFC number, and many other possible schemes. This feature is in beta and we may tweak the template syntax before final release, but we encourage the community to try this and provide feedback. [[GH-2563](https://github.com/hashicorp/consul/issues/2563)]
* **Complete ACL Coverage (beta):** Consul 0.8 will feature complete ACL coverage for all of Consul. To ease the transition to the new policies, a beta version of complete ACL support was added to help with testing and migration to the new features. Please see the [ACLs Internals Guide](https://www.consul.io/docs/internals/acl.html#version_8_acls) for more details. [GH-2594, GH-2592, GH-2590]
* agent: Defaults to `?pretty` JSON for HTTP API requests when in `-dev` mode. [[GH-2518](https://github.com/hashicorp/consul/issues/2518)]
* agent: Updated Circonus metrics library and added new Circonus configration options for Consul for customizing check display name and tags. [[GH-2555](https://github.com/hashicorp/consul/issues/2555)]
* agent: Added a checksum to UDP gossip messages to guard against packet corruption. [[GH-2574](https://github.com/hashicorp/consul/issues/2574)]
* agent: Check whether a snapshot needs to be taken more often (every 5 seconds instead of 2 minutes) to keep the raft file smaller and to avoid doing huge truncations when writing lots of entries very quickly. [[GH-2591](https://github.com/hashicorp/consul/issues/2591)]
* agent: Allow gossiping to suspected/recently dead nodes. [[GH-2593](https://github.com/hashicorp/consul/issues/2593)]
* agent: Changed the gossip suspicion timeout to grow smoothly as the number of nodes grows. [[GH-2593](https://github.com/hashicorp/consul/issues/2593)]
* agent: Added a deprecation notice for Atlas features to the CLI and docs. [[GH-2597](https://github.com/hashicorp/consul/issues/2597)]
* agent: Give a better error message when the given data-dir is not a directory. [[GH-2529](https://github.com/hashicorp/consul/issues/2529)]
* agent: Fixed a panic when SIGPIPE signal was received. [[GH-2404](https://github.com/hashicorp/consul/issues/2404)]
* api: Added missing Raft index fields to `CatalogService` structure. [[GH-2366](https://github.com/hashicorp/consul/issues/2366)]
* api: Added missing notes field to `AgentServiceCheck` structure. [[GH-2336](https://github.com/hashicorp/consul/issues/2336)]
* api: Changed type of `AgentServiceCheck.TLSSkipVerify` from `string` to `bool`. [[GH-2530](https://github.com/hashicorp/consul/issues/2530)]
* api: Added new `HealthChecks.AggregatedStatus()` method that makes it easy get an overall health status from a list of checks. [[GH-2544](https://github.com/hashicorp/consul/issues/2544)]
* api: Changed type of `KVTxnOp.Verb` from `string` to `KVOp`. [[GH-2531](https://github.com/hashicorp/consul/issues/2531)]
* cli: Fixed an issue with the `consul kv put` command where a negative value would be interpreted as an argument to read from standard input. [[GH-2526](https://github.com/hashicorp/consul/issues/2526)]
* ui: Fixed an issue where extra commas would be shown around service tags. [[GH-2340](https://github.com/hashicorp/consul/issues/2340)]
* ui: Customized Bootstrap config to avoid missing font file references. [[GH-2485](https://github.com/hashicorp/consul/issues/2485)]
* ui: Removed "Deregister" button as removing nodes from the catalog isn't a common operation and leads to lots of user confusion. [[GH-2541](https://github.com/hashicorp/consul/issues/2541)]
* Child process reaping support has been removed, along with the `reap` configuration option. Reaping is also done via [dumb-init](https://github.com/Yelp/dumb-init) in the [Consul Docker image](https://github.com/hashicorp/docker-consul), so removing it from Consul itself simplifies the code and eases future maintainence for Consul. If you are running Consul as PID 1 in a container you will need to arrange for a wrapper process to reap child processes. [[GH-1988](https://github.com/hashicorp/consul/issues/1988)]
* The default for `max_stale` has been increased to a near-indefinite threshold (10 years) to allow DNS queries to continue to be served in the event of a long outage with no leader. A new telemetry counter has also been added at `consul.dns.stale_queries` to track when agents serve DNS queries that are over a certain staleness (>5 seconds). [[GH-2481](https://github.com/hashicorp/consul/issues/2481)]
* The api package's `PreparedQuery.Delete()` method now takes `WriteOptions` instead of `QueryOptions`. [[GH-2417](https://github.com/hashicorp/consul/issues/2417)]
* **Key/Value Store Command Line Interface:** New `consul kv` commands were added for easy access to all basic key/value store operations. [[GH-2360](https://github.com/hashicorp/consul/issues/2360)]
* **Snapshot/Restore:** A new /v1/snapshot HTTP endpoint and corresponding set of `consul snapshot` commands were added for easy point-in-time snapshots for disaster recovery. Snapshots include all state managed by Consul's Raft [consensus protocol](/docs/internals/consensus.html), including Key/Value Entries, Service Catalog, Prepared Queries, Sessions, and ACLs. Snapshots can be restored on the fly into a completely fresh cluster. [[GH-2396](https://github.com/hashicorp/consul/issues/2396)]
* **AWS auto-discovery:** New `-retry-join-ec2` configuration options added to allow bootstrapping by automatically discovering AWS instances with a given tag key/value at startup. [[GH-2459](https://github.com/hashicorp/consul/issues/2459)]
* api: All session options can now be set when using `api.Lock()`. [[GH-2372](https://github.com/hashicorp/consul/issues/2372)]
* agent: Added the ability to bind Serf WAN and LAN to different interfaces than the general bind address. [[GH-2007](https://github.com/hashicorp/consul/issues/2007)]
* agent: Added a new `tls_skip_verify` configuration option for HTTP checks. [[GH-1984](https://github.com/hashicorp/consul/issues/1984)]
* build: Consul is now built with Go 1.7.3. [[GH-2281](https://github.com/hashicorp/consul/issues/2281)]
* agent: Fixed a Go race issue with log buffering at startup. [[GH-2262](https://github.com/hashicorp/consul/issues/2262)]
* agent: Fixed a panic during anti-entropy sync for services and checks. [[GH-2125](https://github.com/hashicorp/consul/issues/2125)]
* agent: Fixed an issue on Windows where "wsarecv" errors were logged when CLI commands accessed the RPC interface. [[GH-2356](https://github.com/hashicorp/consul/issues/2356)]
* agent: Syslog initialization will now retry on errors for up to 60 seconds to avoid a race condition at system startup. [[GH-1610](https://github.com/hashicorp/consul/issues/1610)]
* agent: Fixed a panic when both -dev and -bootstrap-expect flags were provided. [[GH-2464](https://github.com/hashicorp/consul/issues/2464)]
* agent: Added a retry with backoff when a session fails to invalidate after expiring. [[GH-2435](https://github.com/hashicorp/consul/issues/2435)]
* agent: Fixed an issue where Consul would fail to start because of leftover malformed check/service state files. [[GH-1221](https://github.com/hashicorp/consul/issues/1221)]
* agent: Log a warning instead of success when attempting to deregister a nonexistent service. [[GH-2492](https://github.com/hashicorp/consul/issues/2492)]
* api: Trim leading slashes from keys/prefixes when querying KV endpoints to avoid a bug with redirects in Go 1.7 (golang/go#4800). [[GH-2403](https://github.com/hashicorp/consul/issues/2403)]
* dns: Fixed external services that pointed to consul addresses (CNAME records) not resolving to A-records. [[GH-1228](https://github.com/hashicorp/consul/issues/1228)]
* dns: Fixed an issue with SRV lookups where the service address was different from the node's. [[GH-832](https://github.com/hashicorp/consul/issues/832)]
* dns: Fixed an issue where truncated records from a recursor query were improperly reported as errors. [[GH-2384](https://github.com/hashicorp/consul/issues/2384)]
* server: Fixed the port numbers in the sample JSON inside peers.info. [[GH-2391](https://github.com/hashicorp/consul/issues/2391)]
* The default behavior of `leave_on_terminate` and `skip_leave_on_interrupt` are now dependent on whether or not the agent is acting as a server or client. When Consul is started as a server the defaults for these are `false` and `true`, respectively, which means that you have to explicitly configure a server to leave the cluster. When Consul is started as a client the defaults are the opposite, which means by default, clients will leave the cluster if shutdown or interrupted. [[GH-1909](https://github.com/hashicorp/consul/issues/1909)] [[GH-2320](https://github.com/hashicorp/consul/issues/2320)]
* The `allow_stale` configuration for DNS queries to the Consul agent now defaults to `true`, allowing for better utilization of available Consul servers and higher throughput at the expense of weaker consistency. This is almost always an acceptable tradeoff for DNS queries, but this can be reconfigured to use the old default behavior if desired. [[GH-2315](https://github.com/hashicorp/consul/issues/2315)]
* Output from HTTP checks is truncated to 4k when stored on the servers, similar to script check output. [[GH-1952](https://github.com/hashicorp/consul/issues/1952)]
* Consul's Go API client will now send ACL tokens using HTTP headers instead of query parameters, requiring Consul 0.6.0 or later. [[GH-2233](https://github.com/hashicorp/consul/issues/2233)]
* Removed support for protocol version 1, so Consul 0.7 is no longer compatible with Consul versions prior to 0.3. [[GH-2259](https://github.com/hashicorp/consul/issues/2259)]
* The Raft peers information in `consul info` has changed format and includes information about the suffrage of a server, which will be used in future versions of Consul. [[GH-2222](https://github.com/hashicorp/consul/issues/2222)]
* New [`translate_wan_addrs`](https://www.consul.io/docs/agent/options.html#translate_wan_addrs) behavior from [[GH-2118](https://github.com/hashicorp/consul/issues/2118)] translates addresses in HTTP responses and could break clients that are expecting local addresses. A new `X-Consul-Translate-Addresses` header was added to allow clients to detect if translation is enabled for HTTP responses, and a "lan" tag was added to `TaggedAddresses` for clients that need the local address regardless of translation. [[GH-2280](https://github.com/hashicorp/consul/issues/2280)]
* The behavior of the `peers.json` file is different in this version of Consul. This file won't normally be present and is used only during outage recovery. Be sure to read the updated [Outage Recovery Guide](https://www.consul.io/docs/guides/outage.html) for details. [[GH-2222](https://github.com/hashicorp/consul/issues/2222)]
* Consul's default Raft timing is now set to work more reliably on lower-performance servers, which allows small clusters to use lower cost compute at the expense of reduced performance for failed leader detection and leader elections. You will need to configure Consul to get the same performance as before. See the new [Server Performance](https://www.consul.io/docs/guides/performance.html) guide for more details. [[GH-2303](https://github.com/hashicorp/consul/issues/2303)]
* **Transactional Key/Value API:** A new `/v1/txn` API was added that allows for atomic updates to and fetches from multiple entries in the key/value store inside of an atomic transaction. This includes conditional updates based on obtaining locks, and all other key/value store operations. See the [Key/Value Store Endpoint](https://www.consul.io/docs/agent/http/kv.html#txn) for more details. [[GH-2028](https://github.com/hashicorp/consul/issues/2028)]
* **Native ACL Replication:** Added a built-in full replication capability for ACLs. Non-ACL datacenters can now replicate the complete ACL set locally to their state store and fall back to that if there's an outage. Additionally, this provides a good way to make a backup ACL datacenter, or to migrate the ACL datacenter to a different one. See the [ACL Internals Guide](https://www.consul.io/docs/internals/acl.html#replication) for more details. [[GH-2237](https://github.com/hashicorp/consul/issues/2237)]
* **Server Connection Rebalancing:** Consul agents will now periodically reconnect to available Consul servers in order to redistribute their RPC query load. Consul clients will, by default, attempt to establish a new connection every 120s to 180s unless the size of the cluster is sufficiently large. The rate at which agents begin to query new servers is proportional to the size of the Consul cluster (servers should never receive more than 64 new connections per second per Consul server as a result of rebalancing). Clusters in stable environments who use `allow_stale` should see a more even distribution of query load across all of their Consul servers. [[GH-1743](https://github.com/hashicorp/consul/issues/1743)]
* **Raft Updates and Consul Operator Interface:** This version of Consul upgrades to "stage one" of the v2 HashiCorp Raft library. This version offers improved handling of cluster membership changes and recovery after a loss of quorum. This version also provides a foundation for new features that will appear in future Consul versions once the remainder of the v2 library is complete. [[GH-2222](https://github.com/hashicorp/consul/issues/2222)] <br> Consul's default Raft timing is now set to work more reliably on lower-performance servers, which allows small clusters to use lower cost compute at the expense of reduced performance for failed leader detection and leader elections. You will need to configure Consul to get the same performance as before. See the new [Server Performance](https://www.consul.io/docs/guides/performance.html) guide for more details. [[GH-2303](https://github.com/hashicorp/consul/issues/2303)] <br> Servers will now abort bootstrapping if they detect an existing cluster with configured Raft peers. This will help prevent safe but spurious leader elections when introducing new nodes with `bootstrap_expect` enabled into an existing cluster. [[GH-2319](https://github.com/hashicorp/consul/issues/2319)] <br> Added new `consul operator` command, HTTP endpoint, and associated ACL to allow Consul operators to view and update the Raft configuration. This allows a stale server to be removed from the Raft peers without requiring downtime and peers.json recovery file use. See the new [Consul Operator Command](https://www.consul.io/docs/commands/operator.html) and the [Consul Operator Endpoint](https://www.consul.io/docs/agent/http/operator.html) for details, as well as the updated [Outage Recovery Guide](https://www.consul.io/docs/guides/outage.html). [[GH-2312](https://github.com/hashicorp/consul/issues/2312)]
* **Serf Lifeguard Updates:** Implemented a new set of feedback controls for the gossip layer that help prevent degraded nodes that can't meet the soft real-time requirements from erroneously causing `serfHealth` flapping in other, healthy nodes. This feature tunes itself automatically and requires no configuration. [[GH-2101](https://github.com/hashicorp/consul/issues/2101)]
* **Prepared Query Near Parameter:** Prepared queries support baking in a new `Near` sorting parameter. This allows results to be sorted by network round trip time based on a static node, or based on the round trip time from the Consul agent where the request originated. This can be used to find a co-located service instance is one is available, with a transparent fallback to the next best alternate instance otherwise. [[GH-2137](https://github.com/hashicorp/consul/issues/2137)]
* **Automatic Service Deregistration:** Added a new `deregister_critical_service_after` timeout field for health checks which will cause the service associated with that check to get deregistered if the check is critical for longer than the timeout. This is useful for cleanup of health checks registered natively by applications, or in other situations where services may not always be cleanly shutdown. [[GH-679](https://github.com/hashicorp/consul/issues/679)]
* **WAN Address Translation Everywhere:** Extended the [`translate_wan_addrs`](https://www.consul.io/docs/agent/options.html#translate_wan_addrs) config option to also translate node addresses in HTTP responses, making it easy to use this feature from non-DNS clients. [[GH-2118](https://github.com/hashicorp/consul/issues/2118)]
* **RPC Retries:** Consul will now retry RPC calls that result in "no leader" errors for up to 5 seconds. This allows agents to ride out leader elections with a delayed response vs. an error. [[GH-2175](https://github.com/hashicorp/consul/issues/2175)]
* **Circonus Telemetry Support:** Added support for Circonus as a telemetry destination. [[GH-2193](https://github.com/hashicorp/consul/issues/2193)]
* agent: Reap time for failed nodes is now configurable via new `reconnect_timeout` and `reconnect_timeout_wan` config options ([use with caution](https://www.consul.io/docs/agent/options.html#reconnect_timeout)). [[GH-1935](https://github.com/hashicorp/consul/issues/1935)]
* agent: Joins based on a DNS lookup will use TCP and attempt to join with the full list of returned addresses. [[GH-2101](https://github.com/hashicorp/consul/issues/2101)]
* agent: Consul will now refuse to start with a helpful message if the same UNIX socket is used for more than one listening endpoint. [[GH-1910](https://github.com/hashicorp/consul/issues/1910)]
* agent: Removed an obsolete warning message when Consul starts on Windows. [[GH-1920](https://github.com/hashicorp/consul/issues/1920)]
* agent: Defaults bind address to 127.0.0.1 when running in `-dev` mode. [[GH-1878](https://github.com/hashicorp/consul/issues/1878)]
* agent: Added version information to the log when Consul starts up. [[GH-1404](https://github.com/hashicorp/consul/issues/1404)]
* agent: Added timing metrics for HTTP requests in the form of `consul.http.<verb>.<path>`. [[GH-2256](https://github.com/hashicorp/consul/issues/2256)]
* build: Updated all vendored dependencies. [[GH-2258](https://github.com/hashicorp/consul/issues/2258)]
* build: Consul releases are now built with Go 1.6.3. [[GH-2260](https://github.com/hashicorp/consul/issues/2260)]
* checks: Script checks now support an optional `timeout` parameter. [[GH-1762](https://github.com/hashicorp/consul/issues/1762)]
* checks: HTTP health checks limit saved output to 4K to avoid performance issues. [[GH-1952](https://github.com/hashicorp/consul/issues/1952)]
* cli: Added a `-stale` mode for watchers to allow them to pull data from any Consul server, not just the leader. [[GH-2045](https://github.com/hashicorp/consul/issues/2045)] [[GH-917](https://github.com/hashicorp/consul/issues/917)]
* dns: Consul agents can now limit the number of UDP answers returned via the DNS interface. The default number of UDP answers is `3`, however by adjusting the `dns_config.udp_answer_limit` configuration parameter, it is now possible to limit the results down to `1`. This tunable provides environments where RFC3484 section 6, rule 9 is enforced with an important workaround in order to preserve the desired behavior of randomized DNS results. Most modern environments will not need to adjust this setting as this RFC was made obsolete by RFC 6724\. See the [agent options](https://www.consul.io/docs/agent/options.html#udp_answer_limit) documentation for additional details for when this should be used. [[GH-1712](https://github.com/hashicorp/consul/issues/1712)]
* dns: Consul now compresses all DNS responses by default. This prevents issues when recursing records that were originally compressed, where Consul would sometimes generate an invalid, uncompressed response that was too large. [[GH-2266](https://github.com/hashicorp/consul/issues/2266)]
* dns: Added a new `recursor_timeout` configuration option to set the timeout for Consul's internal DNS client that's used for recursing queries to upstream DNS servers. [[GH-2321](https://github.com/hashicorp/consul/issues/2321)]
* dns: Added a new `-dns-port` command line option so this can be set without a config file. [[GH-2263](https://github.com/hashicorp/consul/issues/2263)]
* ui: Added a new network tomography visualization to the UI. [[GH-2046](https://github.com/hashicorp/consul/issues/2046)]
* agent: Fixed an issue where a health check's output never updates if the check status doesn't change after the Consul agent starts. [[GH-1934](https://github.com/hashicorp/consul/issues/1934)]
* agent: External services can now be registered with ACL tokens. [[GH-1738](https://github.com/hashicorp/consul/issues/1738)]
* agent: Fixed an issue where large events affecting many nodes could cause infinite intent rebroadcasts, leading to many log messages about intent queue overflows. [[GH-1062](https://github.com/hashicorp/consul/issues/1062)]
* agent: Gossip encryption keys are now validated before being made persistent in the keyring, avoiding delayed feedback at runtime. [[GH-1299](https://github.com/hashicorp/consul/issues/1299)]
* dns: Fixed an issue where DNS requests for SRV records could be incorrectly trimmed, resulting in an ADDITIONAL section that was out of sync with the ANSWER. [[GH-1931](https://github.com/hashicorp/consul/issues/1931)]
* dns: Fixed two issues where DNS requests for SRV records on a prepared query that failed over would report the wrong domain and fail to translate addresses. [[GH-2218](https://github.com/hashicorp/consul/issues/2218)] [[GH-2220](https://github.com/hashicorp/consul/issues/2220)]
* server: Fixed a deadlock related to sorting the list of available datacenters by round trip time. [[GH-2130](https://github.com/hashicorp/consul/issues/2130)]
* server: Fixed an issue with the state store's immutable radix tree that would prevent it from using cached modified objects during transactions, leading to extra copies and increased memory / GC pressure. [[GH-2106](https://github.com/hashicorp/consul/issues/2106)]
* server: Upgraded Bolt DB to v1.2.1 to fix an issue on Windows where Consul would sometimes fail to start due to open user-mapped sections. [[GH-2203](https://github.com/hashicorp/consul/issues/2203)]
Consul to avoid conflicts with other packages [[GH-1310](https://github.com/hashicorp/consul/issues/1310)] [[GH-1327](https://github.com/hashicorp/consul/issues/1327)]
allow registrations before upgrading to prevent a service disruption. [[GH-506](https://github.com/hashicorp/consul/issues/506)] [[GH-465](https://github.com/hashicorp/consul/issues/465)]
failure detector (health check), but are managed by the servers. [[GH-524](https://github.com/hashicorp/consul/issues/524)] [[GH-172](https://github.com/hashicorp/consul/issues/172)]
address that is different from the agent. [[GH-229](https://github.com/hashicorp/consul/issues/229)] [[GH-570](https://github.com/hashicorp/consul/issues/570)]
* Support KV Delete with Check-And-Set [[GH-589](https://github.com/hashicorp/consul/issues/589)]
* Support for distributed locks and semaphores in API client [[GH-594](https://github.com/hashicorp/consul/issues/594)] [[GH-600](https://github.com/hashicorp/consul/issues/600)]
* Support for native HTTP health checks [[GH-592](https://github.com/hashicorp/consul/issues/592)]
* Support for node and service maintenance modes [[GH-606](https://github.com/hashicorp/consul/issues/606)]
* Added new "consul maint" command to easily toggle maintenance modes [[GH-625](https://github.com/hashicorp/consul/issues/625)]
without the applications being Consul aware. [[GH-619](https://github.com/hashicorp/consul/issues/619)]
* Multiple checks can be associated with a service [[GH-591](https://github.com/hashicorp/consul/issues/591)] [[GH-230](https://github.com/hashicorp/consul/issues/230)]
* Added configuration to set custom HTTP headers (CORS) [[GH-558](https://github.com/hashicorp/consul/issues/558)]
* Reject invalid configurations to simplify validation [[GH-576](https://github.com/hashicorp/consul/issues/576)]
* Guard against accidental cluster mixing [[GH-580](https://github.com/hashicorp/consul/issues/580)] [[GH-260](https://github.com/hashicorp/consul/issues/260)]
* Added option to filter DNS results on warning [[GH-595](https://github.com/hashicorp/consul/issues/595)]
* Improve write throughput with raft log caching [[GH-604](https://github.com/hashicorp/consul/issues/604)]
* Added ability to bind RPC and HTTP listeners to UNIX sockets [[GH-587](https://github.com/hashicorp/consul/issues/587)] [[GH-612](https://github.com/hashicorp/consul/issues/612)]
* Use "critical" health state instead of "unknown" [[GH-341](https://github.com/hashicorp/consul/issues/341)]
* Consul service can be targeted for exec [[GH-344](https://github.com/hashicorp/consul/issues/344)]
* Provide debug logging for session invalidation [[GH-390](https://github.com/hashicorp/consul/issues/390)]
* Added "Deregister" button to UI [[GH-364](https://github.com/hashicorp/consul/issues/364)]
* Added `enable_truncate` DNS configuration flag [[GH-376](https://github.com/hashicorp/consul/issues/376)]
* Reduce mmap() size on 32bit systems [[GH-265](https://github.com/hashicorp/consul/issues/265)]
* Temporary state is cleaned after an abort [[GH-338](https://github.com/hashicorp/consul/issues/338)] [[GH-178](https://github.com/hashicorp/consul/issues/178)]
