YAML Plugin

Rules for linting .yaml/.yml files containing arbitrary data in the Yet Another Markup Language (YAML) format.
This plugin comes packaged with the flint npm package.

Presets

Flint’s YAML plugin provides the following presets:

Preset	Recommended	Description
logical	✅ Always	Common rules for finding bugs and enforcing good logical practices in YAML files.
logicalStrict	☑️ When Ready	Additional rules for finding bugs and enforcing good logical practices in YAML files.
stylistic	✅ Always	Common rules for consistent styling and best stylistic practices in YAML files.
stylisticStrict	☑️ When Ready	Additional rules for consistent styling and best stylistic practices in YAML files.

If you are just getting started with linting, Flint recommends using the logical and stylistic presets:

flint.config.ts

import { defineConfig, yaml } from "flint";

export default defineConfig({
  use: [
    {
      files: yaml.files.all,
      rules: [yaml.presets.logical, yaml.presets.stylistic],
    },
  ],
});

If you are experienced with both YAML and linting, Flint recommends using the logicalStrict and stylisticStrict presets:

flint.config.ts

import { defineConfig, yaml } from "flint";

export default defineConfig({
  use: [
    {
      files: yaml.files.all,
      rules: [yaml.presets.logicalStrict, yaml.presets.stylisticStrict],
    },
  ],
});

Note

Coming soon: more expansive documentation on choosing and combining plugins & presets with Flint.

logical

Rules that find bugs and enforce good YAML practices for most-to-all YAML files.

flint.config.ts

import { defineConfig, yaml } from "flint";

export default defineConfig({
  use: [
    {
      files: yaml.files.all,
      rules: yaml.presets.logical,
    },
  ],
});

logicalStrict

Additional logical rules that enforce best practices which are not always straightforward to implement. These rules are recommended for projects where a majority of developers are experienced with both YAML and using a linter.

flint.config.ts

import { defineConfig, yaml } from "flint";

export default defineConfig({
  use: [
    {
      files: yaml.files.all,
      rules: yaml.presets.logicalStrict,
    },
  ],
});

This preset’s rules are a superset of those in logical.

stylistic

Rules that enforce consistent styling and best stylistic practices for most-to-all YAML files.

flint.config.ts

import { defineConfig, yaml } from "flint";

export default defineConfig({
  use: [
    {
      files: yaml.files.all,
      rules: yaml.presets.stylistic,
    },
  ],
});

stylisticStrict

Additional stylistic rules that enforce best practices which are not always straightforward to implement. These rules are recommended for projects where a majority of developers are experienced with both YAML and using a linter.

flint.config.ts

import { defineConfig, yaml } from "flint";

export default defineConfig({
  use: [
    {
      files: yaml.files.all,
      rules: yaml.presets.stylisticStrict,
    },
  ],
});

This preset’s rules are a superset of those in stylistic.

Rules

Implemented: 9 of 11 (81.8%)

Flint Rule	Preset
emptyDocumentsReports empty YAML documents that contain only document markers.	logical
emptyMappingKeysReports empty mapping keys.	logical
emptyMappingValuesReports empty mapping values.	logical
emptySequenceEntriesReports empty sequence entries.	logical
stringMappingKeysEnforces mapping keys to be strings.	logical (strict)
blockMappingsPrefer block-style mappings over flow-style mappings.	stylistic
blockSequencesPrefer block style sequences over flow style sequences.	stylistic
irregularWhitespace	stylistic
fileExtensions	stylistic (strict)
numericTrailingZerosReports trailing zeros in numeric values.	stylistic (strict)
plainScalarsPrefer plain style scalars over quoted scalars.	stylistic (strict)

Selectors

Flint’s YAML plugin provides the following file selector:

• all: **/*.{yaml,yml}