Updating Your Website Via GitHub Actions

For several years I maintained a subdomain on my website where I kept a list of all the books I had read, organized by year. The site was completely hand coded—no CMS involved, no frameworks, just HTML, CSS, and a little JavaScript.

While having the list was pleasing, updating the site was tedious at times. Copy and paste the previous book’s HTML table row, and replace all the values. Then commit the changes to the sites Git repository, and push the changes to GitHub. Finally sign into the host and update the site by updating the local working copy of the repository.

I have been wanting to automate this for some time, and, with a small Go application and a GitHub Action, it now requires far less interaction from me.

GitHub Action

My GitHub Action does these steps:

• Checks out the site’s Git repository
• Sets up Go
• Runs the Go application that builds the index.html file
• Commits the changes to the Git repository
• Sets up an ssh key using a Repository Secret
• Uses rsync to copy the updated site to the web host

Trigger

Currently I have the Action set to run anytime there is a push to the master branch. I am planning on revising this, to only run the Action when a pull request is merged into master. That will allow me to make multiple changes, without repeatedly running the automation.

name: Build Book Website

on:
  push:
    branches:
      - master

Checkout the Repository

The action runs in a “container” which itself is running the latest version of Ubuntu. GitHub provides a clause to specify the OS. GitHub also provides a library to checkout the repository.

jobs:
  # The "build" workflow
  build:
    runs-on: ubuntu-latest
      steps:
        # Checks out repository
      - uses: actions/checkout@v2

Setting up Go

The site is rebuilt using a small Go language application that reads the list of books from a comma-separated-value (CSV) file, and uses Go’s templating feature to build an HTML table with one row per book.

In order for the GitHub Action to run this application, Go needs to be setup. Again, a provided library makes getting Go installed quick.

- name: Setup Go
  uses: actions/setup-go@v2
  with:
    go-version: '1.18.3'

Running the Go Application

With Go installed, and the repository checked out, one command is all that is needed to run the Go application to rebuild the index.html file.

  # Run the Go application to update the site
- name: Run application
  run: go run main.go

Committing the Updated Repository

With the index.html file now updated the change needs to be committed to GitHub. I used an external action for this.

  # Commit the updated index.html file to the repository
- name: Commit updated index
  uses: EndBug/add-and-commit@v9
  with:
    add: 'site/index.html'
    author_name: GitHub Action
    author_email: root@zanshin.net
    message: 'Updated index.html with new listing(s)'
    push: true

There is only one file updated by the Go application, so I’m able to be specific about what is added. push: true is the default, but I put it here to be unambiguous. The Endbug/add-and-commit repository has more information about using this action.

Setting up an ssh Key

Getting an ssh key setup so that rsync can transfer the site from GitHub to the web host was the trickiest part of the entire action. I closely followed Deploying to a server via SSH and Rsync in a GitHub Action to get this working.

Remember, the action is running inside an Ubuntu container, and this will be a different container each time the action executes. The steps in zellwk.com’s article demonstrate how to use repository secrets to put the private half of an ssh key pair in the Ubuntu container, and how to update the .ssh/``known_hosts file. With all the pieces in place, here is the code for setting up the ssh key.

{% raw %}
  # Install the private half of our SSH key via a repository secret
- name: Install SSH Key
  uses: shimataro/ssh-key-action@v2
  with:
    key: {{ secrets.SSH_PRIVATE_KEY }}
    known_hosts: 'just-a-place-holder-so-we-dont-get-errors'

  # Update the know_hosts file
- name: Adding Known Hosts
  run: ssh-keyscan -H ${{ secrets.SSH_HOST }} >> ~/.ssh/known_hosts
{% endraw %}

rsync the Site to the Web Host

The final step uses rsync to copy the updated site to the web host. I restructured my repository to have all the site specific files in a site subdirectory. This makes it possible to copy the site and not the Go application and associated files to the web host.

{% raw %}
  # Use rsync to copy the repo to the host
- name: Deploy with rsync
  run: rsync -avz ./site/ ${{ secrets.SSH_USER }}@${{ secrets.SSH_HOST }}:/usr/home/mnichols/public_html/books
{% endraw %}

The Complete build.yaml Action

Here is my complete build.yaml action.