mirror of
https://github.com/ansible-collections/community.general.git
synced 2024-09-14 20:13:21 +02:00
157 lines
5 KiB
ReStructuredText
157 lines
5 KiB
ReStructuredText
.. _playbooks_async:
|
|
|
|
Asynchronous Actions and Polling
|
|
================================
|
|
|
|
By default tasks in playbooks block, meaning the connections stay open
|
|
until the task is done on each node. This may not always be desirable, or you may
|
|
be running operations that take longer than the SSH timeout.
|
|
|
|
To avoid blocking or timeout issues, you can use asynchronous mode to run all of your tasks at once and then poll until they are done.
|
|
|
|
The behaviour of asynchronous mode depends on the value of `poll`.
|
|
|
|
|
|
Avoid connection timeouts: poll > 0
|
|
-----------------------------------
|
|
|
|
When ``poll`` is a positive value, the playbook will *still* block on the task until it either completes, fails or times out.
|
|
|
|
In this case, however, `async` explicitly sets the timeout you wish to apply to this task rather than being limited by the connection method timeout.
|
|
|
|
To launch a task asynchronously, specify its maximum runtime
|
|
and how frequently you would like to poll for status. The default
|
|
poll value is set by the ``DEFAULT_POLL_INTERVAL`` setting if you do not specify a value for `poll`::
|
|
|
|
---
|
|
|
|
- hosts: all
|
|
remote_user: root
|
|
|
|
tasks:
|
|
|
|
- name: simulate long running op (15 sec), wait for up to 45 sec, poll every 5 sec
|
|
command: /bin/sleep 15
|
|
async: 45
|
|
poll: 5
|
|
|
|
.. note::
|
|
There is no default for the async time limit. If you leave off the
|
|
'async' keyword, the task runs synchronously, which is Ansible's
|
|
default.
|
|
|
|
.. note::
|
|
As of Ansible 2.3, async does not support check mode and will fail the
|
|
task when run in check mode. See :doc:`playbooks_checkmode` on how to
|
|
skip a task in check mode.
|
|
|
|
|
|
Concurrent tasks: poll = 0
|
|
--------------------------
|
|
|
|
When ``poll`` is 0, Ansible will start the task and immediately move on to the next one without waiting for a result.
|
|
|
|
From the point of view of sequencing this is asynchronous programming: tasks may now run concurrently.
|
|
|
|
The playbook run will end without checking back on async tasks.
|
|
|
|
The async tasks will run until they either complete, fail or timeout according to their `async` value.
|
|
|
|
If you need a synchronization point with a task, register it to obtain its job ID and use the :ref:`async_status <async_status_module>` module to observe it.
|
|
|
|
You may run a task asynchronously by specifying a poll value of 0::
|
|
|
|
---
|
|
|
|
- hosts: all
|
|
remote_user: root
|
|
|
|
tasks:
|
|
|
|
- name: simulate long running op, allow to run for 45 sec, fire and forget
|
|
command: /bin/sleep 15
|
|
async: 45
|
|
poll: 0
|
|
|
|
.. note::
|
|
You shouldn't attempt run a task asynchronously by specifying a poll value of 0 with operations that require
|
|
exclusive locks (such as yum transactions) if you expect to run other
|
|
commands later in the playbook against those same resources.
|
|
|
|
.. note::
|
|
Using a higher value for ``--forks`` will result in kicking off asynchronous
|
|
tasks even faster. This also increases the efficiency of polling.
|
|
|
|
If you would like to perform a task asynchronously and check on it later you can perform a task similar to the
|
|
following::
|
|
|
|
---
|
|
# Requires ansible 1.8+
|
|
- name: 'YUM - async task'
|
|
yum:
|
|
name: docker-io
|
|
state: present
|
|
async: 1000
|
|
poll: 0
|
|
register: yum_sleeper
|
|
|
|
- name: 'YUM - check on async task'
|
|
async_status:
|
|
jid: "{{ yum_sleeper.ansible_job_id }}"
|
|
register: job_result
|
|
until: job_result.finished
|
|
retries: 30
|
|
|
|
.. note::
|
|
If the value of ``async:`` is not high enough, this will cause the
|
|
"check on it later" task to fail because the temporary status file that
|
|
the ``async_status:`` is looking for will not have been written or no longer exist
|
|
|
|
If you would like to run multiple asynchronous tasks while limiting the amount
|
|
of tasks running concurrently, you can do it this way::
|
|
|
|
#####################
|
|
# main.yml
|
|
#####################
|
|
- name: Run items asynchronously in batch of two items
|
|
vars:
|
|
sleep_durations:
|
|
- 1
|
|
- 2
|
|
- 3
|
|
- 4
|
|
- 5
|
|
durations: "{{ item }}"
|
|
include_tasks: execute_batch.yml
|
|
loop: "{{ sleep_durations | batch(2) | list }}"
|
|
|
|
#####################
|
|
# execute_batch.yml
|
|
#####################
|
|
- name: Async sleeping for batched_items
|
|
command: sleep {{ async_item }}
|
|
async: 45
|
|
poll: 0
|
|
loop: "{{ durations }}"
|
|
loop_control:
|
|
loop_var: "async_item"
|
|
register: async_results
|
|
|
|
- name: Check sync status
|
|
async_status:
|
|
jid: "{{ async_result_item.ansible_job_id }}"
|
|
loop: "{{ async_results.results }}"
|
|
loop_control:
|
|
loop_var: "async_result_item"
|
|
register: async_poll_results
|
|
until: async_poll_results.finished
|
|
retries: 30
|
|
|
|
.. seealso::
|
|
|
|
:doc:`playbooks`
|
|
An introduction to playbooks
|
|
`User Mailing List <https://groups.google.com/group/ansible-devel>`_
|
|
Have a question? Stop by the google group!
|
|
`irc.freenode.net <http://irc.freenode.net>`_
|
|
#ansible IRC chat channel
|