* **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, you will need to set this to `false` during the upgrade on **both Consul agents and Consul servers**.
* **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 full connected. This allows for complex topologies among Consul datacenters like hub/spoke and more general trees.
* **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]
* **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]
* **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]
* 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]
* 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.
* 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]
* 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]
* 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.
* server: Fixed an issue with version 8 ACLs where servers couldn't deregister nodes from the catalog during reconciliation. [GH-2792] This fix was generalized and applied to registering nodes as well. [GH-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]
* 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]
* 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]
* 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]
* 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]
* 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]
* **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]
* **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]
* **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]
* **Improved Blocking Queries:** Consul's [blocking query](https://www.consul.io/docs/agent/http.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]
* **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]
* **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]
* **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]
* **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]
* **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]
* **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]
* **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: Updated Circonus metrics library and added new Circonus configration options for Consul for customizing check display name and tags. [GH-2555]
* 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]
* 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]
* 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]
* 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]
* **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]
* **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]
* 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] [GH-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]
* Output from HTTP checks is truncated to 4k when stored on the servers, similar to script check output. [GH-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]
* Removed support for protocol version 1, so Consul 0.7 is no longer compatible with Consul versions prior to 0.3. [GH-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]
* New [`translate_wan_addrs`](https://www.consul.io/docs/agent/options.html#translate_wan_addrs) behavior from [GH-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]
* 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]
* 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]
* **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]
* **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]
* **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]
* **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] <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] <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] <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]
* **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]
* **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]
* **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]
* **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]
* **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]
* **Circonus Telemetry Support:** Added support for Circonus as a telemetry destination. [GH-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]
* agent: Joins based on a DNS lookup will use TCP and attempt to join with the full list of returned addresses. [GH-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]
* agent: Removed an obsolete warning message when Consul starts on Windows. [GH-1920]
* agent: Defaults bind address to 127.0.0.1 when running in `-dev` mode. [GH-1878]
* agent: Added version information to the log when Consul starts up. [GH-1404]
* agent: Added timing metrics for HTTP requests in the form of `consul.http.<verb>.<path>`. [GH-2256]
* build: Updated all vendored dependencies. [GH-2258]
* build: Consul releases are now built with Go 1.6.3. [GH-2260]
* checks: Script checks now support an optional `timeout` parameter. [GH-1762]
* checks: HTTP health checks limit saved output to 4K to avoid performance issues. [GH-1952]
* cli: Added a `-stale` mode for watchers to allow them to pull data from any Consul server, not just the leader. [GH-2045] [GH-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]
* 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]
* 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]
* dns: Added a new `-dns-port` command line option so this can be set without a config file. [GH-2263]
* ui: Added a new network tomography visualization to the UI. [GH-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]
* agent: External services can now be registered with ACL tokens. [GH-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]
* agent: Gossip encryption keys are now validated before being made persistent in the keyring, avoiding delayed feedback at runtime. [GH-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]
* 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] [GH-2220]
* server: Fixed a deadlock related to sorting the list of available datacenters by round trip time. [GH-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]
* 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]
