ansible/docsite/rst/playbooks_error_handling.rst

Error Handling In Playbooks

Ansible normally has defaults that make sure to check the return codes of commands and modules and it fails fast -- forcing an error to be dealt with unless you decide otherwise. y Sometimes a command that returns 0 isn't an error. Sometimes a command might not always need to report that it 'changed' the remote system. This section describes how to change the default behavior of Ansible for certain tasks so output and error handling behavior is as desired.

Ignoring Failed Commands

0.6

Generally playbooks will stop executing any more steps on a host that has a failure. Sometimes, though, you want to continue on. To do so, write a task that looks like this:

- name: this will not be counted as a failure
  command: /bin/false
  ignore_errors: yes

Controlling What Defines Failure

1.4

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 in 1.4 and later provides a way to specify this behavior as follows:

- name: this command prints FAILED when it fails
  command: /usr/bin/example-command -x -y -z
  register: command_result
  failed_when: "'FAILED' in command_result.stderr"

In previous version of Ansible, this can be still be accomplished as follows:

- name: this command prints FAILED when it fails
  command: /usr/bin/example-command -x -y -z
  register: command_result
  ignore_errors: True

- name: fail the play if the previous command did not succeed
  fail: msg="the command failed"
  when: "'FAILED' in command_result.stderr"

Overriding The Changed Result

1.3

When a shell/command or other module runs it will typically report "changed" status based on whether it thinks it affected machine state.

Sometimes you will know, based on the return code or output that it did not make any changes, and wish to override the "changed" result such that it does not appear in report output or does not cause handlers to fire:

tasks:

  - shell: /usr/bin/billybass --mode="take me to the river"
    register: bass_result
    changed_when: "bass_result.rc != 2"

  # this will never report 'changed' status
  - shell: wall 'beep'
    changed_when: False

playbooks

An introduction to playbooks

playbooks_best_practices

Best practices in playbooks

playbooks_conditionals

Conditional statements in playbooks

playbooks_variables

All about variables

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