(aws-ecs): Give Cluster a method that provides task ARNs

[SamStephens]

Describe the feature

ARNs for tasks in a Cluster are in the form arn:{partition}:ecs:{region}:{accountId}:task/{clusterName}/{taskId}. It would be useful to have a method that can form these ARNs for you.

The aws-s3 Bucket class provides prior art for this with its arnForObjects method.

I guess this method would be called arnForTasks.

Use Case

In order to grant my task role permissions to the task protection API. My workaround is

        cluster_task_arn = Stack.of(self).format_arn(
            service='ecs',
            resource='task',
            resource_name=f'{fargate_cluster.cluster_name}/*'
        )
        fargate_task_definition.add_to_task_role_policy(
            aws_iam.PolicyStatement(
                actions=["ecs:UpdateTaskProtection"],
                resources=[cluster_task_arn],
            )
        )

With this method, the call would be

        fargate_task_definition.add_to_task_role_policy(
            aws_iam.PolicyStatement(
                actions=["ecs:UpdateTaskProtection"],
                resources=[fargate_cluster.arn_for_tasks('*')],
            )
        )

Proposed Solution

I'm not sure what best practice for forming ARNs within the CDK is, but using formatArn as I do in my example above would work.

Other Information

See also my request for a grantTaskProtection method

Acknowledgements

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

CDK version used

2.85.0

Environment details (OS name and version, etc.)

Ubuntu (Windows Subsystem for Linux)

[khushail]

Thanks for suggesting this feature @SamStephens , it would be a good and useful addition.

[github-actions]

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