AWS CDK Docker Image Assets

---

End-of-Support

AWS CDK v1 has reached End-of-Support on 2023-06-01. This package is no longer being updated, and users should migrate to AWS CDK v2.

For more information on how to migrate, see the Migrating to AWS CDK v2 guide.

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 Amazon Elastic Container Registry (ECR) by the CDK toolkit and/or your app’s CI/CD pipeline, and can be naturally referenced in your CDK app.

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 Amazon 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. It is recommended to skip hashing of buildArgs for values that can change between different machines to maintain a consistent asset hash.

from aws_cdk.aws_ecr_assets import DockerImageAsset


asset = DockerImageAsset(self, "MyBuildImage",
    directory=path.join(__dirname, "my-image"),
    build_args={
        "HTTP_PROXY": "http://10.20.30.2:1234"
    },
    invalidation=DockerImageAssetInvalidationOptions(
        build_args=False
    )
)

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

from aws_cdk.aws_ecr_assets import DockerImageAsset


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

You can optionally pass networking mode to the docker build command by specifying the networkMode property:

from aws_cdk.aws_ecr_assets import DockerImageAsset, NetworkMode


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

You can optionally pass an alternate platform to the docker build command by specifying the platform property:

from aws_cdk.aws_ecr_assets import DockerImageAsset, Platform


asset = DockerImageAsset(self, "MyBuildImage",
    directory=path.join(__dirname, "my-image"),
    platform=Platform.LINUX_ARM64
)

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.

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 Amazon 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:

// This example available in TypeScript only

import { DockerImageAsset } from '@aws-cdk/aws-ecr-assets';
import * as ecrdeploy from 'cdk-ecr-deployment';

const image = new DockerImageAsset(this, 'CDKDockerImage', {
  directory: path.join(__dirname, 'docker'),
});

new ecrdeploy.ECRDeployment(this, 'DeployDockerImage', {
  src: new ecrdeploy.DockerImageName(image.imageUri),
  dest: new ecrdeploy.DockerImageName(`${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”.