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When to use a pattern in Ansible playbook?
Patterns are highly flexible – you can exclude or require subsets of hosts, use wildcards or regular expressions, and more. Ansible executes on all inventory hosts included in the pattern. You use a pattern almost any time you execute an ad hoc command or a playbook.
Why does hosts : all not match localhost in Ansible?
Note that the implicit localhost does not match ‘all’ When you use hosts: all in your playbook, localhost is not matched. Change your playbook to hosts: localhost. Explicitly provide an inventory file that has localhost. You can find more information about inventory in the Ansible documentation.
What happens if a pattern does not match a hostname?
If your pattern includes an IP address or hostname that does not appear in your inventory, you will see an error like this: Your pattern must match your inventory syntax. If you define a host as an alias:
Do you have to use host1 in a pattern?
If your pattern includes an IP address or hostname that does not appear in your inventory, you will see an error like this: Your pattern must match your inventory syntax. If you define a host as an alias: you must use the alias in your pattern. In the example above, you must use host1 in your pattern.
How to limit the number of hosts in Ansible?
You can also limit the hosts you target on a particular run with the –limit flag: Finally, you can use –limit to read the list of hosts from a file by prefixing the file name with @: If RETRY_FILES_ENABLED is set to True, a .retry file will be created after the ansible-playbook run containing a list of failed hosts from all plays.
What to do if your registered variable is empty in Ansible?
If you want to run another task only on hosts where the stdout of your registered variable is empty, check the registered variable’s string contents for emptiness: Ansible always registers something in a registered variable for every host, even on hosts where a task fails or Ansible skips a task because a condition is not met.
What is the correct tense for failure in Ansible?
Older versions of Ansible used success and fail, but succeeded and failed use the correct tense. All of these options are now valid. You can also create conditionals based on variables defined in the playbooks or inventory.