Service only supports one exposed port

[lukehoban]

Trying to create a single service with multiple ports exposed - such as:

let jaeger = new cloud.Service("jaeger", {
    containers: {
        nginx: {
            image: "jaegertracing/all-in-one:latest",
            memory: 1000,
            environment: { COLLECTOR_ZIPKIN_HTTP_PORT: "9411" },
            ports: [{ port: 16686 }, {port: 5778}, {port: 9411}],
        },
    },
});

Leads to:

error PU2012: aws:ecs/service:Service resource 'jaeger' has a problem: load_balancer: attribute supports 1 item maximum, config has 3 declared

This is due to http://docs.aws.amazon.com/AmazonECS/latest/developerguide/service-load-balancing.html:

There is a limit of one load balancer or target group per service.

That is a significant limitation that I was not previously aware of. It's not yet clear how we will work around this.

[lukehoban]

Aside: We could also identify and report a better error here assuming we don't have a forthcoming fix for this.

[lukehoban]

Kubernetes addresses this by separating the notion of Service and Deployment.

A Kubernetes Service handles the load-balancing and network addressability of a service.

A Kubernetes Deployment handles the managed deployment of a pod (collection of containers) at a specified number of replicas.

Unfortunately, ECS doesn't have such a split - the ECS Service is both of these, and there doesn't appear to be any way to decouple these.

[joeduffy]

I think ECS supports this for classic LBs with multiple listeners. I have to admit, I don't know specifically what that would lose us as this point, and whether that loss would be prohibitive.

[lukehoban]

#441 will help here by not requiring all visible ports to be publicaly exposed via a Load Balancer.

Beyond that, there's not much we're likely to do here until/unless AWS ECS makes changes. Closing out, and we'll reopen if we here more reports of issues here after addressing #441.