Build, test, and containerize Java applications

This page explains how to use Cloud Build to build, test, and containerize Java-based applications, upload your container images to Artifact Registry, generate build provenance.

Before you begin

Using the maven or gradle image

You can configure Cloud Build to build Java applications using the maven image or the gradle image from Docker Hub.

To execute your tasks in the maven or gradle image, specify the URL of the image and the tagged version of the image in the name field of your build config file. If you don't specify the image tag, Cloud Build uses the latest image by default. Cloud Build starts the image specified in name by using the image's default entrypoint. To override the default entrypoint and to invoke maven or gradle as an entrypoint, specify mvn or gradle in the entrypoint field.

The following build config file specifies the entrypoint for the maven or gradle image and prints the build tool version:

maven 

  steps:
  - name: maven:3.3-jdk-8
    entrypoint: mvn
    args: ['--version']

gradle 

  steps:
  - name: gradle:5.6.2-jdk8
    entrypoint: gradle
    args: ['--version']

Configuring Java builds

  1. In your project root directory, create a build config file named cloudbuild.yaml.

  2. Run tests: maven and gradle provide maven test and gradle test, which downloads dependencies, builds the applications, and runs any tests specified in your source code. The args field of a build step takes a list of arguments and passes them to the image referenced by the name field.

    In your build config file, add test to the args field to invoke test within maven and gradle:

    maven 

     steps:
 - name: maven:3.3-jdk-8
   entrypoint: mvn
   args: ['test']

    gradle 

     steps:
 - name: gradle:5.6.2-jdk8
   entrypoint: gradle
   args: ['test']

  3. Package application: To package your application into a JAR file for your maven image, specify the package command in the args field. The package command builds a JAR file in /workspace/target/.

    To package your application into a JAR file for your gradle image, specify the assemble command in the args field. The assemble command builds a JAR file in workspace/build/libs.

    The following build step packages your Java application:

    maven 

     steps:
 - name: maven:3.3-jdk-8
   entrypoint: mvn
   args: ['package','-Dmaven.test.skip=true']

    gradle 

    steps:
- name: gradle:5.6.2-jdk8
  entrypoint: gradle
  args: ['assemble']

  4. Containerize application: Cloud Build provides a pre-built Docker image that you can use to containerize your Java application. To containerize your Java application, in your build config file:

    • Add a name field and specify the pre-built Docker image at gcr.io/cloud-builders/docker.
    • Add an args field and specify the build arguments, including the name of the container image to build, and the path to your build artifact.
    • Add an images field to push the built container image to Artifact Registry and generate build provenance information. If you do not use the images field, Cloud Build will not record provenance information. For example, if you use a docker push build step to upload images to Artifact Registry, your build will not have associated provenance information.

    The following build step containerizes your application and pushes your container image to Artifact Registry, and generates build provenance information.

    maven 

    steps:
- name: gcr.io/cloud-builders/docker
  args: ['build', '-t', 'location-docker.pkg.dev/project-id/repository/image', '--build-arg=JAR_FILE=target/build-artifact', '.']
images: ['location-docker.pkg.dev/project-id/repository/image']

    gradle 

    steps:
- name: gcr.io/cloud-builders/docker
  args: ['build', '-t', 'location-docker.pkg.dev/project-id/repository/image', '--build-arg=JAR_FILE=build/libs/build-artifact', '.']
images: ['location-docker.pkg.dev/project-id/repository/image']

    Where:

    • location: the regional or multi-regional location for your repository.
    • project-id: the id of your Google Cloud project.
    • repository: the name of your repository Artifact Registry.
    • image: the name of your container image.
    • build-artifact: the name of your JAR file created from your build step.

  5. Optional: Enable provenance for regional builds

    If you are using a regional build, add the requestedVerifyOption field in the options in your build config file. Set the value to VERIFIED to enable provenance metadata generation. If you don't add requestedVerifyOption: VERIFIED, Cloud Build generates provenance for global builds only.

    options:
  requestedVerifyOption: VERIFIED

  6. Start your build: When you have your build config file ready, start your build by entering the following command in your terminal:

    gcloud builds submit --region=REGION --config config-file-path source-directory

    Where:

    • config-file-path: the path to your build config file. In this example, the build config file is named cloudbuild.yaml.
    • source-directory: the path or URL to your source code.
    • REGION: one of the supported build regions.

    If you don't specify a config-file-path and source-directory in the gcloud builds submit command, Cloud Build assumes that the config file and the source code are in the current working directory.

    Once your build completes, you can view repository details in Artifact Registry.

    You can also view build provenance metadata and validate provenance to help protect your software supply chain.

Code examples

Here are some example repositories you can use to build Java apps, each of which contain a sample application and a build config file to build and test that application:

  • maven-example: A Java app and an example build config file to build and test the app with mvn.
  • gradle-example: A Java app and an example build config file to build and test the app with gradle.

What's next