Feature Request: Pass build params to docker/finch CLI

Hey

I have a SAM application with multiple AWS lambda functions, that are image based.

Right now we run our CICD pipeline of a Jenkins server that runs on EC2.
All the intermediate docker layers are caches on the instance itself.

We are moving our Jenkins stack (workers and controller) from running on EC2 to EKS, so the layers won't be cached.
There is a solution for this with docker buildkit:
--cache-to and --cache-from.

What is a sutible solution for this when using AWS SAM?

In #8661, I've added the framework for using docker buildkit. I believe once this is merged, it should be possible to use the --cache-to and --cache-from options with BuildKit via the DockerBuildArgs section in the Metadata of the template:

Metadata:
  # ...
  DockerBuildArgs:
    CACHE_TO: !Ref CacheLocation

I haven't thought too much about using other methods to achieve this, but I think this will work with your existing flow once merged.

@royassis

Hi @royassis, #8661 will be available to use in the next release, coming later this week or early next week. Thank you for your patience!

@royassis

Hi @royassis, #8661 will be available to use in the next release, coming later this week or early next week. Thank you for your patience!

I'm very excited. Thank you.

@seshubaws

Hey @seshubaws

I tried to use cache-from and cache-to like so:

Metadata:
  # ...
  DockerBuildArgs:
    CACHE_TO: !Ref CacheLocation

When running sam build --use-buildkit it indeed finishes the build, but it seems that the layers might not be cached to ECR as I expected, I don't see any new images in my cache repo, after running sam build.

When investigating with kiro, it mentioned this, so it might be related:

But looking at the actual code in CLIBuildClient.build_image, all DockerBuildArgs entries are passed as --build-arg:
if buildargs:
    for k, v in buildargs.items():
        cmd.extend(["--build-arg", f"{k}={v}"])
So CACHE_TO and CACHE_FROM in DockerBuildArgs become --build-arg CACHE_TO=... and --build-arg CACHE_FROM=... — not --cache-to and --cache-from.

@royassis

Hi @royassis, thanks for raising this! It seems we will have to implement a workaround for this so that the correct args get passed to DockerCLI.

Hi @royassis, thanks for raising this! It seems we will have to implement a workaround for this so that the correct args get passed to DockerCLI.

Should we open a feature request?

@royassis

Hello @royassis, I previously had misunderstood the difference between the build args that are passed to the Dockerfile and the build params that would be passed to the CLI.

That being said, I'm opening up a new PR to give the functionality that you're asking for: #8913. It's still in draft right now as I fill out the functionality with more tests (as well as testing manually myself), but this should accomplish what you're looking for.

Sorry this took so long!

@royassis

Hello @royassis, support for this was added in version 1.159.1. I believe your solution would look something like this:

    Metadata:
      Dockerfile: Dockerfile
      DockerContext: ./src
      DockerTag: latest
      DockerBuildExtraParams:
        - "--cache-to"
        - "user/app:cache ."
        - "--cache-from"
        - "user/app:cache ."

Basically, you just need to provide a list of params that you want to use in the metadata. I'm going to close this as completed, but if you have more questions or issues just reopen it and I'll take another look.

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Feature Request: Pass build params to docker/finch CLI #8656

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Feature Request: Pass build params to docker/finch CLI #8656

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reedham-aws commented on Feb 16, 2026

seshubaws commented on Mar 16, 2026

royassis commented on Mar 16, 2026

royassis commented on Mar 19, 2026

seshubaws commented on Mar 20, 2026

royassis commented on Mar 21, 2026

reedham-aws commented on Apr 11, 2026

reedham-aws commented on Apr 28, 2026

github-actions commented on Apr 28, 2026

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