ci: Initial pass at linting YAML files (#979)

Co-authored-by: Cody J. Hanson <[email protected]>

.github/workflows/check-yaml-format.yml

@@ -0,0 +1,29 @@
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+    branches:
+    - main
+
+jobs:
+  lint:
+    name: Lint YAML files
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Get changed files in the docs folder
+      id: changed-files
+      uses: tj-actions/changed-files@v34
+      with:
+        files: |
+          _data/**/*.yml
+
+    - name: Install yamllint
+      if: steps.changed-files.outputs.any_changed == 'true'
+      run: pipx install yamllint
+
+    - name: Lint YAML files
+      if: steps.changed-files.outputs.any_changed == 'true'
+      run: yamllint ${{ steps.changed-files.outputs.all_changed_files }}

.pre-commit-config.yaml

@@ -0,0 +1,7 @@
+# Update the rev variable with the release version that you want, from the yamllint repo
+# You can pass your custom .yamllint with args attribute.
+repos:
+- repo: https://github.com/adrienverge/yamllint.git
+  rev: v1.28.0
+  hooks:
+  - id: yamllint

.prettierignore

@@ -5,4 +5,6 @@ src/.temp
 _data
 assets
 schemas
-singer
+singer
+.pre-commit-config.yaml
+.yamllint.yaml

.yamllint.yaml

@@ -0,0 +1,16 @@
+extends: default
+
+ignore: |
+  .pre-commit-config.yaml
+
+rules:
+  braces:
+    forbid: non-empty
+  document-start:
+    present: false  # Don't require `---` at the start of the file
+  indentation:
+    indent-sequences: false
+    spaces: 2
+  key-ordering: enable
+  line-length:
+    max: 160

CONTRIBUTING.md

@@ -35,6 +35,19 @@ yarn
 yarn add --global @gridsome/cli
 ```
 
+### Linters
+
+You can use `pre-commit` to run the linters before committing.
+
+```console
+pipx install pre-commit
+pre-commit install
+```
+
+This will run the linters on all files that are staged for commit. Included linters:
+
+- [yamlllint](https://yamllint.readthedocs.io/en/stable/)
+
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