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Building Go applications

This page explains how to use Cloud Build to build, test, and deploy Go applications. If you're new to Cloud Build, read the quickstarts and the build configuration overview first.

Before you begin

The instructions on this page assume that you are familiar with Go. In addition:

  • Enable the Cloud Build, Cloud Run, and Artifact Registry APIs.

    Enable the APIs

  • To run the gcloud commands on this page, install Cloud SDK.
  • Have your Go project handy.
  • If you want to containerize your Go app using Cloud Build, you'll need a Dockerfile along with your source code.
  • If you want to store the built container in Artifact Registry, create a Docker repository in Artifact Registry.
  • If you want to store test logs in Cloud Storage, create a bucket in Cloud Storage.

Required IAM permissions

For instructions on granting these roles see Granting a role using the IAM page.

Configuring Go builds

The public golang image from Docker Hub supports building using Go modules. Using this image as a build step in your Cloud Build config file enables you to invoke go commands within the image. Arguments passed to this build step are passed to the golang tool directly, allowing you to run any go command in this image.

This section walks through an example build config file for a Go app. It has build steps to build the app, add unit tests, and after the tests pass, containerize, and deploy the app.

To build your Go application:

  1. In your project root directory, create Cloud Build config file named cloudbuild.yaml.

  2. Build and test: If you've defined unit tests in your application, you can configure Cloud Build to run the tests by adding the following fields in a build step:

    • name: Set the value of this field to golang to use the golang image from Docker Hub for your task.
    • entrypoint: Set the value of this field to /bin/bash. This enables you to run multi-line bash commands directly from the build step.

    • args: The args field of a build step takes a list of arguments and passes them to the image referenced by the name field. In the following example, the args field takes the arguments for:

      • Running the test log formatter to download the test log output.
      • Printing the log output.
      • Saving test results in sponge.log.
      • Outputting the results in sponge.log to a JUNIT XML file. The name of the JUNIT XML file is constructed using the short version of the commit ID associated with your build. A subsequent build step will save the logs in this file to Cloud Storage.
      steps:
  # Run tests and save to file
  - name: golang
    entrypoint: /bin/bash
    args: 
      - -c
      - |
        go get -u github.com/jstemmer/go-junit-report
        2>&1 go test -timeout 1m -v ./... | tee sponge.log
        /go/bin/go-junit-report -set-exit-code < sponge.log > ${SHORT_SHA}_test_log.xml

  3. Containerize the app: After adding the build step to ensure that the tests have passed, you can build the application. Cloud Build provides a pre-built Docker image that you can use to containerize your Go application. To containerize your app, add the following fields in a build step:

    • name: Set the value of this field to gcr.io/cloud-builders/docker to use the prebuilt docker image from Container Registry for your task.
    • args: Add the arguments for the docker build command as values for this field.

    The following build step builds the image myimage and tags it with the short version of your commit ID. The build step uses substitutions for project ID, repository name, and short SHA values therefore these values are automatically substituted at build time. Note that you will need to create or have an existing Docker repository in Artifact Registry to store the image.

    # Docker Build
- name: 'gcr.io/cloud-builders/docker'
  args: ['build', '-t', 
         'us-central1-docker.pkg.dev/$PROJECT_ID/$_REPO_NAME/myimage:$SHORT_SHA', '.']

  4. Push the container to Artifact Registry: You can store the built container in Artifact Registry, which is a Google Cloud service that you can use to store, manage, and secure build artifacts. To do this, you'll need to have an existing Docker repository in Artifact Registry. To configure Cloud Build to store the image in an Artifact Registry Docker repository, add a build step with the following fields:

    • name: Set the value of this field to gcr.io/cloud-builders/docker to use the official docker builder image from Container Registry for your task.
    • args: Add the arguments for the docker push command as values of this field. For the destination URL, enter the Artifact Registry Docker repository where you want to store the image.

    The following build step pushes the image that you built in the previous step to Artifact Registry:

    # Docker push to Google Artifact Registry
- name: 'gcr.io/cloud-builders/docker'
  args: ['push', 'us-central1-docker.pkg.dev/$PROJECT_ID/$_REPO_NAME/myimage:$SHORT_SHA']

  5. Deploy the container to Cloud Run: To deploy the image on Cloud Run, add a build step with the following fields:

    • name: Set the value of this field to google/cloud-sdk to use the Cloud SDK image to invoke the gcloud command to deploy the image on Cloud Run.
    • args: Add the arguments for the gcloud run deploy command as the values of this field.

    The following build step deploys the previously built image to Cloud Run:

    # Deploy to Cloud Run
- name: 'gcr.io/cloud-builders/gcloud'
  args: ['run', 'deploy', 'helloworld', 
         '--image=us-central1-docker.pkg.dev/$PROJECT_ID/$_REPO_NAME/myimage:$SHORT_SHA', 
         '--region', 'us-central1', '--platform', 'managed']

  6. Save test logs to Cloud Storage: You can configure Cloud Build to store any test logs in Cloud Storage by specifying an existing bucket location and path to the test logs.

    The following build step stores the test logs that you saved in the JUNIT XML file to a Cloud Storage bucket:

    # Save test logs to Google Cloud Storage
artifacts:
  objects:
    location: gs://$_BUCKET_NAME/
    paths:
      - ${SHORT_SHA}_test_log.xml

    The following snippet shows the complete build config file for the all the steps described above:

    steps:
  # Run tests and save to file
  - name: golang
    entrypoint: /bin/bash
    args: 
      - -c
      - |
        go get -u github.com/jstemmer/go-junit-report
        2>&1 go test -timeout 1m -v ./... | tee sponge.log
        /go/bin/go-junit-report -set-exit-code < sponge.log > ${SHORT_SHA}_test_log.xml

  # Docker Build
  - name: 'gcr.io/cloud-builders/docker'
    args: ['build', '-t', 
           'us-central1-docker.pkg.dev/$PROJECT_ID/$_REPO_NAME/myimage:$SHORT_SHA', '.']

  # Docker push to Google Artifact Registry
  - name: 'gcr.io/cloud-builders/docker'
    args: ['push', 'us-central1-docker.pkg.dev/$PROJECT_ID/$_REPO_NAME/myimage:$SHORT_SHA']

  # Deploy to Cloud Run
  - name: 'gcr.io/cloud-builders/gcloud'
    args: ['run', 'deploy', 'helloworld', 
           '--image=us-central1-docker.pkg.dev/$PROJECT_ID/$_REPO_NAME/myimage:$SHORT_SHA', 
           '--region', 'us-central1', '--platform', 'managed']

# Save test logs to Google Cloud Storage
artifacts:
  objects:
    location: gs://$_BUCKET_NAME/
    paths:
      - ${SHORT_SHA}_test_log.xml
# Store images in Google Artifact Registry
images:
  - us-central1-docker.pkg.dev/$PROJECT_ID/$_REPO_NAME/myimage:$SHORT_SHA

  7. Start the build using the gcloud tool or build triggers. You'll must specify the Artifact Registry repository name when starting the build.

    To specify the Artifact Registry repository when starting the build using the gcloud tool:

    gcloud builds submit --config=cloudbuild.yaml \
    --substitutions=_REPO_NAME="REPO_NAME"

    Replace REPO_NAME with the name of your Artifact Registry repository.

    To specify the Artifact Registry repository when building with build triggers, specify the the name of your Artifact Registry repository in the Substitution variables field when creating the build trigger.

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