(pipelines): add a way to add steps that aren't attached to stages

[markusl]

We receive an error "The given Stage construct ('foo/bar') should contain at least one Stack" when migrating our code to the modern pipelines.

Reproduction Steps

pipeline.addStage(new cdk.Stage(scope, 'MyStage'));

What did you expect to happen?

We would like to continue adding custom stages containing only CodeBuild projects and/or Lambda Invoke actions. Not all of our stages have stacks.

Environment

• CDK CLI Version : 1.117.0 (build 0047c98)
• Framework Version: 1.117.0 (build 0047c98)
• Node.js Version: v14.15.0
• OS : macOS
• Language (Version): TypeScript

Workaround

  const stage = new cdk.Stage(scope, 'MyStage');
  new cdk.Stack(stage, 'EmptyStackRemoveThis', {
    stackName: 'EmptyStackRemoveThis',
  });

---

This is 🐛 Bug Report

[rix0rrr]

addStage no longer means "add a CodePipeline Stage to the pipeline" -- it means: "deploy all stacks inside a cdk.Stage".

Adding arbitrary actions that have nothing to do with the deployment of CDK Stages is not strictly part of the design target, but I have a feeling using addWave, not adding any Stages to it and using post will do the same thing.

[markusl]

@rix0rrr thanks, addWave works indeed.

So basically, you cannot do this:

pipeline.addStage(createInfra('dev', ...));
pipeline.addStage(createInfra('test', ...));
pipeline.addStage(createInfra('prod', ...));

// Does not deploy stacks but only runs some post-production actions (CodeBuild/Lambdas)

const postproductionStage = new cdk.Stage(scope, 'PostProduction');
// ... add actions

pipeline.addStage(postproductionStage);

Instead users can do this:

pipeline.addStage(createInfra('dev', ...));
pipeline.addStage(createInfra('test', ...));
pipeline.addStage(createInfra('prod', ...));

// Does not deploy stacks but only runs some post-production actions (CodeBuild/Lambdas)
const postproductionWave = pipeline.addWave('PostProduction');
postproductionWave.addPost(...);

I have to admit that it was not very intuitive to use addWave to add a CodePipeline stage instead of using addStage for adding a stage :) In general, the new API seems quite intuitive and easy to use but maybe more of these use cases could be clarified in the docs?

Br,
Markus

[rix0rrr]

It's unfortunate that "Stage" and "Stage" are called the same thing. The new API does not deal in terms of Pipeline Stages, it just happens to create them as an implementation detail as part of you interacting with it.

[nnboskovic]

I'm having a similar issue with CDK for C#. I have a stage that instantiates a stack with several components and I'm getting the Amazon.JSII.Runtime.JsiiException: The given Stage construct ('api/deploy') should contain at least one Stack error.

https://gist.github.com/nnbosko/5570135b3e72731a5e7bdb61f75829a9

[nnboskovic]

Still occurring in version 119.