How to Run a Matrix Build in Azure Pipelines

Azure Pipelines fans a job across combinations with strategy: matrix, each exposing its values as variables.

Define named matrix legs under strategy: matrix. Each leg becomes a parallel job copy; the leg's key/value pairs are available as variables.

Matrix across Node versions

Each named leg sets variables consumed by the steps; maxParallel caps concurrency.

jobs:
  - job: test
    strategy:
      maxParallel: 3
      matrix:
        node18:
          NODE_VERSION: '18.x'
        node20:
          NODE_VERSION: '20.x'
        node22:
          NODE_VERSION: '22.x'
    pool: { vmImage: 'ubuntu-latest' }
    steps:
      - task: NodeTool@0
        inputs: { versionSpec: $(NODE_VERSION) }
      - script: npm ci && npm test

Gotchas

• Each matrix leg is named; that name shows in the run and must be unique within the job.
• maxParallel limits concurrent legs - useful to stay within your parallel-job license.
• For test slicing (not version fan-out), set parallel: N on the job and use System.JobPositionInPhase/System.TotalJobsInPhase.

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