open-consul/website/source/api/session.html.md

layout	page_title	sidebar_current	description
api	Session - HTTP API	api-session	The /session endpoints create, destroy, and query sessions in Consul.

Session HTTP Endpoint

The /session endpoints create, destroy, and query sessions in Consul.

Create Session

This endpoint initializes a new session. Sessions must be associated with a node and may be associated with any number of checks.

Method	Path	Produces
PUT	/session/create	application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries	Consistency Modes	Agent Caching	ACL Required
NO	none	none	session:write

Parameters

• dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter. Using this across datacenters is not recommended.

• LockDelay (string: "15s") - Specifies the duration for the lock delay. This must be greater than 0.

• Node (string: "<agent>") - Specifies the name of the node. This must refer to a node that is already registered.

• Name (string: "") - Specifies a human-readable name for the session.

• Checks (array<string>: nil) - specifies a list of associated health check IDs (commonly CheckID in API responses). It is highly recommended that, if you override this list, you include the default serfHealth.

• Behavior (string: "release") - Controls the behavior to take when a session is invalidated. Valid values are:

  • release - causes any locks that are held to be released
  • delete - causes any locks that are held to be deleted

• TTL (string: "") - Specifies the number of seconds (between 10s and 86400s). If provided, the session is invalidated if it is not renewed before the TTL expires. The lowest practical TTL should be used to keep the number of managed sessions low. When locks are forcibly expired, such as when following the leader election pattern in an application, sessions may not be reaped for up to double this TTL, so long TTL values (> 1 hour) should be avoided.

Sample Payload

{
  "LockDelay": "15s",
  "Name": "my-service-lock",
  "Node": "foobar",
  "Checks": ["a", "b", "c"],
  "Behavior": "release",
  "TTL": "30s"
}

Sample Request

$ curl \
    --request PUT \
    --data @payload.json \
    http://127.0.0.1:8500/v1/session/create

Sample Response

{
  "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e"
}

• ID - the ID of the created session

Delete Session

This endpoint destroys the session with the given name. If the session UUID is malformed, an error is returned. If the session UUID does not exist or already expired, a 200 is still returned (the operation is idempotent).

Method	Path	Produces
PUT	/session/destroy/:uuid	application/json

Even though the Content-Type is application/json, the response is either a literal true or false, indicating of whether the destroy was successful.

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries	Consistency Modes	Agent Caching	ACL Required
NO	none	none	session:write

Parameters

• uuid (string: <required>) - Specifies the UUID of the session to destroy. This is required and is specified as part of the URL path.

• dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter. Using this across datacenters is not recommended.

Sample Request

$ curl \
    --request PUT
    http://127.0.0.1:8500/v1/session/destroy/adf4238a-882b-9ddc-4a9d-5b6758e4159e

Sample Response

true

Read Session

This endpoint returns the requested session information.

Method	Path	Produces
GET	/session/info/:uuid	application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries	Consistency Modes	Agent Caching	ACL Required
YES	all	none	session:read

Parameters

• uuid (string: <required>) - Specifies the UUID of the session to read. This is required and is specified as part of the URL path.

• dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter. Using this across datacenters is not recommended.

Sample Request

$ curl \
    http://127.0.0.1:8500/v1/session/info/adf4238a-882b-9ddc-4a9d-5b6758e4159e

Sample Response

[
  {
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "Name": "test-session",
    "Node": "raja-laptop-02",    
    "Checks": [
      "serfHealth"
    ],
    "LockDelay": 1.5e+10,
    "Behavior": "release",
    "TTL": "30s",
    "CreateIndex": 1086449,
    "ModifyIndex": 1086449
  }
]

If the session does not exist, null is returned instead of a JSON list.

List Sessions for Node

This endpoint returns the active sessions for a given node.

Method	Path	Produces
GET	/session/node/:node	application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries	Consistency Modes	Agent Caching	ACL Required
YES	all	none	session:read

Parameters

• node (string: <required>) - Specifies the name or ID of the node to query. This is required and is specified as part of the URL path.

• dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter. Using this across datacenters is not recommended.

Sample Request

$ curl \
    http://127.0.0.1:8500/v1/session/node/node-abcd1234

Sample Response

[
  {
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "Name": "test-session",
    "Node": "raja-laptop-02",    
    "Checks": [
      "serfHealth"
    ],
    "LockDelay": 1.5e+10,
    "Behavior": "release",
    "TTL": "30s",
    "CreateIndex": 1086449,
    "ModifyIndex": 1086449
  }
]

List Sessions

This endpoint returns the list of active sessions.

Method	Path	Produces
GET	/session/list	application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries	Consistency Modes	Agent Caching	ACL Required
YES	all	none	session:read

Parameters

• dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter. Using this across datacenters is not recommended.

Sample Request

$ curl \
    http://127.0.0.1:8500/v1/session/list

Sample Response

[
  {
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "Name": "test-session",
    "Node": "raja-laptop-02",    
    "Checks": [
      "serfHealth"
    ],
    "LockDelay": 1.5e+10,
    "Behavior": "release",
    "TTL": "30s",
    "CreateIndex": 1086449,
    "ModifyIndex": 1086449
  }
]

Renew Session

This endpoint renews the given session. This is used with sessions that have a TTL, and it extends the expiration by the TTL.

Method	Path	Produces
PUT	/session/renew/:uuid	application/json

The table below shows this endpoint's support for blocking queries, consistency modes, agent caching, and required ACLs.

Blocking Queries	Consistency Modes	Agent Caching	ACL Required
NO	none	none	session:write

Parameters

• uuid (string: <required>) - Specifies the UUID of the session to renew. This is required and is specified as part of the URL path.

• dc (string: "") - Specifies the datacenter to query. This will default to the datacenter of the agent being queried. This is specified as part of the URL as a query parameter. Using this across datacenters is not recommended.

Sample Request

$ curl \
    --request PUT \
    http://127.0.0.1:8500/v1/session/renew/adf4238a-882b-9ddc-4a9d-5b6758e4159e

Sample Response

[
  {
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "Name": "test-session",
    "Node": "raja-laptop-02",    
    "Checks": [
      "serfHealth"
    ],
    "LockDelay": 1.5e+10,
    "Behavior": "release",
    "TTL": "15s",
    "CreateIndex": 1086449,
    "ModifyIndex": 1086449
  }
]

-> Note: Consul may return a TTL value higher than the one specified during session creation. This indicates the server is under high load and is requesting clients renew less often.