Using bashew in GitHub Actions

GitHub Actions, used in countless CI/CD setups, are a good example of the ubiquity of bash scripting. Most of the run: lines in an Action YML document are nothing but (a sequence of) bash command lines.

I knew this could be a good match for bashew scripts-based bash scripts, but I only found some time to try that out last weekend.

TL;DR: bashew scripts are a great way to streamline your GitHub Actions

shot-scraper

I got inspired by Automating screenshots using shot-scraper via Hacker News. The shot-scraper documentation describes how to set it up for using GitHub Actions to do the actual screen grabbing. I used that as a starting point and I distilled it into an efficient example project: pforret/bashew_github_action.

bashew_github_action

I created 3 sub commands in the bashew_github_action.sh script:

• gha:before: does the GitHub Action setup (in this case: check if Python is installed, install shot-scraper and do initial shot-scraper setup)
• gha:execute: runs the actual payload. In this case: use shot-scraper to get screenshots of a number of websites
• gha:after: save the results by doing an automatic git commit and git push.

The YML code to run each of them in sequence, is super easy:

    - name: gha:before
      run: |
        ./bashew_github_action.sh gha:before
    - name: gha:execute
      run: |
        ./bashew_github_action.sh gha:execute
    - name: gha:after
      run: |-
        ./bashew_github_action.sh gha:after

This is one of the screenshots it generates:

Advantages:

Using a bashew script to streamline your GitHub Actions is a good idea because:

• Single Responsibility. You edit your setup code in the same file as the payload or the wrap-up code. You don’t touch the action.yml file anymore after initial setup.
• Cleaner Code. The YML syntax forces you to a do this && do that && do the other one-liner format. A script allows you to do if/then, for/do, while/do, recursion … in an easy and clean way.
• Easy Debugging. bashew has built-in support for log files and optional verbose mode. It also cleans up log files after 30 days, so they don’t clog up your repo.
• Self-Contained. You don’t need external libraries or runtimes. bash runs on most Action Runners (Linux/MacOS) and each bashew script contains its entire library of functions.

Try it out

# install bashew, if necessary
basher install pforret/bashew
# add a new bashew script to your project
bashew script
# add subcommands setup/payload/wrapup, or gha:before,gha:execute,gha:after

or even easier:

# clone the example repo
git clone https://github.com/pforret/bashew_github_action.git
# copy bashew_github_action.sh and .github/workflows/shots.yml to your project
# start editing the gha:before and gha:execute subcommands
  gha:before)
    [[ -z "${RUNNER_OS:-}" ]] && IO:die "Only run inside a Github Action"
    Os:require pip python3
    pip install shot-scraper
    shot-scraper install
    ;;