Codebuild: Removing Cache property does not revert cache to NO_CACHE

[NeilBostrom]

What is the problem?

First setting Cache = Cache.Local(LocalCacheMode.DOCKER_LAYER), on a CodeBuild Project and deploying will correctly set the Cache setting on the project.
If you remove the Cache set from your source code, the CodeBuild project is not reverted back to NO_CACHE. It leaves the previous DOCKER_LAYER in place.
This is unexpected as most properties revert to their default option when removed.

Reproduction Steps

            var project = new Project(this, $"{ServiceName}CodeBuild", new ProjectProps
            {
                ProjectName = "Test",
                Cache = Cache.Local(LocalCacheMode.DOCKER_LAYER),
                BuildSpec = BuildSpec.FromObject(new Dictionary<string, object>
                {
                    ["version"] = "0.2",
                    ["phases"] = new Dictionary<string, object>
                    {
                        ["build"] = new Dictionary<string, object>
                        {
                            ["commands"] = new string[] {
                                "rake build[${CODEBUILD_BUILD_NUMBER}]"
                            }
                        }
                    }
                }))
            });

What did you expect to happen?

Removing the Cache = should revert the CodeBuild project to NO_CACHE

What actually happened?

Nothing, removing the property leaves the previous caching property in place.

CDK CLI Version

2.3.0 (build beaa5b2)

Framework Version

No response

Node.js Version

v14.16.1

OS

Windows 11

Language

.NET

Language Version

.NET Core 6

Other information

The reason I spotted this was that I'm in the process of moving to arm64 in our CodeBuild projects. Applying the following change to our CDK stack fails:

Failed to call UpdateProject, reason: Invalid cache type: local caching is not supported for projects with environment type ARM_CONTAINER and compute type BUILD_GENERAL1_SMALL (Service: AWSCodeBuild; Status Code: 400; Error Code: InvalidInputException; Request ID: 19e3b77c-fcf9-4440-a8ac-1610fb441656; Proxy: null)
        new Project (/tmp/jsii-kernel-moicem/node_modules/@aws-cdk/aws-codebuild/lib/project.js:355:26)
        \_ /tmp/0lk2tlal.3bx/lib/program.js:8432:58
        \_ Kernel._wrapSandboxCode (/tmp/0lk2tlal.3bx/lib/program.js:8860:24)
        \_ Kernel._create (/tmp/0lk2tlal.3bx/lib/program.js:8432:34)
        \_ Kernel.create (/tmp/0lk2tlal.3bx/lib/program.js:8173:29)
        \_ KernelHost.processRequest (/tmp/0lk2tlal.3bx/lib/program.js:9757:36)
        \_ KernelHost.run (/tmp/0lk2tlal.3bx/lib/program.js:9720:22)
        \_ Immediate._onImmediate (/tmp/0lk2tlal.3bx/lib/program.js:9721:46)
        \_ processImmediate (internal/timers.js:464:21)

[skinny85]

Thanks for opening the issue @NeilBostrom. The problem you're running into, I'm pretty sure, is that the CodeBuild API treats not provided fields as unchanged, and that's why removing the Cache property doesn't have any effect.

The correct way to unblock yourself would be to use Cache.None() instead of Cache.Local(), however I discovered a bug in how that method is implemented. I submitted a fix in #18194 - once that is merged and released in a new CDK version, providing Cache.None() should do the trick.

Apologies for the bad experience.

Thanks,
Adam

[skinny85]

In the meantime, you can try using escape hatches to set the cache type to NO_CACHE.

[NeilBostrom]

Thanks @skinny85. I thought that might be the case, it was just a little unexpected. Feel free to close this and hopefully it will help someone along their similar journey of Googling.

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