AWS CDK Docker Image Assets

---

cdk-constructs: Stable


This module allows bundling Docker images as assets.

Images from Dockerfile

Images are built from a local Docker context directory (with a Dockerfile), uploaded to ECR by the CDK toolkit and/or your app’s CI-CD pipeline, and can be naturally referenced in your CDK app.

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
from aws_cdk.aws_ecr_assets import DockerImageAsset

asset = DockerImageAsset(self, "MyBuildImage",
    directory=path.join(__dirname, "my-image")
)

The directory my-image must include a Dockerfile.

This will instruct the toolkit to build a Docker image from my-image, push it to an AWS ECR repository and wire the name of the repository as CloudFormation parameters to your stack.

By default, all files in the given directory will be copied into the docker build context. If there is a large directory that you know you definitely don’t need in the build context you can improve the performance by adding the names of files and directories to ignore to a file called .dockerignore, or pass them via the exclude property. If both are available, the patterns found in exclude are appended to the patterns found in .dockerignore.

The ignoreMode property controls how the set of ignore patterns is interpreted. The recommended setting for Docker image assets is IgnoreMode.DOCKER. If the context flag @aws-cdk/aws-ecr-assets:dockerIgnoreSupport is set to true in your cdk.json (this is by default for new projects, but must be set manually for old projects) then IgnoreMode.DOCKER is the default and you don’t need to configure it on the asset itself.

Use asset.imageUri to reference the image. It includes both the ECR image URL and tag.

You can optionally pass build args to the docker build command by specifying the buildArgs property:

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
asset = DockerImageAsset(self, "MyBuildImage",
    directory=path.join(__dirname, "my-image"),
    build_args={
        "HTTP_PROXY": "http://10.20.30.2:1234"
    }
)

You can optionally pass a target to the docker build command by specifying the target property:

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
asset = DockerImageAsset(self, "MyBuildImage",
    directory=path.join(__dirname, "my-image"),
    target="a-target"
)

Images from Tarball

Images are loaded from a local tarball, uploaded to ECR by the CDK toolkit and/or your app’s CI-CD pipeline, and can be naturally referenced in your CDK app.

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
from aws_cdk.aws_ecr_assets import TarballImageAsset

asset = TarballImageAsset(self, "MyBuildImage",
    tarball_file="local-image.tar"
)

This will instruct the toolkit to add the tarball as a file asset. During deployment it will load the container image from local-image.tar, push it to an AWS ECR repository and wire the name of the repository as CloudFormation parameters to your stack.

Publishing images to ECR repositories

DockerImageAsset is designed for seamless build & consumption of image assets by CDK code deployed to multiple environments through the CDK CLI or through CI/CD workflows. To that end, the ECR repository behind this construct is controlled by the AWS CDK. The mechanics of where these images are published and how are intentionally kept as an implementation detail, and the construct does not support customizations such as specifying the ECR repository name or tags.

If you are looking for a way to publish image assets to an ECR repository in your control, you should consider using cdklabs/cdk-ecr-deployment, which is able to replicate an image asset from the CDK-controlled ECR repository to a repository of your choice.

Here an example from the cdklabs/cdk-ecr-deployment project:

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
import cdk_ecr_deployment as ecrdeploy


image = DockerImageAsset(self, "CDKDockerImage",
    directory=path.join(__dirname, "docker")
)

ecrdeploy.ECRDeployment(self, "DeployDockerImage",
    src=ecrdeploy.DockerImageName(image.image_uri),
    dest=ecrdeploy.DockerImageName(f"{cdk.Aws.ACCOUNT_ID}.dkr.ecr.us-west-2.amazonaws.com/test:nginx")
)

⚠️ Please note that this is a 3rd-party construct library and is not officially supported by AWS. You are welcome to +1 this GitHub issue if you would like to see native support for this use-case in the AWS CDK.

Pull Permissions

Depending on the consumer of your image asset, you will need to make sure the principal has permissions to pull the image.

In most cases, you should use the asset.repository.grantPull(principal) method. This will modify the IAM policy of the principal to allow it to pull images from this repository.

If the pulling principal is not in the same account or is an AWS service that doesn’t assume a role in your account (e.g. AWS CodeBuild), pull permissions must be granted on the resource policy (and not on the principal’s policy). To do that, you can use asset.repository.addToResourcePolicy(statement) to grant the desired principal the following permissions: “ecr:GetDownloadUrlForLayer”, “ecr:BatchGetImage” and “ecr:BatchCheckLayerAvailability”.