Trenton Broughton danger: high entropy

Automatic Hugo Site Deployments With CircleCI

code hugo

Generating static sites with Hugo is easy enough, but I wanted something a little more automated. I also wanted to deploy my site to Github Pages from another computer (or even my phone) without needing to run the hugo command locally and pushing the generated code back to Github. If you are unfamiliar with Github Pages, check out the introduction.

Prep Work – Getting Things Set Up

CircleCI uses Docker containers to run CI jobs, so I knew that I would need a Hugo image to build my site. There are quite a few listed on Docker Hub, but for completeness, I went ahead and set up my own. This step can be skipped, just specify which ever image you wish to use in your CircleCI configuration file.

FROM debian:stretch
RUN apt-get update && apt-get install -y git ssh curl
RUN curl -L -o hugo.deb "${HUGO_VERSION}/hugo_extended_${HUGO_VERSION}_Linux-64bit.deb" && dpkg -i hugo.deb
CMD [hugo]

This git repo is built automatically by Docker Hub, and results in the image trenton/hugo-extended.

Building the Pipeline

What the Pipeline Will Do

The process that this pipeline will follow should be something like this:

  1. Checkout the new changes from Github
  2. Checkout the output branch (master in my case) to another directory
  3. Run Hugo to render the site sending the output to the directory containing my output branch
  4. If we are going to publish, commit any changes to the output branch, and push them back to Github

Pipeline Goals

I had a couple of goals for my pipeline deployments:

  1. I want to test that any branch generates without errors.
  2. I only want my main branch (which is called content) to actually publish my site.
  3. I don’t want rendered content to trigger CI builds.
  4. I don’t want the pipeline to attempt to deploy if nothing has actually changed.

The Pipeline

My final pipeline is rather lengthy, so I will not copy it in its entirety here. You can view it on this site’s Github Repo. I will point out a few key areas that relate to my goals, though.

The workflows section controls what jobs are actually run and when:

  version: 2
      - build # This job will run on any branch and fulfils goal ⓵
      - deploy:
            - build
              only: content # The deploy job will only run on the main branch for goal ⓶

In order to prevent the pipeline to attempt to run on my generated branch, I add the text [ci skip] to the commit message on my generated branch (goal ⓷).

git add . && git commit -m "Automatic deployment [ci skip]" && git push

Finally, to check if anything has changed (goal ⓸), I wrapped the entire command in an if statement:

if [[ -n $(git status --porcelain) ]]; then

Side Notes

You might have noticed that I add an ssh key in one of the steps:

- add_ssh_keys:
        - "cc:c9:30:35:0a:9e:22:50:67:2f:e4:61:74:6e:9b:4c"

This is because CircleCI will create a read only key to checkout and test your code, but I need to make a commit and push back to Github. To get around this, I created another deploy key with write permissions to this repository. If you follow these steps, you will need to change the fingerprint to match your own deploy key.

You also will see that there is a save_cache step and a restore_cache step in the two jobs. This is because each job runs in an isolated container, and has no persistent state that is preserved between the jobs. Using the cache allows me to avoid building the site twice (once in each step).


That’s it! Now I can write a post or update templates directly on Github without needing to checkout the changes and run Hugo manually. Feel free to use and adapt this pipeline to suit your needs.