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This rule can report problems related to jinja2 string templates. The current version can report:

  • jinja[spacing] when there are no spaces between variables and operators, including filters, like {{ var_name | filter }}. This improves readability and makes it less likely to introduce typos.
  • jinja[invalid] when the jinja2 template is invalid, like {{ {{ '1' }} }}, which would result in a runtime error if you try to use it with Ansible, even if it does pass the Ansible syntax check.

As jinja2 syntax is closely following Python one we aim to follow black formatting rules. If you are curious how black would reformat a small snippet feel free to visit online black formatter site. Keep in mind to not include the entire jinja2 template, so instead of {{ 1+2==3 }}, do paste only 1+2==3.

In ansible, changed_when, failed_when, until, when are considered to use implicit jinja2 templating, meaning that they do not require {{ }}. Our rule will suggest the removal of the braces for these fields.

Problematic code

- name: Some task
    foo: "{{some|dict2items}}" # <-- jinja[spacing]
    bar: "{{ & }}" # <-- jinja[invalid]
  when: "{{ foo | bool }}" # <-- jinja[spacing] - 'when' has implicit templating

Correct code

- name: Some task
    foo: "{{ some | dict2items }}"
    bar: "{{ '&' }}"
  when: foo | bool

Current limitations

In its current form, this rule presents the following limitations:

  • Jinja2 blocks that have newlines in them will not be reformatted because we consider that the user deliberately wanted to format them in a particular way.
  • Jinja2 blocks that use tilde as a binary operation are ignored because black does not support tilde as a binary operator. Example: {{ a ~ b }}.
  • Jinja2 blocks that use dot notation with numbers are ignored because python and black do not allow it. Example: {{ }}


This rule can be automatically fixed using --fix option.