Android emulator in docker/jenkins pipeline

Note

TL;DR - How to set up an Android emulator in Docker for Jenkins CI/CD — covering emulator AVD creation in Dockerfiles, boot-completion detection via adb shell getprop sys.boot_completed, and pipeline integration with Amarula Solutions’ Build shared library.

How do you create an Android emulator in Docker?

To create an emulator, use the following steps in DockerFile.

  1. Define Android version e.g. android-25

  2. Define emulator architecture e.g. arm, x86 etc

  3. Complete emulator package.

  4. Make .android directory in $JENKINS_HOME. This path will be used by android emulator to store data. If we don’t provide our path it will use ~/.android to store data and this path cannot be accessed without root access.

  5. Add ANDROID_AVD_HOME environment variable. Point variable to the directory created in point 4.

  6. Define unique emulator name and set it to EMULATOR_NAME environment variable.

  7. Create emulator using avdmanager command. Use EMULATOR_NAME defined in point 6 and ANDROID_EMULATOR_PACKAGE defined in point 3.

Example:

ARG ANDROID_VERSION="android-25"
ARG EMULATOR_ARCH="armeabi-v7a"
ARG ANDROID_EMULATOR_PACKAGE="system-images;${ANDROID_VERSION};google_apis;${EMULATOR_ARCH}"

RUN mkdir $JENKINS_HOME/.android
ENV ANDROID_AVD_HOME="/home/jenkins/.android/avd"
ENV EMULATOR_NAME="android_emulator"
RUN echo "no" | avdmanager --verbose create avd --force --name "${EMULATOR_NAME}" --device "pixel" -k "${ANDROID_EMULATOR_PACKAGE}"

How do you add an emulator start script?

Create a shell script and add the following lines in it.

Use emulator command to start emulator. Use EMULATOR_NAME environment variable(defined in step Create android emulator), to start the emulator.

Since emulator can take some time to boot, so we have to check if emulator is fully booted and ready to run app. For that we can use adb shell getprop sys.boot_completed command to check status of emulator in while loop.

Example Script:

adb devices | grep emulator | cut -f1 | while read line; do adb -s $line emu kill; done
emulator -avd "${EMULATOR_NAME}" -verbose -wipe-data -no-snapshot -no-window -no-audio &
while [ "$(adb shell getprop sys.boot_completed | tr -d '\r')" != "1" ]; do
    echo "Still waiting for boot.."
    sleep 1
done

We have to add this script in our Dockerfile, so that we can run it from Jenkins pipeline.

Example:

ADD script.sh /

How do you start the emulator from a Jenkins pipeline?

We can use the shell script created above to start the emulator from jenkins pipeline.

Example pipeline:

#!groovy

import com.amarula.build.Build

node('android-build') {
    def build = new Build(this, env, 'abc123')
    def repoUrl = "https://github.com/yourRepo"

    final def dockerImage = 'android-with-emulator:1.0'

    build.build(repoUrl, {

        sh 'chmod +x gradlew'

        sh '. /start_emulator.sh'
        sh './gradlew connectedAndroidTest'

    }, [branch: "master", history: true, dockerImage: dockerImage, gerritRemoteUrl: env.GERRIT_HTTPS_URL])
}

Tip

Need Android instrumentation tests in your CI/CD pipeline? Amarula Solutions builds Docker-based Android emulator environments integrated with Jenkins for automated UI and instrumentation testing. Contact our mobile DevOps team