colons¶

What this rule does¶

Controls the number of spaces around mapping colons (:).

Why this matters¶

Readability. Consistent spacing makes columnar layouts easier to scan, especially in configuration files with many short keys.
Avoids ambiguity. Stray spaces around the colon can hide subtle parsing bugs, particularly when keys contain values that look like flow-style content.

Configuration¶

[rules.colons]
level = "error"
max-spaces-before = 0
max-spaces-after = 1

Option	Default	Description
`max-spaces-before`	`0`	Maximum spaces between the key and the `:`. Use `-1` to disable.
`max-spaces-after`	`1`	Maximum spaces between the `:` and the value. Use `-1` to disable.

Examples¶

Allowed (defaults)¶

key: value
object:
  - a
  - b

Reported (defaults)¶

key : value
key:   value

Allowed (with `max-spaces-after: 2`)¶

first:  1
second: 2
third:  3

Alias mapping keys¶

A YAML anchor/alias name may legally contain :, so *anchor: welds into an alias to an anchor named anchor: (a parse error here, since no mapping colon remains). Using an alias as a mapping key therefore requires one separating space before the colon — *anchor : value. When exactly that one space is present the colon's spacing is not reported (the rule defers to the parser's view of the alias); more than one space before the colon is reported as usual.

base: &a name
*a : value     # allowed: the one required separating space is not reported

base: &a name
*a  : value    # reported (2:4): too many spaces before colon

Automatic fixing¶

This rule does not auto-fix; correct spacing manually.

commas — the analogous rule for flow collection commas.
hyphens — spacing for block sequence hyphens.