truthy¶

What this rule does¶

Reports bareword string values that YAML 1.1 would interpret as booleans. By default only true and false are accepted; all other YAML 1.1 truthy words (yes, no, on, off, True, Yes, ...) are flagged.

Why this matters¶

Silent type coercion. A literal yes parses as the boolean true under YAML 1.1, which is rarely what an author intended for a country code, a country name, or a configuration value.
Cross-parser drift. Some libraries still default to YAML 1.1 semantics, others to 1.2; flagging the ambiguous words makes the document behave the same way everywhere.

Configuration¶

[rules.truthy]
level = "error"
allowed-values = ["true", "false"]
check-keys = true

Option	Default	Description
`allowed-values`	`["true", "false"]`	Bareword values that are permitted. Everything else triggers the rule.
`check-keys`	`true`	Also report truthy values used as mapping keys.

Examples¶

Allowed (defaults)¶

enabled: true
visible: false

Reported (defaults)¶

enabled: yes
flag: On
country: NO

Allowed (with `allowed-values: ["true", "false", "yes", "no"]`)¶

enabled: yes
visible: no

Automatic fixing¶

This rule does not auto-fix; replacing a bareword changes the value's type and meaning, which requires intent from the author.

quoted-strings — quoting a value disables type coercion so the literal stays a string.
empty-values — a related class of "what did the author actually mean" ambiguity.