A GitHub Action for installing, configuring and running hardware-accelerated Android Emulators on macOS virtual machines.

The old ARM-based emulators were slow and are no longer supported by Google. The modern Intel Atom (x86 and x86_64) emulators require hardware acceleration (HAXM on Mac & Windows, QEMU on Linux) from the host to run fast. This presents a challenge on CI as to be able to run hardware accelerated emulators within a docker container, KVM must be supported by the host VM which isn't the case for cloud-based CI providers due to infrastructural limits. If you want to learn more about this, here's an article I wrote: Running Android Instrumented Tests on CI.

The macOS VM provided by GitHub Actions has HAXM installed so we are able to create a new AVD instance, launch an emulator with hardware acceleration, and run our Android tests directly on the VM. You can also achieve this on a self-hosted Linux runner, but it will need to be on a compatible instance that allows you to enable KVM - for example AWS EC2 Bare Metal instances.

This action automates the process by doing the following:

• Install / update the required Android SDK components including build-tools, platform-tools, platform (for the required API level), emulator and system-images (for the required API level).
• Create a new instance of AVD with the provided configurations.
• Launch a new Emulator with the provided configurations.
• Wait until the Emulator is booted and ready for use.
• Run a custom script provided by user once the Emulator is up and running - e.g. ./gradlew connectedCheck.
• Kill the Emulator and finish the action.

It is recommended to run this action on a macOS VM, e.g. macos-latest, macos-10.15 or macos-11 to take advantage of hardware acceleration support provided by HAXM.

A workflow that uses android-emulator-runner to run your instrumented tests on API 29:

jobs:
  test:
    runs-on: macos-latest
    steps:
      - name: checkout
        uses: actions/checkout@v3

      - name: run tests
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: 29
          script: ./gradlew connectedCheck

We can also leverage GitHub Actions's build matrix to test across multiple configurations:

jobs:
  test:
    runs-on: macos-latest
    strategy:
      matrix:
        api-level: [21, 23, 29]
        target: [default, google_apis]
    steps:
      - name: checkout
        uses: actions/checkout@v3

      - name: run tests
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: ${{ matrix.api-level }}
          target: ${{ matrix.target }}
          arch: x86_64
          profile: Nexus 6
          script: ./gradlew connectedCheck

If you need specific versions of NDK and CMake installed:

jobs:
  test:
    runs-on: macos-latest
    steps:
      - name: checkout
        uses: actions/checkout@v3

      - name: run tests
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: 29
          ndk: 21.0.6113669
          cmake: 3.10.2.4988404
          script: ./gradlew connectedCheck

We can significantly reduce emulator startup time by setting up AVD snapshot caching:

1. add a gradle/gradle-build-action@v2 step for caching Gradle, more details see #229
2. add an actions/cache@v3 step for caching the avd
3. add a reactivecircus/android-emulator-runner@v2 step to generate a clean snapshot - specify emulator-options without no-snapshot
4. add another reactivecircus/android-emulator-runner@v2 step to run your tests using existing AVD / snapshot - specify emulator-options with no-snapshot-save

jobs:
  test:
    runs-on: macos-latest
    strategy:
      matrix:
        api-level: [21, 23, 29]
    steps:
      - name: checkout
        uses: actions/checkout@v3

      - name: Gradle cache
        uses: gradle/gradle-build-action@v2
        
      - name: AVD cache
        uses: actions/cache@v3
        id: avd-cache
        with:
          path: |
            ~/.android/avd/*
            ~/.android/adb*
          key: avd-${{ matrix.api-level }}

      - name: create AVD and generate snapshot for caching
        if: steps.avd-cache.outputs.cache-hit != 'true'
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: ${{ matrix.api-level }}
          force-avd-creation: false
          emulator-options: -no-window -gpu swiftshader_indirect -noaudio -no-boot-anim -camera-back none
          disable-animations: false
          script: echo "Generated AVD snapshot for caching."

      - name: run tests
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: ${{ matrix.api-level }}
          force-avd-creation: false
          emulator-options: -no-snapshot-save -no-window -gpu swiftshader_indirect -noaudio -no-boot-anim -camera-back none
          disable-animations: true
          script: ./gradlew connectedCheck