consul/api
R.B. Boyer 6adad71125
wan federation via mesh gateways (#6884)
This is like a Möbius strip of code due to the fact that low-level components (serf/memberlist) are connected to high-level components (the catalog and mesh-gateways) in a twisty maze of references which make it hard to dive into. With that in mind here's a high level summary of what you'll find in the patch:

There are several distinct chunks of code that are affected:

* new flags and config options for the server

* retry join WAN is slightly different

* retry join code is shared to discover primary mesh gateways from secondary datacenters

* because retry join logic runs in the *agent* and the results of that
  operation for primary mesh gateways are needed in the *server* there are
  some methods like `RefreshPrimaryGatewayFallbackAddresses` that must occur
  at multiple layers of abstraction just to pass the data down to the right
  layer.

* new cache type `FederationStateListMeshGatewaysName` for use in `proxycfg/xds` layers

* the function signature for RPC dialing picked up a new required field (the
  node name of the destination)

* several new RPCs for manipulating a FederationState object:
  `FederationState:{Apply,Get,List,ListMeshGateways}`

* 3 read-only internal APIs for debugging use to invoke those RPCs from curl

* raft and fsm changes to persist these FederationStates

* replication for FederationStates as they are canonically stored in the
  Primary and replicated to the Secondaries.

* a special derivative of anti-entropy that runs in secondaries to snapshot
  their local mesh gateway `CheckServiceNodes` and sync them into their upstream
  FederationState in the primary (this works in conjunction with the
  replication to distribute addresses for all mesh gateways in all DCs to all
  other DCs)

* a "gateway locator" convenience object to make use of this data to choose
  the addresses of gateways to use for any given RPC or gossip operation to a
  remote DC. This gets data from the "retry join" logic in the agent and also
  directly calls into the FSM.

* RPC (`:8300`) on the server sniffs the first byte of a new connection to
  determine if it's actually doing native TLS. If so it checks the ALPN header
  for protocol determination (just like how the existing system uses the
  type-byte marker).

* 2 new kinds of protocols are exclusively decoded via this native TLS
  mechanism: one for ferrying "packet" operations (udp-like) from the gossip
  layer and one for "stream" operations (tcp-like). The packet operations
  re-use sockets (using length-prefixing) to cut down on TLS re-negotiation
  overhead.

* the server instances specially wrap the `memberlist.NetTransport` when running
  with gateway federation enabled (in a `wanfed.Transport`). The general gist is
  that if it tries to dial a node in the SAME datacenter (deduced by looking
  at the suffix of the node name) there is no change. If dialing a DIFFERENT
  datacenter it is wrapped up in a TLS+ALPN blob and sent through some mesh
  gateways to eventually end up in a server's :8300 port.

* a new flag when launching a mesh gateway via `consul connect envoy` to
  indicate that the servers are to be exposed. This sets a special service
  meta when registering the gateway into the catalog.

* `proxycfg/xds` notice this metadata blob to activate additional watches for
  the FederationState objects as well as the location of all of the consul
  servers in that datacenter.

* `xds:` if the extra metadata is in place additional clusters are defined in a
  DC to bulk sink all traffic to another DC's gateways. For the current
  datacenter we listen on a wildcard name (`server.<dc>.consul`) that load
  balances all servers as well as one mini-cluster per node
  (`<node>.server.<dc>.consul`)

* the `consul tls cert create` command got a new flag (`-node`) to help create
  an additional SAN in certs that can be used with this flavor of federation.
2020-03-09 15:59:02 -05:00
..
watch Allow users to configure either unstructured or JSON logging (#7130) 2020-01-28 17:50:41 -06:00
README.md
acl.go Add Namespace support to the API module and the CLI commands (#6874) 2019-12-06 11:14:56 -05:00
acl_test.go
agent.go feat: support sending body in HTTP checks (#6602) 2020-02-10 09:27:12 -07:00
agent_test.go api: add replace-existing-checks param to the api package (#7136) 2020-02-03 10:11:40 +01:00
api.go Allow users to configure either unstructured or JSON logging (#7130) 2020-01-28 17:50:41 -06:00
api_test.go Allow users to configure either unstructured or JSON logging (#7130) 2020-01-28 17:50:41 -06:00
catalog.go Add the v1/catalog/node-services/:node endpoint (#7115) 2020-01-24 09:27:25 -05:00
catalog_test.go Add the v1/catalog/node-services/:node endpoint (#7115) 2020-01-24 09:27:25 -05:00
config_entry.go Updates to Config Entries and Connect for Namespaces (#7116) 2020-01-24 10:04:58 -05:00
config_entry_discoverychain.go Updates to Config Entries and Connect for Namespaces (#7116) 2020-01-24 10:04:58 -05:00
config_entry_discoverychain_test.go Updates to Config Entries and Connect for Namespaces (#7116) 2020-01-24 10:04:58 -05:00
config_entry_test.go Expose HTTP-based paths through Connect proxy (#6446) 2019-09-25 20:55:52 -06:00
connect.go
connect_ca.go connect: check if intermediate cert needs to be renewed. (#6835) 2020-01-17 23:27:13 +01:00
connect_ca_test.go connect: check if intermediate cert needs to be renewed. (#6835) 2020-01-17 23:27:13 +01:00
connect_intention.go
connect_intention_test.go
coordinate.go docs: Miscellaneous docs cleanup (#6742) 2019-11-05 20:34:46 -08:00
coordinate_test.go
debug.go
debug_test.go
discovery_chain.go Catalog + Namespace OSS changes. (#7219) 2020-02-10 10:40:44 -05:00
discovery_chain_test.go Fix TestAPI_DiscoveryChain_Get flake (#7082) 2020-01-20 14:56:56 +00:00
event.go
event_test.go
go.mod wan federation via mesh gateways (#6884) 2020-03-09 15:59:02 -05:00
go.sum wan federation via mesh gateways (#6884) 2020-03-09 15:59:02 -05:00
health.go feat: support sending body in HTTP checks (#6602) 2020-02-10 09:27:12 -07:00
health_test.go Sync of OSS changes to support namespaces (#6909) 2019-12-09 21:26:41 -05:00
kv.go build: fix makefile and CI 'fmt' and 'vet' tasks (#6937) 2019-12-11 12:32:11 -06:00
kv_test.go Sync of OSS changes to support namespaces (#6909) 2019-12-09 21:26:41 -05:00
lock.go Sync of OSS changes to support namespaces (#6909) 2019-12-09 21:26:41 -05:00
lock_test.go
namespace.go Add kv meta to namespaces api module (#6958) 2019-12-17 10:28:51 -07:00
namespace_test.go Add kv meta to namespaces api module (#6958) 2019-12-17 10:28:51 -07:00
operator.go
operator_area.go
operator_autopilot.go Use encoding/json as JSON decoder instead of mapstructure (#6680) 2019-10-29 11:13:36 -07:00
operator_autopilot_test.go
operator_keyring.go
operator_keyring_test.go
operator_license.go
operator_raft.go
operator_raft_test.go
operator_segment.go
oss_test.go Sync of OSS changes to support namespaces (#6909) 2019-12-09 21:26:41 -05:00
prepared_query.go Catalog + Namespace OSS changes. (#7219) 2020-02-10 10:40:44 -05:00
prepared_query_test.go
raw.go
semaphore.go Sync of OSS changes to support namespaces (#6909) 2019-12-09 21:26:41 -05:00
semaphore_test.go Sync of OSS changes to support namespaces (#6909) 2019-12-09 21:26:41 -05:00
session.go build: fix makefile and CI 'fmt' and 'vet' tasks (#6937) 2019-12-11 12:32:11 -06:00
session_test.go Sync of OSS changes to support namespaces (#6909) 2019-12-09 21:26:41 -05:00
snapshot.go
snapshot_test.go
status.go
status_test.go
txn.go Updates to the Txn API for namespaces (#7172) 2020-01-30 13:12:26 -05:00
txn_test.go Add support for dual stack IPv4/IPv6 network (#6640) 2020-01-17 09:54:17 -05:00

README.md

Consul API client

This package provides the api package which attempts to provide programmatic access to the full Consul API.

Currently, all of the Consul APIs included in version 0.6.0 are supported.

Documentation

The full documentation is available on Godoc

Usage

Below is an example of using the Consul client:

package main

import "github.com/hashicorp/consul/api"
import "fmt"

func main() {
	// Get a new client
	client, err := api.NewClient(api.DefaultConfig())
	if err != nil {
		panic(err)
	}

	// Get a handle to the KV API
	kv := client.KV()

	// PUT a new KV pair
	p := &api.KVPair{Key: "REDIS_MAXCLIENTS", Value: []byte("1000")}
	_, err = kv.Put(p, nil)
	if err != nil {
		panic(err)
	}

	// Lookup the pair
	pair, _, err := kv.Get("REDIS_MAXCLIENTS", nil)
	if err != nil {
		panic(err)
	}
	fmt.Printf("KV: %v %s\n", pair.Key, pair.Value)
}

To run this example, start a Consul server:

consul agent -dev

Copy the code above into a file such as main.go.

Install and run. You'll see a key (REDIS_MAXCLIENTS) and value (1000) printed.

$ go get
$ go run main.go
KV: REDIS_MAXCLIENTS 1000

After running the code, you can also view the values in the Consul UI on your local machine at http://localhost:8500/ui/dc1/kv