Separate GitHub action file and workflow file

During GitHub Workflow action writing yaml file and usually we use run to run some action in same file as below

I have my own action lint the markdown files and using own config file for that; so there was no need to call uses from existing action so use run which works fine

First Version

name: markdown-lint
run-name: learning github action from workflow
on: [push]
jobs:
  markdown-lint:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Setup Node.js environment
        uses: actions/setup-node@v4
        with:
          node-version: "20"

      - name: Lint Markdown files
        run: |
          npx markdownlint-cli '**/*.md' \
          --config '.github/workflows/.markdownlint.json' \
          --ignore '.github/CONTRIBUTING.md' \
          --ignore '.github/CODE_OF_CONDUCT.md'\
          --ignore 'CHANGELOG.md'

adding .markdownlint.json file near this file

Final Version

We can also separate the action completely and call the file using uses in place of run

Action file

created separate actions folder inside .github folder and create a file name action.yml under one file which is called from file in workflows folder

name: md-lint
description: Run npx markdownlint-cli
runs:
  using: "composite"
  steps:
    - shell: bash
      run: |
        npx markdownlint-cli '**/*.md' \
        --config './.markdownlint.json' \
        --ignore '.github/CONTRIBUTING.md' \
        --ignore '.github/CODE_OF_CONDUCT.md'\
        --ignore 'CHANGELOG.md'

Notes

we can use \ writing a long command in multiline
filename must be action.yml ’ this is default file under a folder so no need to mention while calling
move ./.markdownlint.json inside md-lint folder

Workflow File

This is how it is called inside workflows

name: markdown-lint
run-name: learning github action from workflow
on:
  push:
    branches:
      - main
      - develop
jobs:
  markdown-lint:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Setup Node.js environment
        uses: actions/setup-node@v4
        with:
          node-version: "20"

      - name: Lint Markdown files
        uses: ./.github/actions/md-lint

References

Thanks to this Stack overflow Answer

separate actions and workflow file in GitHub