How to create a Github Action to publish a Ruby gem to Rubygems.org

Step #1 | Generate Rubygems API Key

1. Log in to your rubygems.org account

2. Go to Settings

3. Click on API KEYS

4. Click New API key

Copy your key in a safe place you can't retrieve it from rubygems.org later.

Step #3 | Create a Secret for your GitHub repository

1. In your Github repository, go to Settings

2. Go to Secrets from the sidebar

3. Press New repository secret button

4. In the Name field put: GEM_HOST_API_KEY

5. In the Value field put your rubygems API key

6. Press Add secret button

Step #4 | Create a GitHub Action

1. In your repository, Go to Actions tab

2. Press New workflow

3. Select set up a workflow yourself

4. Paste the following in it and save

gem-push.yml

name: Push Ruby Gem

on: workflow_dispatch

jobs:
  release:
    runs-on: ubuntu-latest
    env:
      GEM_HOST_API_KEY: ${{ secrets.GEM_HOST_API_KEY }}
    steps:
      - uses: actions/checkout@v2
        with:
          fetch-depth: 0 # need all the commits
      - uses: ruby/setup-ruby@v1
        with:
          ruby-version: .ruby-version
          bundler-cache: true
      - uses: actions/setup-node@v2
      - name: Configure Git
        run: |
          git config --local user.email "[e-mail]"
          git config --local user.name "GitHub Action"
      - name: Bump and Commit
        run: |
          yarn add standard-version
          yarn run standard-version
          git push --follow-tags
      - name: Push to rubygems.org
        run: |
          gem build *.gemspec
          gem push *.gem

This will create a file under your repository root directory .github/workflows/gem-push.yml

5. Under your repository root directory create .ruby-version file and put the ruby version you desire

6. Under your repository root directory create .versionrc.js file and put the following

.versionrc.js

version_rb = {
  "filename": "lib/[CHANGE-ME]/version.rb",
  "updater": {
    readVersion: function(contents) {
      match = contents.match(/^\s*VERSION = ["'](.+)["']$/m)
      return match[1]
    },
    writeVersion: function(contents, version) {
      currentVersion = this.readVersion(contents)
      // this isn't the most reliable, but meh
      return contents.replace(currentVersion, version)
    },
  },
}

module.exports = {
  "bumpFiles": [version_rb],
  "packageFiles": [version_rb],
  "preset": "angular",
}

This script will update your repository version

Step # 5 | Run your Action's workflow

1. Go to Actions tab

2. Select the workflow and press Run.

Resources

GitHub Workflow For Automated Gem Releasestom_dalling

Automating Ruby Gem Releases with GitHub ActionsAndrew Mason