A lightweight, tool-agnostic CI/CD flow with GitHub Actions

Agnostic tooling is the clever notion that you should be able to run your code in various environments. With many continuous integration and continuous development (CI/CD) apps available, agnostic tooling gives developers a big advantage: portability.

Of course, having your CI/CD work everywhere is a tall order. Popular CI apps for GitHub repositories alone use a multitude of configuration languages spanning Groovy, YAML, TOML, JSON, and more… all with differing syntax, of course. Porting workflows from one tool to another is more than a one-cup-of-coffee process.

The introduction of GitHub Actions has the potential to add yet another tool to the mix; or, for the right set up, greatly simplify a CI/CD workflow.

Prior to this article, I accomplished my CD flow with several lashed-together apps. I used AWS Lambda to trigger site builds on a schedule. I had Netlify build on push triggers, as well as run image optimization, and then push my site to the public Pages repository. I used Travis CI in the public repository to test the HTML. All this worked in conjunction with GitHub Pages, which actually hosts the site.

I’m now using the GitHub Actions beta to accomplish all the same tasks, with one portable Makefile of build instructions, and without any other CI/CD apps.

Appreciating the shell

What do most CI/CD tools have in common? They run your workflow instructions in a shell environment! This is wonderful, because that means that most CI/CD tools can do anything that you can do in a terminal… and you can do pretty much anything in a terminal.

Especially for a contained use case like building my static site with a generator like Hugo, running it all in a shell is a no-brainer. To tell the magic box what to do, we just need to write instructions.

While a shell script is certainly the most portable option, I use the still-very-portable Make to write my process instructions. This provides me with some advantages over simple shell scripting, like the use of variables and macros, and the modularity of rules.

I got into the nitty-gritty of my Makefile in my last post. Let’s look at how to get GitHub Actions to run it.

Using a Makefile with GitHub Actions

To our point on portability, my magic Makefile is stored right in the repository root. Since it’s included with the code, I can run the Makefile locally on any system where I can clone the repository, provided I set the environment variables. Using GitHub Actions as my CI/CD tool is as straightforward as making Make go worky-worky.

I found the GitHub Actions workflow syntax guide to be pretty straightforward, though also lengthy on options. Here’s the necessary set up for getting the Makefile to run.

The workflow file at .github/workflow.yml contains the following:

name: make-master

on:
  push:
    branches:
      - master
  schedule:
    - cron: '20 13 * * *'

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@master
        with:
          fetch-depth: 1
      - name: Run Makefile
        env:
          TOKEN: ${{ secrets.TOKEN }}
        run: make all

I’ll explain the components that make this work.

Triggering the workflow

Actions support multiple triggers for a workflow. Using the on syntax, I’ve defined two triggers for mine: a push event to the master branch only, and a scheduled cron job.

Once the workflow.yml file is in your repository, either of your triggers will cause Actions to run your Makefile. To see how the last run went, you can also add a fun badge to the README.

One hacky thing

Because the Makefile runs on every push to master, I sometimes would get errors when the site build had no changes. When Git, via my Makefile, attempted to commit to the Pages repository, no changes were detected and the commit would fail annoyingly:

nothing to commit, working tree clean
On branch master
Your branch is up to date with 'origin/master'.
nothing to commit, working tree clean
Makefile:62: recipe for target 'deploy' failed
make: *** [deploy] Error 1
##[error]Process completed with exit code 2.

I came across some solutions that proposed using diff to check if a commit should be made, but this may not work for reasons. As a workaround, I simply added the current UTC time to my index page so that every build would contain a change to be committed.

Environment and variables

You can define the virtual environment for your workflow to run in using the runs-on syntax. The obvious best choice one I chose is Ubuntu. Using ubuntu-latest gets me the most updated version, whatever that happens to be when you're reading this.

GitHub sets some default environment variables for workflows. The actions/checkout action with fetch-depth: 1 creates a copy of just the most recent commit your repository in the GITHUB_WORKSPACE variable. This allows the workflow to access the Makefile at GITHUB_WORKSPACE/Makefile. Without using the checkout action, the Makefile won't be found, and I get an error that looks like this:

make: *** No rule to make target 'all'.  Stop.
Running Makefile
##[error]Process completed with exit code 2.

While there is a default GITHUB_TOKEN secret, this is not the one I used. The default is only locally scoped to the current repository. To be able to push to my separate GitHub Pages repository, I created a personal access token scoped to public_repo and pass it in as the secrets.TOKEN encrypted variable. For a step-by-step, see Creating and using encrypted secrets.

Portable tooling

The nice thing about using a simple Makefile to define the bulk of my CI/CD process is that it’s completely portable. I can run a Makefile anywhere I have access to an environment, which is most CI/CD apps, virtual instances, and, of course, on my local machine.

One of the reasons I like GitHub Actions is that getting my Makefile to run was pretty straightforward. I think the syntax is well done - easy to read, and intuitive when it comes to finding an option you’re looking for. For someone already using GitHub Pages, Actions provides a pretty seamless CD experience; and if that should ever change, I can run my Makefile elsewhere. ¯\_(ツ)_/¯