How to Cache Maven .m2 in GitHub Actions

Maven downloads its entire dependency tree from scratch on a fresh runner unless the local repo is cached.

Use actions/setup-java with built-in Maven caching, or cache ~/.m2/repository directly keyed on pom.xml.

Steps

• Add actions/setup-java and set cache: maven for the simplest path.
• Or add an explicit actions/cache step over ~/.m2/repository.
• Key on hashFiles(**/pom.xml) with a restore-keys fallback.
• Run mvn -B verify so the cache populates on first use.

Workflow

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-java@v4
        with:
          distribution: temurin
          java-version: '21'
          cache: maven
      - run: mvn -B verify

Gotchas

• Avoid caching -SNAPSHOT artifacts you publish locally; they go stale and mask real failures.
• Use -B (batch mode) to keep logs clean and downloads deterministic.
• Latchkey keeps the Maven repository warm between runs so builds are cheaper and self-healing.

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