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open-consul/website/source/api/agent.html.md
Paul Banks 5b0d4db6bc Support Agent Caching for Service Discovery Results (#4541) 
* Add cache types for catalog/services and health/services and basic test that caching works

* Support non-blocking cache types with Cache-Control semantics.

* Update API docs to include caching info for every endpoint.

* Comment updates per PR feedback.

* Add note on caching to the 10,000 foot view on the architecture page to make the new data path more clear.

* Document prepared query staleness quirk and force all background requests to AllowStale so we can spread service discovery load across servers.
2018-10-10 16:55:34 +01:00

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---
layout: api
page_title: Agent - HTTP API
sidebar_current: api-agent
description: |-
The /agent endpoints interact with the local Consul agent to register
services, checks, list members, and more.
---
# Agent HTTP API
The `/agent` endpoints are used to interact with the local Consul agent.
Usually, services and checks are registered with an agent which then takes on
the burden of keeping that data synchronized with the cluster. For example, the
agent registers services and checks with the Catalog and performs
[anti-entropy](/docs/internals/anti-entropy.html) to recover from outages.
In addition to these endpoints, additional endpoints are grouped in the
navigation for `Checks` and `Services`.
## List Members
This endpoint returns the members the agent sees in the cluster gossip pool. Due
to the nature of gossip, this is eventually consistent: the results may differ
by agent. The strongly consistent view of nodes is instead provided by
`/v1/catalog/nodes`.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `GET` | `/agent/members` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------ |
| `NO` | `none` | `none` | `node:read` |
### Parameters
- `wan` `(bool: false)` - Specifies to list WAN members instead of the LAN
members (which is the default). This is only eligible for agents running in
**server mode**. This is specified as part of the URL as a query parameter.
- `segment` `(string: "")` - (Enterprise-only) Specifies the segment to list members for.
If left blank, this will query for the default segment when connecting to a server and
the agent's own segment when connecting to a client (clients can only be part of one
network segment). When querying a server, setting this to the special string `_all`
will show members in all segments.
### Sample Request
```text
$ curl \
http://127.0.0.1:8500/v1/agent/members
```
### Sample Response
```json
[
{
"Name": "foobar",
"Addr": "10.1.10.12",
"Port": 8301,
"Tags": {
"bootstrap": "1",
"dc": "dc1",
"port": "8300",
"role": "consul"
},
"Status": 1,
"ProtocolMin": 1,
"ProtocolMax": 2,
"ProtocolCur": 2,
"DelegateMin": 1,
"DelegateMax": 3,
"DelegateCur": 3
}
]
```
## Read Configuration
This endpoint returns the configuration and member information of the local
agent. The `Config` element contains a subset of the configuration and its
format will not change in a backwards incompatible way between releases.
`DebugConfig` contains the full runtime configuration but its format is subject
to change without notice or deprecation.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `GET` | `/agent/self` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------ |
| `NO` | `none` | `none` | `agent:read` |
### Sample Request
```text
$ curl \
http://127.0.0.1:8500/v1/agent/self
```
### Sample Response
```json
{
"Config": {
"Datacenter": "dc1",
"NodeName": "foobar",
"NodeID": "9d754d17-d864-b1d3-e758-f3fe25a9874f",
"Server": true,
"Revision": "deadbeef",
"Version": "1.0.0"
},
"DebugConfig": {
... full runtime configuration ...
... format subject to change ...
},
"Coord": {
"Adjustment": 0,
"Error": 1.5,
"Vec": [0,0,0,0,0,0,0,0]
},
"Member": {
"Name": "foobar",
"Addr": "10.1.10.12",
"Port": 8301,
"Tags": {
"bootstrap": "1",
"dc": "dc1",
"id": "40e4a748-2192-161a-0510-9bf59fe950b5",
"port": "8300",
"role": "consul",
"vsn": "1",
"vsn_max": "1",
"vsn_min": "1"
},
"Status": 1,
"ProtocolMin": 1,
"ProtocolMax": 2,
"ProtocolCur": 2,
"DelegateMin": 2,
"DelegateMax": 4,
"DelegateCur": 4
},
"Meta": {
"instance_type": "i2.xlarge",
"os_version": "ubuntu_16.04"
}
}
```
## Reload Agent
This endpoint instructs the agent to reload its configuration. Any errors
encountered during this process are returned.
Not all configuration options are reloadable. See the
[Reloadable Configuration](/docs/agent/options.html#reloadable-configuration)
section on the agent options page for details on which options are supported.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `PUT` | `/agent/reload` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------- |
| `NO` | `none` | `none` | `agent:write` |
### Sample Request
```text
$ curl \
--request PUT \
http://127.0.0.1:8500/v1/agent/reload
```
## Enable Maintenance Mode
This endpoint places the agent into "maintenance mode". During maintenance mode,
the node will be marked as unavailable and will not be present in DNS or API
queries. This API call is idempotent.
Maintenance mode is persistent and will be automatically restored on agent
restart.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `PUT` | `/agent/maintenance` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------ |
| `NO` | `none` | `none` | `node:write` |
### Parameters
- `enable` `(bool: <required>)` - Specifies whether to enable or disable
maintenance mode. This is specified as part of the URL as a query string
parameter.
- `reason` `(string: "")` - Specifies a text string explaining the reason for
placing the node into maintenance mode. This is simply to aid human operators.
If no reason is provided, a default value will be used instead. This is
specified as part of the URL as a query string parameter, and, as such, must
be URI-encoded.
### Sample Request
```text
$ curl \
--request PUT \
http://127.0.0.1:8500/v1/agent/maintenance?enable=true&reason=For+API+docs
```
## View Metrics
This endpoint will dump the metrics for the most recent finished interval.
For more information about metrics, see the [telemetry](/docs/agent/telemetry.html)
page.
In order to enable [Prometheus](https://prometheus.io/) support, you need to use the
configuration directive
[`prometheus_retention_time`](/docs/agent/options.html#telemetry-prometheus_retention_time).
| Method | Path | Produces |
| ------ | ---------------------------------- | ------------------------------------------ |
| `GET` | `/agent/metrics` | `application/json` |
| `GET` | `/agent/metrics?format=prometheus` | `text/plain; version=0.0.4; charset=utf-8` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------ |
| `NO` | `none` | `none` | `agent:read` |
### Sample Request
```text
$ curl \
http://127.0.0.1:8500/v1/agent/metrics
```
### Sample Response
```json
{
"Timestamp": "2017-08-08 02:55:10 +0000 UTC",
"Gauges": [
{
"Name": "consul.consul.session_ttl.active",
"Value": 0,
"Labels": {}
},
{
"Name": "consul.runtime.alloc_bytes",
"Value": 4704344,
"Labels": {}
},
{
"Name": "consul.runtime.free_count",
"Value": 74063,
"Labels": {}
}
],
"Points": [],
"Counters": [
{
"Name": "consul.consul.catalog.service.query",
"Count": 1,
"Sum": 1,
"Min": 1,
"Max": 1,
"Mean": 1,
"Stddev": 0,
"Labels": {
"service": "consul"
}
},
{
"Name": "consul.raft.apply",
"Count": 1,
"Sum": 1,
"Min": 1,
"Max": 1,
"Mean": 1,
"Stddev": 0,
"Labels": {}
}
],
"Samples": [
{
"Name": "consul.consul.http.GET.v1.agent.metrics",
"Count": 1,
"Sum": 0.1817069947719574,
"Min": 0.1817069947719574,
"Max": 0.1817069947719574,
"Mean": 0.1817069947719574,
"Stddev": 0,
"Labels": {}
},
{
"Name": "consul.consul.http.GET.v1.catalog.service._",
"Count": 1,
"Sum": 0.23342099785804749,
"Min": 0.23342099785804749,
"Max": 0.23342099785804749,
"Mean": 0.23342099785804749,
"Stddev": 0,
"Labels": {}
},
{
"Name": "consul.serf.queue.Query",
"Count": 20,
"Sum": 0,
"Min": 0,
"Max": 0,
"Mean": 0,
"Stddev": 0,
"Labels": {}
}
]
}
```
- `Timestamp` is the timestamp of the interval for the displayed metrics. Metrics are
aggregated on a ten second interval, so this value (along with the displayed metrics)
will change every ten seconds.
- `Gauges` is a list of gauges which store one value that is updated as time goes on,
such as the amount of memory allocated.
- `Points` is a list of point metrics, which each store a series of points under a given name.
- `Counters` is a list of counters, which store info about a metric that is incremented
over time such as the number of requests to an HTTP endpoint.
- `Samples` is a list of samples, which store info about the amount of time spent on an
operation, such as the time taken to serve a request to a specific http endpoint.
## Stream Logs
This endpoint streams logs from the local agent until the connection is closed.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `GET` | `/agent/monitor` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------ |
| `NO` | `none` | `none` | `agent:read` |
### Parameters
- `loglevel` `(string: "info")` - Specifies a text string containing a log level
to filter on, such as `info`.
### Sample Request
```text
$ curl \
http://127.0.0.1:8500/v1/agent/monitor
```
### Sample Response
```text
YYYY/MM/DD HH:MM:SS [INFO] raft: Initial configuration (index=1): [{Suffrage:Voter ID:127.0.0.1:8300 Address:127.0.0.1:8300}]
YYYY/MM/DD HH:MM:SS [INFO] raft: Node at 127.0.0.1:8300 [Follower] entering Follower state (Leader: "")
YYYY/MM/DD HH:MM:SS [INFO] serf: EventMemberJoin: machine-osx 127.0.0.1
YYYY/MM/DD HH:MM:SS [INFO] consul: Adding LAN server machine-osx (Addr: tcp/127.0.0.1:8300) (DC: dc1)
YYYY/MM/DD HH:MM:SS [INFO] serf: EventMemberJoin: machine-osx.dc1 127.0.0.1
YYYY/MM/DD HH:MM:SS [INFO] consul: Handled member-join event for server "machine-osx.dc1" in area "wan"
# ...
```
## Join Agent
This endpoint instructs the agent to attempt to connect to a given address.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `PUT` | `/agent/join/:address` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------- |
| `NO` | `none` | `none` | `agent:write` |
### Parameters
- `address` `(string: <required>)` - Specifies the address of the other agent to
join. This is specified as part of the URL.
- `wan` `(bool: false)` - Specifies to try and join over the WAN pool. This is
only optional for agents running in server mode. This is specified as part of
the URL as a query parameter
### Sample Request
```text
$ curl \
http://127.0.0.1:8500/v1/agent/join/1.2.3.4
```
## Graceful Leave and Shutdown
This endpoint triggers a graceful leave and shutdown of the agent. It is used to
ensure other nodes see the agent as "left" instead of "failed". Nodes that leave
will not attempt to re-join the cluster on restarting with a snapshot.
For nodes in server mode, the node is removed from the Raft peer set in a
graceful manner. This is critical, as in certain situations a non-graceful leave
can affect cluster availability.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `PUT` | `/agent/leave` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------- |
| `NO` | `none` | `none` | `agent:write` |
### Sample Request
```text
$ curl \
--request PUT \
http://127.0.0.1:8500/v1/agent/leave
```
## Force Leave and Shutdown
This endpoint instructs the agent to force a node into the `left` state. If a
node fails unexpectedly, then it will be in a `failed` state. Once in the
`failed` state, Consul will attempt to reconnect, and the services and checks
belonging to that node will not be cleaned up. Forcing a node into the `left`
state allows its old entries to be removed.
| Method | Path | Produces |
| ------ | ---------------------------- | -------------------------- |
| `PUT` | `/agent/force-leave` | `application/json` |
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------- |
| `NO` | `none` | `none` | `agent:write` |
### Sample Request
```text
$ curl \
--request PUT \
http://127.0.0.1:8500/v1/agent/force-leave
```
## Update ACL Tokens
This endpoint updates the ACL tokens currently in use by the agent. It can be
used to introduce ACL tokens to the agent for the first time, or to update
tokens that were initially loaded from the agent's configuration. Tokens are
not persisted, so will need to be updated again if the agent is restarted.
| Method | Path | Produces |
| ------ | ------------------------------------- | -------------------------- |
| `PUT` | `/agent/token/acl_token` | `application/json` |
| `PUT` | `/agent/token/acl_agent_token` | `application/json` |
| `PUT` | `/agent/token/acl_agent_master_token` | `application/json` |
| `PUT` | `/agent/token/acl_replication_token` | `application/json` |
The paths above correspond to the token names as found in the agent configuration:
[`acl_token`](/docs/agent/options.html#acl_token), [`acl_agent_token`](/docs/agent/options.html#acl_agent_token),
[`acl_agent_master_token`](/docs/agent/options.html#acl_agent_master_token), and
[`acl_replication_token`](/docs/agent/options.html#acl_replication_token).
The table below shows this endpoint's support for
[blocking queries](/api/index.html#blocking-queries),
[consistency modes](/api/index.html#consistency-modes),
[agent caching](/api/index.html#agent-caching), and
[required ACLs](/api/index.html#acls).
| Blocking Queries | Consistency Modes | Agent Caching | ACL Required |
| ---------------- | ----------------- | ------------- | ------------- |
| `NO` | `none` | `none` | `agent:write` |
### Parameters
- `Token` `(string: "")` - Specifies the ACL token to set.
### Sample Payload
```json
{
"Token": "adf4238a-882b-9ddc-4a9d-5b6758e4159e"
}
```
### Sample Request
```text
$ curl \
--request PUT \
--data @payload.json \
http://127.0.0.1:8500/v1/agent/token/acl_token
```
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