(sns): default .fifo suffix for FIFO topics

[skyrpex]

Description

#12386 introduced a requirement to add a topic name whenever a FIFO topic is created.

Do you think it's a good idea to generate a default name if it isn't provided by the user? All of the other CDK resources are named consistently using something similar to what cdk.Names.nodeUniqueId(node) does, ie MyStack2EC66409Topic.fifo, which prevents name collisions.

Use Case

Remove the need to manually define a topic name.

Proposed Solution

This is my current implementation:

import * as cdk from "aws-cdk-lib"
import { Construct, Node } from "constructs"

export class Topic extends cdk.aws_sns.Topic {
  public constructor(
    scope: Construct,
    id: string,
    properties?: cdk.aws_sns.TopicProps,
  ) {
    super(scope, id, {
      ...properties,
      topicName:
        properties?.topicName ?? properties?.fifo
          ? buildFifoName(scope.node, id)
          : undefined,
    })
  }
}

export function buildFifoName(node: Node, id: string) {
  const uniqueId = cdk.Names.nodeUniqueId(node)
  const suffix = `${id}.fifo`
  // Make sure that the name fits within the CFN's 80 character limit
  return `${uniqueId.slice(0, Math.max(0, 80 - suffix.length))}${suffix}`
}

Other information

No response

Acknowledge

• I may be able to implement this feature request
• This feature might incur a breaking change

[njlynch]

It looks like CloudFormation has it on their roadmap to fix this so a topic name doesn't need to be input at creation; however, there's not been on update on the issue in over a year:
aws-cloudformation/cloudformation-coverage-roadmap#681

The above proposal -- to autogenerate a name and suffix the '.fifo' if a name is not provided -- sounds reasonable to me. Contributions welcome!

[mjsztainbok]

There is an issue with the code above. If you look at SQS (for example), the names for queues are generated using the stack name as the prefix. In this case though it looks like Names.uniqueId() just uses the ID of the stack for the prefix of the unique ID which causes issues if you have multiple instances of the same stack but with different stack names (which is what we are doing so that we can have individual stacks for development and CI/CD test purposes).

I modified the code as follows to correct this:

 private static replaceStackId(scope: Construct, id: string): string {
    const stack = cdk.Stack.of(scope);

    // Replace the stack ID in the identifier with the stack name
    return id.replace(stack.node.id, stack.stackName);
  }

  private static buildFifoName(scope: Construct, id: string) {
    const uniqueId = this.replaceStackId(
      scope,
      cdk.Names.uniqueId(scope)
    );
    const suffix = `${id}.fifo`;
    // Make sure that the name fits within the CFN's 80 character limit
    return `${uniqueId.slice(0, Math.max(0, 80 - suffix.length))}${suffix}`;
  }

[dreamorosi]

I think this issue could be closed. The PR with the fix has been merged and the new behavior has been released yesterday

[github-actions]

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