OpenSearch/docs/reference/cluster/tasks.asciidoc
Nik Everett 4b1c116461 Generate and run tests from the docs
Adds infrastructure so `gradle :docs:check` will extract tests from
snippets in the documentation and execute the tests. This is included
in `gradle check` so it should happen on CI and during a normal build.

By default each `// AUTOSENSE` snippet creates a unique REST test. These
tests are executed in a random order and the cluster is wiped between
each one. If multiple snippets chain together into a test you can annotate
all snippets after the first with `// TEST[continued]` to have the
generated tests for both snippets joined.

Snippets marked as `// TESTRESPONSE` are checked against the response
of the last action.

See docs/README.asciidoc for lots more.

Closes #12583. That issue is about catching bugs in the docs during build.
This catches *some* bugs in the docs during build which is a good start.
2016-05-05 13:58:03 -04:00

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[[tasks]]
== Task Management API
experimental[The Task Management API is new and should still be considered experimental. The API may change in ways that are not backwards compatible]
[float]
=== Current Tasks Information
The task management API allows to retrieve information about the tasks currently
executing on one or more nodes in the cluster.
[source,js]
--------------------------------------------------
GET _tasks <1>
GET _tasks?nodes=nodeId1,nodeId2 <2>
GET _tasks?nodes=nodeId1,nodeId2&actions=cluster:* <3>
--------------------------------------------------
// AUTOSENSE
<1> Retrieves all tasks currently running on all nodes in the cluster.
<2> Retrieves all tasks running on nodes `nodeId1` and `nodeId2`. See <<cluster-nodes>> for more info about how to select individual nodes.
<3> Retrieves all cluster-related tasks running on nodes `nodeId1` and `nodeId2`.
The result will look similar to the following:
[source,js]
--------------------------------------------------
{
"nodes" : {
"oTUltX4IQMOUUVeiohTt8A" : {
"name" : "Tamara Rahn",
"transport_address" : "127.0.0.1:9300",
"host" : "127.0.0.1",
"ip" : "127.0.0.1:9300",
"tasks" : {
"oTUltX4IQMOUUVeiohTt8A:124" : {
"node" : "oTUltX4IQMOUUVeiohTt8A",
"id" : 124,
"type" : "direct",
"action" : "cluster:monitor/tasks/lists[n]",
"start_time_in_millis" : 1458585884904,
"running_time_in_nanos" : 47402,
"cancellable" : false,
"parent_task_id" : "oTUltX4IQMOUUVeiohTt8A:123"
},
"oTUltX4IQMOUUVeiohTt8A:123" : {
"node" : "oTUltX4IQMOUUVeiohTt8A",
"id" : 123,
"type" : "transport",
"action" : "cluster:monitor/tasks/lists",
"start_time_in_millis" : 1458585884904,
"running_time_in_nanos" : 236042,
"cancellable" : false
}
}
}
}
}
--------------------------------------------------
It is also possible to retrieve information for a particular task, or all children of a particular
tasks using the following two commands:
[source,js]
--------------------------------------------------
GET _tasks/taskId:1
GET _tasks?parent_task_id=parentTaskId:1
--------------------------------------------------
// AUTOSENSE
The task API can be also used to wait for completion of a particular task. The following call will
block for 10 seconds or until the task with id `oTUltX4IQMOUUVeiohTt8A:12345` is completed.
[source,js]
--------------------------------------------------
GET _tasks/oTUltX4IQMOUUVeiohTt8A:12345?wait_for_completion=true&timeout=10s
--------------------------------------------------
// AUTOSENSE
Tasks can be also listed using _cat version of the list tasks command, which accepts the same arguments
as the standard list tasks command.
[source,js]
--------------------------------------------------
GET _cat/tasks
--------------------------------------------------
// AUTOSENSE
[float]
=== Task Cancellation
If a long-running task supports cancellation, it can be cancelled by the following command:
[source,js]
--------------------------------------------------
POST _tasks/taskId:1/_cancel
--------------------------------------------------
// AUTOSENSE
The task cancellation command supports the same task selection parameters as the list tasks command, so multiple tasks
can be cancelled at the same time. For example, the following command will cancel all reindex tasks running on the
nodes `nodeId1` and `nodeId2`.
[source,js]
--------------------------------------------------
POST _tasks/_cancel?node_id=nodeId1,nodeId2&actions=*reindex
--------------------------------------------------
// AUTOSENSE
[float]
=== Task Grouping
The task lists returned by task API commands can be grouped either by nodes (default) or by parent tasks using the `group_by` parameter.
The following command will change the grouping to parent tasks:
[source,js]
--------------------------------------------------
GET _tasks?group_by=parents
--------------------------------------------------
// AUTOSENSE