Automatically Generate Tags and Release Notes on Main Branch Merges Using GitHub Actions

2022-10-08

Introduction

In a previous article, I introduced a way to categorize release notes by the corresponding content.

👉 Categorize GitHub Repository Release Notes by Content for a Nice Look

In this article, I will show how to automatically generate tags and release notes using GitHub Actions when certain events are triggered.

The Workflow

Here is the entire GitHub Actions workflow I put together:

name: Generate release note

on:
  pull_request:
    branches:
      - main
    types:
      - closed

jobs:
  generate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Generate tag
        run: |
          export TAG_NAME=$(sed -n 6P pubspec.yaml | sed 's/version: //')
          git tag $TAG_NAME
          git push origin $TAG_NAME
          echo "TAG_NAME=$TAG_NAME" >> $GITHUB_ENV
      - name: Generate release note
        uses: softprops/action-gh-release@v1
        with:
          name: ${{ env.TAG_NAME }}
          tag_name: ${{ env.TAG_NAME }}
          generate_release_notes: true

Explanation of Each Step

Trigger

For this workflow, I set it to run when a pull request targeting the main branch is closed (merged).

There may also be cases where you want to create release notes when a branch such as release/* is merged or when a tag is pushed. Please adjust as necessary.

on:
  pull_request:
    branches:
      - main
    types:
      - closed

`actions/checkout@v3`

This action checks out the repository. I won’t go into detail since it’s commonly used.

`Generate tag`

Here, a tag is generated and pushed. In my case, I’m retrieving the version number, which will be the tag name, from the pubspec.yaml file of my Flutter app.

You can also get the tag name from branch names like release/* or tag/*. You can obtain the branch name from the github.ref context, so please adjust as needed.

Contexts - GitHub Docs

You can access context information in workflows and actions.

docs.github.com

export TAG_NAME=$(sed -n 6P pubspec.yaml | sed 's/version: //')
git tag $TAG_NAME
git push origin $TAG_NAME

Additionally, I want to use the tag name I created in the next step to create a release note, so I’m writing it to $GITHUB_ENV.

By writing environment variables to the environment file $GITHUB_ENV, subsequent steps can use the same environment variables. For more information, please read the official documentation.

Workflow commands for GitHub Actions - GitHub Docs

You can use workflow commands when running shell commands in a workflow or in an action’s code.

docs.github.com

echo "TAG_NAME=$TAG_NAME" >> $GITHUB_ENV

`Generate release note`

For automatically generating release notes, I used the softprops/action-gh-release action.

GitHub - softprops/action-gh-release: 📦 GitHub Action for creating GitHub Releases

📦 :octocat: GitHub Action for creating GitHub Releases - GitHub - softprops/action-gh-release: 📦 GitHub Action for creating GitHub Releases

github.com

I specify the release note name with name and the tag name with tag_name.

By setting generate_release_note to true, release notes will be automatically generated based on .github/release.yml. For more information on automatically generated release notes, please read:

自動生成リリースノート - GitHub Docs

GitHub リリースのリリースノートを自動的に生成できます

docs.github.com

- name: Generate release note
  uses: softprops/action-gh-release@v1
  with:
    name: ${{ env.TAG_NAME }}
    tag_name: ${{ env.TAG_NAME }}
    generate_release_notes: true

There are other settings available for softprops/action-gh-release, so I recommend reading the README for more details.

Finished！

With the above workflow set up, when a pull request targeting the main branch is merged, tags and release notes are indeed automatically generated by GitHub Actions!