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This rule checks YAML syntax by using yamllint but with few minor default configuration changes.


Auto-fix functionality will change inline comment indentation to one character instead of two, which is the default of yamllint. The reason for this decision is for keeping reformatting compatibility with prettier, which is the most popular reformatter.

    min-spaces-from-content: 1 # prettier compatibility

There is no need to create this yamllint config file, but if you also run yamllint yourself, you might want to create it to make it behave the same way as ansible-lint.

You can disable YAML syntax violations by adding yaml to the skip_list in your Ansible-lint configuration as follows:

  - yaml

For more fine-grained control, disable violations for specific rules using tag identifiers in the yaml[yamllint_rule] format as follows:

  - yaml[trailing-spaces]
  - yaml[indentation]

If you want Ansible-lint to report YAML syntax violations as warnings, and not fatal errors, add tag identifiers to the warn_list in your configuration, for example:

  - yaml[document-start]


You cannot use tags: [skip_ansible_lint] to disable this rule but you can use yamllint magic comments for tuning it.

See the list of yamllint rules for more information.

Some of the detailed error codes that you might see are:

  • yaml[brackets] - too few spaces inside empty brackets, or too many spaces inside brackets
  • yaml[colons] - too many spaces before colon, or too many spaces after colon
  • yaml[commas] - too many spaces before comma, or too few spaces after comma
  • yaml[comments-indentation] - Comment not indented like content
  • yaml[comments] - Too few spaces before comment, or Missing starting space in comment
  • yaml[document-start] - missing document start "---" or found forbidden document start "---"
  • yaml[empty-lines] - too many blank lines (...> ...)
  • yaml[indentation] - Wrong indentation: expected ... but found ...
  • yaml[key-duplicates] - Duplication of key "..." in mapping
  • yaml[line-length] - Line too long (... > ... characters)
  • yaml[new-line-at-end-of-file] - No new line character at the end of file
  • yaml[octal-values]: forbidden implicit or explicit octal value
  • yaml[syntax] - YAML syntax is broken
  • yaml[trailing-spaces] - Spaces are found at the end of lines
  • yaml[truthy] - Truthy value should be one of ...


As YAML specification regarding octal values changed at least 3 times in 1.1, 1.2.0 and 1.2.2 we now require users to always add quotes around octal values, so the YAML loaders will all load them as strings, providing a consistent behavior. This is also safer as JSON does not support octal values either.

By default, yamllint does not check for octals but our custom default ruleset for it does check these. If for some reason, you do not want to follow our defaults, you can create a .yamllint file in your project and this will take precedence over our defaults.

Additional Information for Multiline Strings

Adhering to yaml[line-length] rule, for writing multiline strings we recommend using Block Style Indicator: literal style indicated by a pipe (|) or folded style indicated by a right angle bracket (>), instead of escaping the newlines with backslashes. Reference guide for writing multiple line strings in yaml.

Problematic code

# Missing YAML document start.
foo: 0777 # <-- yaml[octal-values]
foo2: 0o777 # <-- yaml[octal-values]
foo2: ... # <-- yaml[key-duplicates]
bar: ...       # <-- yaml[comments-indentation]

Correct code

foo: "0777" # <-- Explicitly quoting octal is less risky.
foo2: "0o777" # <-- Explicitly quoting octal is less risky.
bar: ... # Correct comment indentation.