Continuous Integration & Delivery (CI/CD) for Android

This is a getting started guide to build native Android apps with Codemagic CI/CD.

Written by Souvik Biswas

Learn from this article how to configure the codemagic.yaml file for building Native Android projects on Codemagic CI/CD. Since the introduction of the codemagic.yaml file, it has been a lot easier to keep your build configurations more organized and manage all your workflows with just a single file. This file can be committed to version control and gets automatically detected during build from the Codemagic UI.

Though Codemagic does not come with support for building native Android and iOS apps directly from the UI, you can easily configure the codemagic.yaml file for building native apps. In this article, you will learn how to configure the codemagic.yaml file for building native Android projects on Codemagic.

It is recommended to go through the article for better understanding but if you already have experience with using codemagic.yaml file, you can get the YAML template for a native Android project here.

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Now we will go through the steps to show how easy it is to set up CI/CD for your native Android app using Codemagic CI/CD.

Android continuous integration: Getting started with Codemagic

Make sure that your native Android project is uploaded to a code hosting platform (like GitHub, Bitbucket or GitLab) using a version control system.

1. Log in to Codemagic.

2. In the Applications overview, search for your project and click Set up build.

3. Select Android App as the starter workflow.

   

4. You can download the YAML template for native Android by clicking on the download button.

   

5. Now, open the codemagic.yaml file using any code editor. The YAML file contents will look like this:

# Workflow setup for building Native Android project
workflows:
  android-app: # workflow ID
    name: Android app # workflow name
    scripts:
      - ./gradlew assembleDebug
    artifacts:
      - build/outputs/**/**/*.apk

Android workflow and a default YAML file

You will see that a default workflow ID and workflow name is specified, but you can change them however you wish.

The default Android workflow specified in the codemagic.yaml file is very simple and will help you get started if you want to generate a debug build of your Android app.

Deep dive into YAML

Let’s take a closer look at the codemagic.yaml file and understand the real power of it.

Scripts

In order to generate a debug build, you will need a debug.keystore file. The following is the code for generating the file:

keytool -genkeypair \
-alias androiddebugkey \
-keypass android \
-keystore ~/.android/debug.keystore \
-storepass android \
-dname 'CN=Android Debug,O=Android,C=US' \
-keyalg 'RSA' \
-keysize 2048 \
-validity 10000

Running local unit tests:

./gradlew test

Running instrumented unit tests:

./gradlew connectedAndroidTest

You will also need to start up an Android emulator in order to run the instrumented unit tests. Add the following command:

emulator -avd emulator > /dev/null 2>&1 &

The & is used in the end of this command to run it in the background, otherwise the emulator command blocks the terminal and prevents any further commands from execution. > /dev/null 2>&1 is used to ignore all outputs of this command.

TIPS: It is better to add this command at the beginning of the script, as the emulator takes some time to start up.

Building the app in debug mode:

./gradlew assembleDebug

Artifacts

You can get the generated .apk file by adding its path under the artifacts. Normally, the path is like this:

artifacts:
  - app/build/**/outputs/**/*.apk

Publishing

To get a report of the build along with the generated artifacts in your email, specify the following:

publishing:
  email:
    recipients:
      - name@example.com # enter your email id here

For more information about publishing, refer to this link.

Setting up your Android project for a release build

First of all, you have to set up code signing for generating release build.

Generating a keystore

If you don’t already have a keystore created, you can use the following command from your Terminal to generate one.

keytool -genkey -v -keystore keystore_name.keystore -alias alias_name -keyalg RSA -keysize 2048 -validity 10000

Configuring your project

Follow the steps below to prepare your project for a release build:

1. Open your project using Android Studio.

2. Switch to the Project View.

3. Inside the root project folder, create a new file called key.properties.

4. Add the following to this file:

   storePassword=<enter keystore password>
   keyPassword=<enter key alias password>
   keyAlias=<enter key alias name>
   storeFile=<enter .keystore file path>
   

   Replace the angle brackets and its content with the appropriate values.

5. Save the file and add it to .gitignore, so that you do not commit this file by mistake.

6. Now, switch to the Android View, and go to the app level build.gradle.

7. Add the following to this file:

   def keystorePropertiesFile= rootProject.file("key.properties")
   def keystoreProperties = new Properties()
   keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
   
   // Add above this line
   android {
   

8. Add the signingConfigs:

   signingConfigs {
       config {
           keyAlias keystoreProperties['keyAlias']
           keyPassword keystoreProperties['keyPassword']
           storeFile file(keystoreProperties['storeFile'])
           storePassword keystoreProperties['storePassword']
       }
   }
   

9. Inside buildTypes release, add the following:

   buildTypes {
       release {
           //...
           signingConfig signingConfigs.config
       }
   }
   

Modifying YAML for code signing

You will need the keystore file to sign your build. To get access to it, you will also need the key.properties file.

As you have added the key.properties file to .gitignore, it won’t be available during build on Codemagic. So you can encrypt all the sensitive information and add it to the codemagic.yaml file for generating the key.properties file which can be used in turn to unlock the .keystore file.

Follow the steps below to encrypt your sensitive information:

• Go to your project Settings on Codemagic.

• Click Encrypt environment variables.

• You can drag and drop files here or enter the value to generate an encrypted version of them.

  

Now, create a new workflow called release-workflow for the release build and add the following:

release-workflow:
  name: Native Android
  max_build_duration: 60
  environment:
    vars:
      CM_KEYSTORE: # Add encrypted keystore file
      CM_KEYSTORE_PASSWORD: # Add encrypted keystore password
      CM_KEY_ALIAS_PASSWORD: # Add encrypted alias password
      CM_KEY_ALIAS_USERNAME: # Add alias name
  scripts: # Add the build configurations here
  artifacts:
    - app/build/**/outputs/**/*.apk
  publishing:
    email:
      recipients:
        - sbis1999@gmail.com

Let’s define the build script now.

First of all, you have to decrypt the .keystore file and generate the key.properties file.

scripts:
  # ...
  - |
    # set up release keystore
    echo $CM_KEYSTORE | base64 --decode > /tmp/keystore.keystore
    cat >> "$FCI_BUILD_DIR/key.properties" <<EOF
    storePassword=$CM_KEYSTORE_PASSWORD
    keyPassword=$CM_KEY_ALIAS_PASSWORD
    keyAlias=$CM_KEY_ALIAS_USERNAME
    storeFile=/tmp/keystore.keystore
    EOF    

Then, you can add tests as usual and use the following command for generating a release build:

./gradlew assembleRelease

You have successfully completed the setup for generating a release build of your app.

Building an Android project on Codemagic

Before starting a build on Codemagic, make sure that you have the codemagic.yaml file committed to the version control system.

Follow the steps below to start a build:

1. In the Applications dashboard, click Finish build setup.

2. Click Check for configuration file.

   

3. Then, click Start your first build.

   

4. Select the workflow from the YAML file and click Start new build.

   

This will start a new build for your native Android project.

Awesome! Your first Android build with Codemagic CI/CD is complete! Congratulations!

Conclusion

Although Codemagic started as an official CI/CD solution dedicated just for Flutter apps, it now welcomes all mobile projects to the fastest CI/CD. You can easily build, test, and publish your Android, iOS, React Native and Flutter apps with Codemagic CI/CD.

As you can see, building native Android apps on Codemagic using the codemagic.yaml file is really simple. There is also an added advantage, as YAML makes it a lot easier to manage your workflows and keep your build configurations more organized. Also, it gets automatically detected from the version control system when starting any build on Codemagic.

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Useful links and references

• Official YAML Documentation

• More information about Android code signing is available here.

• The GitHub repo of the sample project is here.

Souvik Biswas is a passionate Mobile App Developer (Android and Flutter). He has worked on a number of mobile apps throughout his journey. Loves open source contribution on GitHub. He is currently pursuing a B.Tech degree in Computer Science and Engineering from Indian Institute of Information Technology Kalyani. He also writes Flutter articles on Medium - Flutter Community.