(ecs): target a specific container and port for SRV service discovery

[misterjoshua]

I would like to point SRV service discovery records to specific ports on specific containers in tasks.

Use Case

When setting up a clustered Keycloak server, in addition to serving web traffic, the Keycloak instances need to talk among themselves using Infinispan/JGroups on a different port. The best way to accomplish this on ECS with bridge networking would be to use DNS-based service discovery, with the SRV record type. But this can only work if the SRV records can point to the Infinispan ports and not the same port as the web traffic. Currently, CDK's ECS Service constructs want to use the default (web) port on the default container, but in my case, I'd like SRV records pointing at Infinispan ports.

Proposed Solution

I would appreciate being able to tell service discovery which container and port to use for the SRV record. An interface like this would work:

new ecs.Ec2Service(stack, 'Service', {
  ...
  cloudMapOptions: {
    dnsRecordType: cloudmap.DnsRecordType.SRV,
    // New fields:
    container: specificContainerDefinition,
    containerPort: 81,
  },
});

Other

I have a PR linked to this issue.

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

---

This is a 🚀 Feature Request

[github-actions]

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