GitHub Action - Android Emulator Runner

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 can be fast, but rely on two forms of hardware acceleration to reach their peak potential: Graphics Acceleration, e.g. emulator -gpu host and Virtual Machine(VM) Acceleration, e.g. emulator -accel on. Note: GPU and VM Acceleration are two different and non-mutually exclusive forms of Hardware Acceleration.

This presents a challenge when running emulators on CI especially when running emulators within a docker container, because Nested Virtualization must be supported by the host VM which isn't the case for most cloud-based CI providers due to infrastructural limits. If you want to learn more about Emulators on CI, here's an article Yang wrote: Running Android Instrumented Tests on CI.

A note on VM Acceleration and why we don't need HAXM anymore

According to this documentation, "on Mac OS X v10.10 Yosemite and higher, the Android Emulator uses the built-in Hypervisor.Framework by default, and falls back to using Intel HAXM if Hypervisor.Framework fails to initialize." This means that HAXM is only needed to achieve VM Acceleration if this default Hypervisor is not available on macOS machines.

Note: Manually enabling and downloading HAXM is not recommended because it is redundant and not needed (see above), and for users of macOS 10.13 High Sierra and higher: macOS 10.13 disables installation of kernel extensions by default. Because Intel HAXM is a kernel extension, we would need to manually enable its installation on the base runner VM. Furthermore, manually trying to install HAXM on a Github Runner brings up a popup which further hinders tests from running.

Purpose

This action helps automate and configure the process of setting up an emulator and running your tests 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.

Usage & Examples

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

Configurations

Default emulator-options: -no-window -gpu swiftshader_indirect -no-snapshot -noaudio -no-boot-anim.

Can I use this action on Github Hosted Linux VMs?

The short answer is yes but on Github-hosted Linux runners it's expected to be a much worse experience (on some newer API levels it might not work at all) than running it on macOS, because of the current lack of hardware acceleration support. You can get it running much faster on self-hosted Linux runners but only if the underlying instances support KVM (which most don't). Things might be better on the newer Larger runners but they are still in Beta. It is possible to use this Action with hardware accelerated Linux VMs hosted by a third-party runner provider.

For a longer answer please refer to this issue.

Who is using Android Emulator Runner?

These are some of the open-source projects using (or used) Android Emulator Runner:

• coil-kt/coil
• cashapp/sqldelight
• square/workflow-kotlin
• square/retrofit
• natario1/CameraView
• natario1/Transcoder
• chrisbanes/insetter
• slackhq/keeper
• android/compose-samples
• ReactiveCircus/streamlined
• ReactiveCircus/FlowBinding
• JakeWharton/RxBinding
• vinaygaba/Learn-Jetpack-Compose-By-Example
• ashishb/adb-enhanced
• vgaidarji/ci-matters
• simpledotorg/simple-android
• cashapp/copper
• square/radiography
• Shopify/android-testify
• square/leakcanary
• hash-checker/hash-checker
• hash-checker/hash-checker-lite
• Kiwix/kiwix-android
• wikimedia/apps-android-wikipedia
• google/android-fhir
• google/accompanist
• dotanuki-labs/norris
• tinylog-org/tinylog
• hzi-braunschweig/SORMAS-Project
• ACRA/acra
• bitfireAT/davx5-ose

If you are using Android Emulator Runner and want your project included in the list, please feel free to open a pull request.