fix(riff-raff-generator): Correctly validate stacks

[akash1810]

Note

Recommended to review commit by commit as I've made some refactors along the way to improve readability.

What does this change?

This change validates more scenarios when instantiating a RiffRaffYamlFile to generate riff-raff.yaml. Given the below set of stacks, an Error will now be thrown as there is a missing instance of MyDatabaseStack for CODE.

new MyApplicationStack(app, "App-CODE-deploy", {
  env: {
    region: "eu-west-1",
  },
  stack: "deploy",
  stage: "CODE",
});
new MyApplicationStack(app, "App-PROD-deploy", {
  env: {
    region: "eu-west-1",
  },
  stack: "deploy",
  stage: "PROD",
});

new MyDatabaseStack(app, "Database-PROD-deploy", {
  env: {
    region: "eu-west-1",
  },
  stack: "deploy",
  stage: "PROD",
});

Previously, the validation would incorrectly pass, generating the below riff-raff.yaml.

Invalid `riff-raff.yaml`

allowedStages:
  - CODE
  - PROD
deployments:
  cfn-eu-west-1-deploy-my-application-stack:
    type: cloud-formation
    regions:
      - eu-west-1
    stacks:
      - deploy
    app: my-application-stack
    contentDirectory: /private/var/folders/0_/pvjwppsx5cl19t4n6_rmm_y80000gp/T/cdk.out9xIUJu
    parameters:
      templateStagePaths:
        CODE: App-CODE-deploy.template.json
        PROD: App-PROD-deploy.template.json
  cfn-eu-west-1-deploy-my-database-stack:
    type: cloud-formation
    regions:
      - eu-west-1
    stacks:
      - deploy
    app: my-database-stack
    contentDirectory: /private/var/folders/0_/pvjwppsx5cl19t4n6_rmm_y80000gp/T/cdk.out9xIUJu
    parameters:
      templateStagePaths:
        PROD: Database-PROD-deploy.template.json

How to test

See the added unit tests.

How can we measure success?

Correct validation when generating a riff-raff.yaml file.

Have we considered potential risks?

There are no changes to the public API, so I don't think there are any risks.

Checklist

• I have listed any breaking changes, along with a migration path ¹
• I have updated the documentation as required for the described changes ²

Footnotes

1. Consider whether this is something that will mean changes to projects that have already been migrated, or to the CDK CLI tool. If changes are required, consider adding a checklist here and/or linking to related PRs. ↩

2. If you are adding a new construct or pattern, has new documentation been added? If you are amending defaults or changing behaviour, are the existing docs still valid? ↩

[changeset-bot]

🦋 Changeset detected

Latest commit: 1824bae

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@guardian/cdk	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[akash1810]

Interestingly, this test (added in #2094) was incorrect!

[Copilot]

Pull request overview

Improves RiffRaffYamlFile validation so riff-raff.yaml generation fails when a stack “identity” (class name + stack tag + region) is missing required stage instances, preventing invalid templateStagePaths from being produced.

Changes:

• Refactors stack grouping to validate per (className, stackTag, region) and records missing stage definitions.
• Extracts grouping helpers and updates RiffRaffYamlFile to use them.
• Adds/updates unit tests and includes a changeset entry documenting the behavior change.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/riff-raff-yaml-file/index.ts	Refactors grouping/validation logic; adds missing-stack detection and region validation helper.
src/riff-raff-yaml-file/group-by.ts	Exposes grouping helpers and removes the previous combined grouping function.
src/riff-raff-yaml-file/types.ts	Removes the GroupedCdkStacks exported type alias.
src/riff-raff-yaml-file/index.test.ts	Updates snapshots and adds targeted validation tests for missing definitions/unresolved regions.
.changeset/silent-planets-invent.md	Documents the validation fix as a patch changeset.

Comments suppressed due to low confidence (1)

src/riff-raff-yaml-file/group-by.ts:20

• groupByClassNameStackRegionStage was removed. Since this file is importable via deep paths under @guardian/cdk/lib/..., removing an exported function can be a breaking change for downstream consumers. Consider keeping a compatibility export that delegates to the new groupByClassName/groupByStackTag/groupByRegion/groupByStageTag helpers (or add a deprecation period).

export function groupByClassName(cdkStacks: GuStack[]): Record<ClassName, GuStack[]> {
  return groupBy(cdkStacks, (stack) => stack.constructor.name);
}

export function groupByStackTag(cdkStacks: GuStack[]): Record<StackTag, GuStack[]> {
  return groupBy(cdkStacks, ({ stack }) => stack);
}

export function groupByStageTag(cdkStacks: GuStack[]): Record<StageTag, GuStack[]> {
  return groupBy(cdkStacks, ({ stage }) => stage);
}

export function groupByRegion(cdkStacks: GuStack[]): Record<Region, GuStack[]> {
  return groupBy(cdkStacks, ({ region }) => region);
}

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