I made an action to automatically format python code

Why

• When developing as a team, there is a big difference in code format

• Some people do it, others don't

• Different formatter

• I don't want to commit code formatting only

• I want to eliminate the hassle of developers and the dependence on the local environment.

• I don't want to depend on the local environment for libraries such as black and autopep

• I don't want to depend on editors such as vscode and emacs

• I wanted to touch github actions

• I thought it was just right for the first time

What

• What I made
• When pushing to the specified branch, search for the specified * .py code (in this example, workspace/python or less) and execute code formatting with black on the target python file.
• Assuming pull request → merge, execute the above code formatting even when it is merged to the merge destination branch.
• Repository
• Premise
• Use black for code formatting
• There are two branches, main/develop.
• Directory structure
• code-format.yml is the content of this action

├─.github
│  └─workflows
│          code-format.yml
│
└─python
    │  pyproject.toml
    │
    └─source
            a.py
            b.py

How

• code-format.yml is as follows

code-format.yml

name: python auto code format

on:
  push:
    branches: 
      - main
      - develop
    paths:
      - 'python/**'

  workflow_dispatch:

jobs:
  black:
    name: Check code style with Black
    runs-on: ubuntu-latest
    defaults:
      run:
        working-directory: ./python
    steps:    
      - name: Checkout
        uses: actions/checkout@v2
      - name: Set up Python 3.6.8
        uses: actions/setup-python@v2
        with:
          python-version: 3.6.8
      - name: Install black
        run: pip install black
      - name: run code format
        run: find . -type f -name "*.py" | xargs black
      - name: git settings
        run: |
          git config --local user.email "github-actions[bot]@users.noreply.github.com"
          git config --local user.name "github-actions[bot]"
      - name: Extract branch name
        id: extract_branch
        run: echo "##[set-output name=BRANCH_NAME;]$(echo ${GITHUB_REF#refs/heads/})"
      - name: commit
        run: git commit -m "python modules changed auto format." -a || echo "No changes to commit."
      - name: push
        run: |
          echo target branch is ${{ steps.extract_branch.outputs.BRANCH_NAME }}
          git pull
          git push origin ${{ steps.extract_branch.outputs.BRANCH_NAME }}

• Confirmation method

1. From the develop branch, create a suitable topic branch
2. Edit the appropriate code (b.py this time) in the appropriate topic branch (break the format) 3. commit & push
3. Generate pull request on github
4. Appropriate topic branch → merge into develop
5. Action runs
6. b.py in the develop branch is pushed in code-formatted state

• Actions

• Commit history of develop branch

• It's a bit confusing, but below, you can see that the history of commits by github actions remains and it is well formatted.

lastly This time, I assumed the topic branch → develop branch, but the same applies to develop → main. Also, in this case, actions will run even if you commit directly to the main or develop branch.