(aws-cdk): cdk bootstrap prints YAML template even when using --json option

[rantoniuk]

Describe the bug

OK, I'm either stupid and I'm missing something obvious or the command --show-template doesn't behave like it should.
The below commands are always printing the same template for me:

$ cdk bootstrap --show-template > x
$ cdk bootstrap --show-template --bootstrap-kms-key-id=AWS_KEY_MANAGED > x2
$ cdk bootstrap --show-template --bootstrap-customer-key > x3
$ cdk bootstrap --show-template --bootstrap-customer-key asd > x4
$ cdk bootstrap --show-template --json > x5

$ diff x* 
$
(no output, same files)

Why? There is no --dry-run- option, so I expect to be able to see the template modified with the CLI options to validate before actual deployment. Instead, even -j does not have any effect whatsoever for me. Am I missing something?

Also, in the template I see that it's possible to use AWS_MANAGED_KEY for FileAssetsBucketKmsKeyId.
Shouldn't this be possible to enable this via CLI (and be documented in cdk bootstrap -h) ?

I even tried to do the following:

1. cdk bootstrap --show-template > template
2. (edited the template file and set FileAssetsBucketKmsKeyId to AWS_MANAGED_KEY
3. cdk bootstrap --cloudformation-execution-policies arn:aws:iam::aws:policy/AdministratorAccess aws://XXX/eu-west-1 --template template --no-execute

Result:

• CDKToolkit: creating CloudFormation changeset... Environment bootstrapped (no changes).
• CloudFormation shows an empty and FAILED changeset.

CDK CLI Version

2.35.0 (build 5c23578)

Framework Version

No response

Node.js Version

v14.19.3

OS

MacOS

Language

Typescript

Language Version

No response

Other information

No response

[rantoniuk]

I was able to effectively re-bootstrap (update) the bucket by using cdk bootstrap --bootstrap-kms-key-id arn:aws:kms:eu-west-1:..... command, but without review.
The changeset that was created with --no-execute was either empty or it contained "modify" on some resources but I was unable to see how the resources are going to be modified (which is the purpose of the ChangeSet review right?)

[peterwoodworth]

These options aren't going to show changes because they make use of CloudFormation parameters. Supplying a different parameter will not show a difference in the template.

The --json option isn't working here because that option is a global option showing for all our commands, but it isn't actually enabled for the bootstrap command. Could be changed here where it gets printed

aws-cdk/packages/aws-cdk/lib/api/bootstrap/bootstrap-environment.ts

Line 38 in cf3bb6e

process.stdout.write(`${toYAML(template)}\n`);

[arewa]

Hi @peterwoodworth and @rantoniuk , I prepared a fix and it was already merged, perhaps we could resolve this issue.

[github-actions]

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