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  brew install act

Test it out

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  cd $(mktemp -d)
  git clone https://github.com/cplee/github-actions-demo
  cd github-actions-demo

Then run

act

I chose the medium instance. It seemed to pass.

Listing out the repos

My first test is to print out all of my repos in the run. This isn't that exiting but it's a good way to test it out.

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  name: My workflow
  on: [push, pull_request]
  jobs:
    test:
      runs-on: ubuntu-latest
      steps:
        - uses: actions/checkout@v4
        - run: gh repo list
          env:
            GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Run it like

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  act --container-architecture linux/amd64

This gives a gh not found error, which is not great, so lets switch to the full image instead of the medium one.

Pull it manually since there's no progress report otherwise

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  docker pull catthehacker/ubuntu:full-latest --platform=linux/amd64

Then fire it up:

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  act -s GITHUB_TOKEN="$(gh auth token)" \
      -P ubuntu-latest=catthehacker/ubuntu:full-latest \
      --container-architecture linux/amd64

This also required me to increase the disk image size for the vm that I'm running all this stuff under.

Ultimately, the fact that act doesn't run exactly the same as the github runners is frustrating.

Creating a quick generator

We'll load in a TEMPLATE.md file, and then replace the comments repo activity and feed: url with a list of things that we get from github or from an external rss feed.

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  bundle init
  bundle add feedjira httparty

Then generate.rb:

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  #!/bin/env ruby

  require 'bundler'
  require 'feedjira'
  require 'httparty'
  require 'date'

  template = File.read("TEMPLATE.md")

  if( template =~ /<!-- repo activity -->/  )
    puts "Replacing repo activity"
    activity_json = `gh repo list --json nameWithOwner,description,updatedAt --source --visibility public`
    activity = JSON.parse(activity_json)[0..10].collect do |repo|
      date = DateTime.parse(repo["updatedAt"]).strftime("%Y-%m-%d")
      " - #{date}: [#{repo["nameWithOwner"]}](https://github.com/#{repo["nameWithOwner"]}) - #{repo["description"]}"
    end.join("\n")

    template.gsub!("<!-- repo activity -->", activity)
  end

  template.gsub!(/<!-- feed: (.*) -->/ ) do |match|
    puts "Looking for feed #{$1}"
    xml = HTTParty.get($1).body
    feed = Feedjira.parse(xml)
    posts = feed.entries[0..10].collect do |entry|
      date = entry.published.strftime("%Y-%m-%d")
      " - #{date}: [#{entry.title}](#{entry.url})"
    end.join("\n")

    posts
  end

  puts "Writing to README.md"
  File.write("README.md", template)

  # system("cat README.md")

Test it locally to make sure that it runs every so nicely.

The build script

A couple of points

  • Adding workflow_dispatch lets you trigger this in the admin tool on github proper
  • The default GITHUB_TOKEN doesn't show visibility to other repos. go to settings, and copy your personal token in as a secret (called WILL_TOKEN below) to be able to have the gh command see your other repos
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  name: Build Readme
  on:
    push:
    workflow_dispatch: # This lets you trigger the workflow manually
    schedule:
      - cron: "0 * * * *"
  jobs:
    build:
      runs-on: ubuntu-latest
      steps:
        - uses: actions/checkout@v4
        - uses: ruby/setup-ruby@v1
          with:
            ruby-version: "3.3" # Not needed with a `.ruby-version` or `.tool-versions`
            bundler-cache: true # runs 'bundle install' and caches installed gems automatically
        - run: bundle exec ruby generate.rb
          env:
            GH_TOKEN: ${{ secrets.WILL_TOKEN }} # This is from gh-auth-token and set in the repo secrets
        - name: Commit and push if README changed
          run: |-
            git pull origin main
            git diff
            git config --global user.email "readme-bot@example.com"
            git config --global user.name "README-bot"
            git add README.md
            git commit -m "Updated content" || exit 0
            git push
          env:
            GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

And now you can see my updated github profile!

Thoughts

cron jobs on github are fun. A cool idea would be to have it generate a status page for all your sites and give you a notification if something went down.