How To Specify Pairs of Items in GitHub Actions Matrix Strategies

Came across this and wasn’t aware of it (though it makes total sense in retrospect), so I figured I’d pass the tip along.

Background: What is a Matrix Strategy in GitHub Actions?

Sometimes you need an GitHub Action Job to run for multiple combinations of items. In my case, I was looking to run an action to publish a Docker container across a combination of Ruby, Node, and GitHub Pages versions.

Running an action in this way will create an instance of that job for every combination in the matrix entries:

jobs:
  build_release:
    name: "Build and Release"
    strategy:
      matrix:
        RUBY_VERSION: [2.7.3]
        NODE_MAJOR_VERSION: [16, 18]
        GITHUB_PAGES_VERSION: [226]
    runs-on: ubuntu-latest
    env:

      RUBY_VERSION: ${{ matrix.RUBY_VERSION }}
      NODE_MAJOR_VERSION: ${{ matrix.NODE_MAJOR_VERSION }}
      GITHUB_PAGES_VERSION: ${{ matrix.GITHUB_PAGES_VERSION }}

…But do we really want every combination?

Read the rest of this article at SeanKilleen.com!