github actions conditional environment variables

Update 1/4/2023: The original psot contained an error that did not have proper variable scope in mind when working with the builtin GitHub actions variables. The code has since been fixed, though the solution that I recommend to avoid the verbosity of this setup is still recommended.

Working with GitHub actions is often nicer than GitLab's CI pipelines because it offers readability (with less verbose includes), simpler stage dependencies, and less reliance on the rules flag.

However, when creating an environment variable for stages, I found that I couldn't follow the documentation on the site. This was related to using the $GITHUB_ENV to do environment changes from within a job step, oddly enough it would fail stating that it was an invalid name.

Example configuration:

  env_vars:
    runs-on: ubuntu-latest
    steps:
      - name: Set Stage
        run: |
          echo "Discovering the environment stage:"
          if [[ ${{ github.ref == 'refs/heads/master' }} ]]; then
            echo "STAGE=prod" >> $GITHUB_ENV
          else
            echo "STAGE=dev" >> $GITHUB_ENV
          fi
          echo "Environment stage is set:"
          echo "${{ GITHUB_ENV }}"

Note: I break this down below as well, but we essentially check the head reference for our master branch, then return the value as either prod if it matches, or dev otherwise.

Documentation regarding the environment variable creation

Working around GITHUB_ENV in a cleaner way

My workaround for this environment variable setup was to utilize a ternary operator styled approach within the env stage at a global level.

Example for a dev/prod configuration:

env:
  STAGE: ${{ github.ref == 'refs/heads/master' && 'prod' || 'dev' }}

Breaking down what's written above, we have:

A STAGE variable being set
The github.ref head is checked against our master branch
If the branch matches master, then use prod
If the branch doesn't match master, then use dev

Bonus, echoing our vars after setting them

I think it's important to have some verbosity when running CI/CD pipelines, especially when extending functionality. Often times when we're setting up environments for deployment, if we don't know "what we have" then we won't be able to determine missing configurations.

As such, I like to include a job to echo our vars (not our secrets) to keep things transparent.

jobs:

  env_vars:
    runs-on: ubuntu-latest
    steps:
    - name: Echo Env Vars through Context
      run: |
        echo "$GITHUB_CONTEXT"