Automating Code Changes via GitHub Actions Making Pull Requests

You’ve probably been depending on automated pull requests from Dependabot, but how about making your own pull requests from GitHub actions? This capability can be used for automation that looks for changes, then updates files in your own repository with little to no additional setup needed.

In dblock/lost-robbies the workflow checks for new sales and raises a PR after updating the JSON data and the README.md.
In opensearch-project/project-meta the workflow enumerates public repositories in the opensearch-project organization and adds new repos to a .meta file.

Below are some implementation details from opensearch-project/project-meta.

GitHub Action Setup

The job is executed on all changes to main and daily at midnight.

name: Check for new Project Repos
on:
  push:
    branches:
      - main  
  schedule:
    - cron: "0 0 * * *"

Permissions and Tokens

The job checks out code, and needs a GITHUB_TOKEN in env. to make pull requests.

jobs:
  check-project-repos:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Update project repositories
  env:
    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Generating a PR Title and Body

At first I was hard-coding PR titles and commit messages. That’s not ideal. Compare the following PRs. The second version is much more specific!

This can be achieved by setting an environment variable during the workflow execution by piping it into $GITHUB_ENV, and reusing it in the PR.

echo REPOS_ADDED=$(git diff --unified=0 .gitignore | grep '+/' | cut -f2 -d'/' | paste -sd ',' - | sed "s/,/, /g" | sed 's/\(.*\),/\1 and/') >> $GITHUB_ENV

The workflow modifies .gitignore by adding lines to it, such as /cross-cluster-replication/.
Find all additions that start with +/ using | grep '+/'.
Extract the name of each addition with | cut -f2 -d'/', e.g. cross-cluster-replication.
Combine all additions into a comma-separated list with | paste -sd ',' -.
Add a space after each comma with | sed "s/,/, /g" |.
Replace the last comma by an and with | sed 's/$.*$,/\1 and/'.
Pipe everything into REPOS_ADDED= with echo REPOS_ADDED=$(...) >> $GITHUB_ENV.

Make a Pull Request

- name: Create Pull Request
  uses: peter-evans/create-pull-request@v3
  with:
    commit-message: Added ${{ env.REPOS_ADDED }}.
    delete-branch: true
    title: 'Added ${{ env.REPOS_ADDED }}.'
    body: |
      Added ${{ env.REPOS_ADDED }}.
- name: Check outputs
  run: |
    echo "Pull Request Number - ${{ steps.cpr.outputs.pull-request-number }}"
    echo "Pull Request URL - ${{ steps.cpr.outputs.pull-request-url }}"

Profit

See opensearch-project/project-meta#7 for an example.

Daniel Doubrovkine

Automating Code Changes via GitHub Actions Making Pull Requests github