[cli] Caller should be able to override created changeset name

[muja]

When invoking cdk deploy with the --no-execute flag, CDK will create a changeset whose name is completely random. Usually this might be okay, but in automated environments this is unacceptable. As such, it should be possible to provide a name which CDK will use when creating a changeset (e.g. using a --change-set-name <string> flag).

Use Case

Our CI/CD environment runs on top of CodePipeline in combination with CodeBuild (and very extensive use of CDK). Naturally, our initial approach was to simply do a cdk deploy inside our CodeBuild containers. However, the stack creation/update itself often takes several minutes with the computing instance just waiting for the stack create to finish. This is not very cost-efficient.
So, to save resources and costs, the CodeBuild containers should not execute the changeset, only create it so that CodePipeline's CloudFormationExecuteChangeSetAction can take over. However, this specific deploy action needs the changeset name which must be known at create time (the Fn::GetParam function unfortunately only works for TemplateOverrides, tried that already).

Proposed Solution

I believe the solution is simple: the CLI should accept a --change-set-name <string> option, and pass this optional parameter to the deployStack function. This one should use the parameter, if provided, or fallback to the existing uuid.v4() method. This can also be used in combination with --execute, but there it will be significantly less interesting.

Other

For our use case... we tried going with cdk synth and CreateStackAction shenanigans, but this leads to many more problems:

• we have lots of assets which will not get uploaded in cdk synth, so we'd have to do it all manually or introduce the cdk-assets package.
• CodePipeline uses some other role for the stack than CDK (which is hard to override without diving into CDK internals) and since we have KMS encrypted S3 buckets, this approach led to many hard-to-debug S3 API errors.
• you cannot provide NotificationArns with this approach which are also used by us

• 👋 I may be able to implement this feature request

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This is a 🚀 Feature Request

[rix0rrr]

We could add this. Out of curiosity: have you considered using CDK Pipelines?

[markussiebert]

I would like to see this feature. I want to continue using gitlabci and don't want to switch :-)

[swar8080]

The CDK automatically deletes empty change sets, so I'm wondering if an additional flag is needed to retain empty change sets. Otherwise, use cases for externally executing the change set would need to check for its existence before executing to avoid errors.

For @muja's case with the CodePipeline Cloudformation action, the action fails if the change set with the provided name doesn't exist. I'm not very familiar with Codepipeline, but didn't see a straight-forward way to conditionally skip that Cloudformation action. The action is successful when the change set is empty, so retaining it would solve the problem.