Google Cloud Builders

 Cloud builders are container images with common languages and tools installed in them. You can configure Cloud Build to run a specific command within the context of these builders.

This page describes the types of builders that you can use with Cloud Build.

Publicly available images

Cloud Build enables you to use any publicly available image to execute your tasks. To use an image, specify the image URL in the name field in your config file. Use the args field to specify commands that you want to run within the image. The args field of a build step takes a list of arguments and passes them to the image referenced by the name field.

Note: When you pull a public container image from Docker Hub to use in your build config file, Cloud Build automatically checks the caching proxy mirror.gcr.io for a cached copy of the container image. If a cached copy is unavailable, Cloud Build pulls your requested image from Docker Hub and the caching proxy might cache the image for future use. For more information, see Pulling cached images.

The following code snippet shows how to use the public ubuntu image from Docker Hub and execute a command within that image:

steps:
- name: 'ubuntu'
  args: ['echo', 'hello world']

Here's another example code snippet that uses the image for Black Duck open source scanner for Cloud Build from Google Cloud console Launcher:

steps:
- name: launcher.gcr.io/blackduck-public/blackducksoftware-containerbuilder-scanner
  ...

For more examples on how to use publicly available images from Docker Hub for your tasks, see Building Node.js applications and Building Go applications.

Note: Cloud Build runs its build steps in a Docker container. To use an image from Docker Hub, just specify the name of the image, such as ubuntu. To use an image from other registries, specify the full registry path of the image, such as gcr.io/cloud-builders/gcloud.

Supported builder images provided by Cloud Build

Cloud Build provides and maintains pre-built images that you can reference in your config file to execute your tasks. You can find these pre-built images in the following location:

gcr.io/cloud-builders/...

The source code for these builders is available in the cloud builders GitHub repository.

For examples on how to use supported pre-built images, see Building container images and Deploying to Cloud Run.

The following table lists some examples of supported builder images:

Builder	Name	Example
bazel	gcr.io/cloud-builders/bazel	bazel example
docker	gcr.io/cloud-builders/docker	docker example
git	gcr.io/cloud-builders/git	git example
gcloud	gcr.io/cloud-builders/gcloud	gcloud example
gke-deploy	gcr.io/cloud-builders/gke-deploy	gke-deploy example
gradle	gcr.io/cloud-builders/gradle	gradle example
maven	gcr.io/cloud-builders/mvn	maven example
The complete list of supported builders for Cloud Build.

Community-contributed builders

The Cloud Build developer community provides open-source builders that you can use to execute your tasks. Pre-built images are not available for these builders; to use these builders, download the source code from the cloud builders community GitHub repository and then build the image. For an example on how to build a community-contributed builder and then use it for your tasks, see Building VM images using Packer.

The following table lists some examples of community-contributed builders:

Builder	Description
docker-compose	Runs integration tests on docker images.
remote-builder	Executes your build step on a configurable Compute Engine VM.
packer	Automates the creation of machine images using Packer
helm	Manages Kubernetes packages using Helm.
pack	Executes your build step using the specified Cloud Native Buildpack.
kaniko	Executes your build step using kaniko.
The complete list of community-contributed builders for Cloud Build.

Community-contributed builders are maintained by the open-source community at cloud builders community. Cloud Build does not officially maintain these builders. For information on contributing to a builder, see the cloud builders community GitHub page.

Writing your own custom builder

You can create your own custom builder for use in your builds. A custom builder is a container image that the Cloud Build pulls and runs with your source. Your custom builder can execute any script or binary inside the container; as such it can do anything a container can do. For instructions on creating a custom builder, see Creating custom build steps.