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Language Guide: Android

6 days ago4 min read
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This document describes how to set up an Android project on CircleCI in the following sections.


This guide assumes the following:

Note: CircleCI offers an Android machine image available on CircleCI Cloud that supports x86 Android emulators and nested virtualization. Documentation on how to access it is available here. Another way to run emulator tests from a job is to consider using an external service like Firebase Test Lab. For more details, see the Testing With Firebase Test Lab section below.

Sample configuration for UI tests

Let’s walk through a sample configuration using the Android machine image. It is possible to use both orbs and to manually configure the use of the Android machine image to best suit your project.

# .circleci/config.yaml
version: 2.1 # to enable orb usage, you must be using circleci 2.1
# Declare the orbs you wish to use.
# Android orb docs are available here:
  android: circleci/android@1.0
      # This job uses the Android machine image by default
      - android/run-ui-tests:
          # Use pre-steps and post-steps if necessary
          # to execute custom steps before and afer any of the built-in steps
          system-image: system-images;android-29;default;x86

As per above, using the Android orb will simplify your configuration; you can compare and contrast examples of different sizes here.

Sample configuration for unit tests

For convenience, CircleCI provides a set of Docker images for building Android apps. These pre-built images are available in the CircleCI org on Docker Hub. The source code and Dockerfiles for these images are available in this GitHub repository.

The CircleCI Android image is based on the openjdk:11-jdk official Docker image, which is based on buildpack-deps. The base OS is Debian Jessie, and builds run as the circleci user, which has full access to passwordless sudo.

The following example demonstrates using an Android docker image rather than the Android machine image.

version: 2
    working_directory: ~/code
      - image: cimg/android:2021.10.2
          username: mydockerhub-user
          password: $DOCKERHUB_PASSWORD  # context / project UI env-var reference
      JVM_OPTS: -Xmx3200m
      - checkout
      - restore_cache:
          key: jars-{{ checksum "build.gradle" }}-{{ checksum  "app/build.gradle" }}
#      - run:
#         name: Chmod permissions #if permission for Gradlew Dependencies fail, use this.
#         command: sudo chmod +x ./gradlew
      - run:
          name: Download Dependencies
          command: ./gradlew androidDependencies
      - save_cache:
            - ~/.gradle
          key: jars-{{ checksum "build.gradle" }}-{{ checksum  "app/build.gradle" }}
      - run:
          name: Run Tests
          command: ./gradlew lint test
      - store_artifacts: # for display in Artifacts:
          path: app/build/reports
          destination: reports
      - store_test_results: # for display in Test Summary:
          path: app/build/test-results
      # See https:circleci/docs/deployment-overview#next-steps document for links to target configuration examples

React Native projects

React Native projects can be built on CircleCI using Linux, Android and macOS capabilities. Please check out this example React Native application on GitHub for a full example of a React Native project.

Testing with Firebase Test Lab

Note:: While this portion of the document walks through using a third party tool for testing, CircleCI recommends using the Android machine image for running emulator tests.

To use Firebase Test Lab with CircleCI, first complete the following steps.

  1. Create a Firebase project. Follow the instructions in the Firebase documentation.

  2. Install and authorize the Google Cloud SDK. Follow the instructions in the Authorizing the Google Cloud SDK document.

    Note: Instead of google/cloud-sdk, consider using an Android convenience image, which includes gcloud and Android-specific tools.

  3. Enable required APIs. Using the service account you created, log into Google and go to the Google Developers Console API Library page. Enable the Google Cloud Testing API and the Cloud Tool Results API by typing their names into the search box at the top of the console and clicking Enable API.

In your .circleci/config.yml file, add the following run steps.

  1. Build the debug APK and test APK. Use Gradle to build two APKs. To improve build performance, consider disabling pre-dexing.

  2. Store the service account. Store the service account you created in a local JSON file.

  3. Authorize gcloud. Authorize the gcloud tool and set the default project.

  4. Use gcloud to test with Firebase Test Lab. Adjust the paths to the APK files to correspond to your project.

  5. Install crcmod and use gsutil to copy test results data. crcmod is required to use gsutil. Use gsutil to download the newest files in the bucket to the CircleCI artifacts folder. Be sure to replace BUCKET_NAME and OBJECT_NAME with project-specific names.

version: 2
      - image: cimg/android:2021.10.2  # gcloud is baked into this image
          username: mydockerhub-user
          password: $DOCKERHUB_PASSWORD  # context / project UI env-var reference
      - run:
          name: Build debug APK and release APK
          command: |
            ./gradlew :app:assembleDebug
            ./gradlew :app:assembleDebugAndroidTest
      - run:
          name: Store Google Service Account
          command: echo $GCLOUD_SERVICE_KEY > ${HOME}/gcloud-service-key.json
      - run:
          name: Authorize gcloud and set config defaults
          command: |
            sudo gcloud auth activate-service-account --key-file=${HOME}/gcloud-service-key.json
            sudo gcloud --quiet config set project ${GOOGLE_PROJECT_ID}
      - run:
          name: Test with Firebase Test Lab
          command: >
            sudo gcloud firebase test android run \
              --app <local_server_path>/<app_apk>.apk \
              --test <local_server_path>/<app_test_apk>.apk \
              --results-bucket cloud-test-${GOOGLE_PROJECT_ID}
      - run:
          name: Install gsutil dependency and copy test results data
          command: |
            sudo pip install -U crcmod
            sudo gsutil -m cp -r -U `sudo gsutil ls gs://[BUCKET_NAME]/[OBJECT_NAME] | tail -1` ${CIRCLE_ARTIFACTS}/ | true

For more details on using gcloud to run Firebase, see the official documentation.


See the Deployment overview document for links to various target configuration examples.


Handling out of memory errors

You might run into out of memory (oom) errors with your build. To get acquainted with the basics of customizing the JVM’s memory usage, consider reading the Debugging Java OOM errors document.

If you are using Robolectric for testing you may need to make tweaks to gradle’s use of memory. When the gradle vm is forked for tests it does not receive previously customized JVM memory parameters. You will need to supply Gradle with additional JVM heap for tests in your build.gradle file by adding android.testOptions.unitTests.all { maxHeapSize = "1024m" }. You can also add all { maxHeapSize = "1024m" } to your existing Android config block, which could look like so after the addition:

android {
    testOptions {
        unitTests {
            // Any other configurations

            all {
                maxHeapSize = "1024m"

If you are still running into OOM issues you can also limit the max workers for gradle: ./gradlew test --max-workers 4

Disabling pre-dexing to improve build performance

Pre-dexing dependencies has no benefit on CircleCI. To disable pre-dexing, refer to this blog post.

By default, the Gradle Android plugin pre-dexes dependencies. Pre-dexing speeds up development by converting Java bytecode into Android bytecode, allowing incremental dexing as you change code. CircleCI runs clean builds, so pre-dexing actually increases compilation time and may also increase memory usage.

Deploying to Google Play Store

There are a few third-party solutions for deploying to the Play Store from your CI build. Gradle Play Publisher enables you to upload an App Bundle/APK as well as app metadata. It’s also possible to use Fastlane with Android.

Help make this document better

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