feat: Add Stack Set support

[akash1810]

What does this change?

Create constructs to support the creation of AWS::CloudFormation::StackSet resources. Unfortunately, AWS CDK does not (yet) have a L2 construct for Stack Sets 😢 .

Usage:

// the infrastructure to create in target accounts
class AccountAlertTopic extends GuStackForStackSetInstance {
  constructor(id: string, props: GuStackProps) {
    super(id, props);

    new GuSnsTopic(this, "topic-for-alerts");
  }
}

// the infrastructure to create in the root account
class ParentStack extends GuStackForInfrastructure {
  constructor(scope: App, id: string, props: GuStackProps) {
    super(scope, id, props);

    new GuStackSet(this, `${id}StackSet`, {
      stackSetInstance: new AccountAlertTopic("Alerts", { stack: props.stack }),
      name: "centralised-alarms",
      description: "Provisioning of standard account alerting resources",
      organisationUnitTargets: [ "o-abcde12345" ]
    });
  }
}

// contents of `bin/cdk.ts`
new ParentStack(new App(), "AccountAlarmResources", { stack: "alarms" })

This will produce a CloudFormation template like this:

Resources:
  AccountAlarmResourcesStackSet:
    Type: AWS::CloudFormation::StackSet
    Properties:
      PermissionModel: SERVICE_MANAGED
      StackSetName: centralised-alarms
      AutoDeployment:
        Enabled: true
        RetainStacksOnAccountRemoval: false
      Description: Provisioning of standard account alerting resources
      Parameters: []
      StackInstancesGroup:
        - DeploymentTargets:
            OrganizationalUnitIds:
              - o-abcde12345
          Regions:
            - Ref: AWS::Region
      Tags:
        - Key: gu:cdk:version
          Value: TEST
        - Key: gu:repo
          Value: guardian/cdk
        - Key: Stack
          Value: alarms
        - Key: Stage
          Value: INFRA
      TemplateBody: |-
        {
          "Resources": {
            "topicforalerts57330FBE": {
              "Type": "AWS::SNS::Topic",
              "Properties": {
                "Tags": [
                  {
                    "Key": "gu:cdk:version",
                    "Value": "TEST"
                  },
                  {
                    "Key": "gu:repo",
                    "Value": "guardian/cdk"
                  },
                  {
                    "Key": "Stack",
                    "Value": "alarms"
                  },
                  {
                    "Key": "Stage",
                    "Value": "INFRA"
                  }
                ]
              }
            }
          }
        }

See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cloudformation-stackset.html.

Note: this does not support provisioning of stack sets to specific accounts as I'm not sure why we'd ever do this.

How to test

See added tests.

How can we measure success?

We get a step closer to a better stack set deployment story as, by provisioning stack sets as just another resource in a CloudFormation template, we're closer to being able to deploy them via RIff-Raff like any other infrastructure.

Have we considered potential risks?

Do the construct names make sense and are they intention revealing enough?

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? ↩

[jacobwinch]

I find this naming very clear 👍

[jacobwinch]

Great work 💯

[github-actions]

🎉 This PR is included in version 31.5.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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