(@aws-cdk/aws-ecr-assets): DockerImageAsset - support `--build-context` flag

[BwL1289]

Describe the feature

We use CDK Pipelines to deploy our infrastructure to dev, staging, and prod accounts.

When we are building dockerfiles using DockerImageAssets, if there are any files/directories the dockerfile needs while being built, we currently have to copy them over any files/directories to the directory where the dockerfile is being built. This is cumbersome and error prone.

Docker now supports (since 2022) the ability to specify multiple build contexts via the --build-context flag.

It would be great to add --build-context to the flags supported here.

Here's an example:

from aws_cdk import aws_ecr_assets as ecr_assets

ecr_docker_image_asset = ecr_assets.DockerImageAsset(
            self,
            "EcrDockerImageAsset",
            directory=<dir>,
            file="Dockerfile",
            build_args=<build_args>,
            build_contexts=["example_build_context_1", "example_build_context_2", ...]
)

Then, we can use the following in the dockerfile like so:

COPY --from=example_build_context_1 ...

Use Case

With --build-context now supported, It's unnecessary to copy any additional files/directories into the build context where you are building your image.

Proposed Solution

Support the --build-context flag.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.158.0

Environment details (OS name and version, etc.)

macOS Sonoma 14.5, AWS CodeBuild

[khushail]

Hi @BwL1289 , thanks for reaching out.

I see this request raised in the past - #3342 but few workaround were suggested - #3342 (comment) as in favor of not implementing this flag. For now, you could use this directory construct prop to mention the path.

However given the context of usage and support, this would be good to have. So I am marking this as P3 which means it won't be immediately addressed by the team but is open for team as well as community contribution.