Dynamic parallel matrix

Job matrix creates multiple job runs that are based on the combinations of the variables. Sometimes we want a dynamic number of matrix jobs, which requires a JSON array as an output. Here we use json and glob modules in Python to generate that JSON list.¹²

name: Show text files with dynamic parallel matrix

on:
  push:
    branches:
    - main

jobs:
  setup:
    runs-on: ubuntu-latest
    outputs:
      matrix: ${{ steps.set-matrix.outputs.matrix }}
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
      - name: List text files as a JSON array
        id: set-matrix
        run: echo "matrix=$(python -c 'import glob, json; print(json.dumps(glob.glob("*.txt")))')" >> $GITHUB_OUTPUT
  execute:
    needs: setup
    strategy:
      fail-fast: false
      matrix:
        textfile: ${{ fromJSON(needs.setup.outputs.matrix) }}
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
      - name: Print text file
        run: cat ${{ matrix.textfile }}

---

1. https://stackoverflow.com/questions/3207219/how-do-i-list-all-files-of-a-directory ↩

2. https://stackoverflow.com/questions/10234327/convert-bash-ls-output-to-json-array ↩

Comments