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Clarifies how Ansible processes multiple failed_when conditions (#55941)

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Docs: Clarify that multiple failed_when conditions join with AND not OR to counter third-party pages online incorrectly stating that it uses `OR`. ([example](https://groups.google.com/d/msg/ansible-project/cIaQTmY3ZLE/c5w8rlmdHWIJ)).
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Alicia Cozine 2019-05-01 07:31:59 -05:00 committed by GitHub
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18
docs/docsite/rst/user_guide/playbooks_error_handling.rst
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@ -63,11 +63,9 @@ the handler from running, such as a host becoming unreachable.)
Controlling What Defines Failure
````````````````````````````````
Suppose the error code of a command is meaningless and to tell if there
is a failure what really matters is the output of the command, for instance
if the string "FAILED" is in the output.
Ansible lets you define what "failure" means in each task using the ``failed_when`` conditional. As with all conditionals in Ansible, lists of multiple ``failed_when`` conditions are joined with an implicit ``and``, meaning the task only fails when *all* conditions are met. If you want to trigger a failure when any of the conditions is met, you must define the conditions in a string with an explicit ``or`` operator.
Ansible provides a way to specify this behavior as follows::
You may check for failure by searching for a word or phrase in the output of a command::
- name: Fail task when the command error output prints FAILED
command: /usr/bin/example-command -x -y -z
@ -93,14 +91,18 @@ In previous version of Ansible, this can still be accomplished as follows::
msg: "the command failed"
when: "'FAILED' in command_result.stderr"
You can also combine multiple conditions to specify this behavior as follows::
You can also combine multiple conditions for failure. This task will fail if both conditions are true::
- name: Check if a file exists in temp and fail task if it does
command: ls /tmp/this_should_not_be_here
register: result
failed_when:
- '"No such" not in result.stdout'
- result.rc == 0
- '"No such" not in result.stdout'
If you want the task to fail when only one condition is satisfied, change the ``failed_when`` definition to::
failed_when: result.rc == 0 or "No such" not in result.stdout
.. _override_the_changed_result:
@ -168,7 +170,7 @@ Blocks only deal with 'failed' status of a task. A bad task definition or an unr
- debug:
msg: 'I caught an error, can do stuff here to fix it, :-)'
This will 'revert' the failed status of the outer ``block`` task for the run and the play will continue as if it had succeeded.
This will 'revert' the failed status of the outer ``block`` task for the run and the play will continue as if it had succeeded.
See :ref:`block_error_handling` for more examples.
.. seealso::
@ -185,5 +187,3 @@ See :ref:`block_error_handling` for more examples.
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`irc.freenode.net <http://irc.freenode.net>`_
#ansible IRC chat channel