open-consul/website/source/docs/agent/http/session.html.markdown

---
layout: "docs"
page_title: "Sessions (HTTP)"
sidebar_current: "docs-agent-http-sessions"
description: >
  The Session endpoints are used to create, destroy, and query sessions.
---

# Session HTTP Endpoint

The Session endpoints are used to create, destroy, and query sessions.
The following endpoints are supported:

* [`/v1/session/create`](#session_create): Creates a new session
* [`/v1/session/destroy/<session>`](#session_destroy): Destroys a given session
* [`/v1/session/info/<session>`](#session_info): Queries a given session
* [`/v1/session/node/<node>`](#session_node): Lists sessions belonging to a node
* [`/v1/session/list`](#session_list): Lists all active sessions
* [`/v1/session/renew`](#session_renew): Renews a TTL-based session

All of the read session endpoints support blocking queries and all consistency modes.

### <a name="session_create"></a> /v1/session/create

The create endpoint is used to initialize a new session.
There is more documentation on sessions [here](/docs/internals/sessions.html).
Sessions must be associated with a node and may be associated with any number of checks.

The create endpoint expects a JSON request body to be PUT. The request
body must look like:

```javascript
{
  "LockDelay": "15s",
  "Name": "my-service-lock",
  "Node": "foobar",
  "Checks": ["a", "b", "c"],
  "Behavior": "release",
  "TTL": "0s"
}
```

None of the fields are mandatory, and in fact no body needs to be PUT
if the defaults are to be used.

By default, the agent's local datacenter is used; another datacenter
can be specified using the "?dc=" query parameter. However, it is not recommended
to use cross-datacenter sessions.

`LockDelay` field can be specified as a duration string using a "s" suffix for
seconds. The default is 15s. This value can also be a numeric value. Small values are
treated as seconds while larger values are assumed to be nanoseconds.
<QUESTION: I don't see anywhere in the code to substantiate this.  If this is true, how do we define small and large values? We need to give people some boundaries.  QUESTION>

`Node` must refer to a node that is already registered, if specified. By default,
the agent's own node name is used.

`Name` can be used to provide a human-readable name for the Session.

`Checks` is used to provide a list of associated health checks. It is highly recommended
that, if you override this list, you include the default "serfHealthCheck".

`Behavior` can be set to either `release` or `delete`. This controls
the behavior when a session is invalidated. By default, this is `release`, 
causing any locks that are held to be released. Changing this to `delete`
causes any locks that are held to be deleted. `delete is useful for creating ephemeral
key/value entries.

The `TTL` field is a duration string, and like `LockDelay` it can use "s" as
a suffix for seconds. If specified, it must be between 10s and 3600s currently.
When provided, the session is invalidated if it is not renewed before the TTL
expires. See the [session internals page](/docs/internals/session.html) for more
documentation of this feature.

The return code is 200 on success and returns the ID of the created session:

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

### <a name="session_destroy"></a> /v1/session/destroy/\<session\>

The destroy endpoint is hit with a PUT and destroys the given session.
By default, the local datacenter is used, but the "?dc=" query parameter
can be used to specify the datacenter.

The session being destroyed must be provided on the path.

The return code is 200 on success.

### <a name="session_info"></a> /v1/session/info/\<session\>

This endpoint is hit with a GET and returns the requested session information
within a given datacenter. By default, the datacenter of the agent is queried;
however, the dc can be provided using the "?dc=" query parameter.
The session being queried must be provided on the path.

It returns a JSON body like this:

```javascript
[
  {
    "LockDelay": 1.5e+10,
    "Checks": [
      "serfHealth"
    ],
    "Node": "foobar",
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "CreateIndex": 1086449
  }
]
```

If the session is not found, null is returned instead of a JSON list.
This endpoint supports blocking queries and all consistency modes.

### <a name="session_node"></a> /v1/session/node/\<node\>

This endpoint is hit with a GET and returns the active sessions
for a given node and datacenter. By default, the datacenter of the agent is queried;
however, the dc can be provided using the "?dc=" query parameter.

The node being queried must be provided on the path.

It returns a JSON body like this:

```javascript
[
  {
    "LockDelay": 1.5e+10,
    "Checks": [
      "serfHealth"
    ],
    "Node": "foobar",
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "CreateIndex": 1086449
  },
  ...
]
```

This endpoint supports blocking queries and all consistency modes.

### <a name="session_list"></a> /v1/session/list

This endpoint is hit with a GET and returns the active sessions
for a given datacenter. By default, the datacenter of the agent is queried;
however, the dc can be provided using the "?dc=" query parameter.

It returns a JSON body like this:

```javascript
[
  {
    "LockDelay": 1.5e+10,
    "Checks": [
      "serfHealth"
    ],
    "Node": "foobar",
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "CreateIndex": 1086449
  },
  ...
]
```

This endpoint supports blocking queries and all consistency modes.

### <a name="session_renew"></a> /v1/session/renew/\<session\>

The renew endpoint is hit with a PUT and renews the given session.
This is used with sessions that have a TTL, and it extends the
expiration by the TTL. By default, the local datacenter is used, but the "?dc="
query parameter can be used to specify the datacenter.

The session being renewed must be provided on the path.

The return code is 200 on success and a JSON body like this:

```javascript
[
  {
    "LockDelay": 1.5e+10,
    "Checks": [
      "serfHealth"
    ],
    "Node": "foobar",
    "ID": "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
    "CreateIndex": 1086449
    "Behavior": "release",
    "TTL": "15s"
  }
]
```

The response body includes the current session.

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.