Load Balancer Service Port Discovery

Archive Rancher 1.x
1

What’s the best way to do Port Discovery between 2 Rancher Stacks?

In my test case I have a single container of redis with a tcp load balancer in one stack and a second stack with a simple application container that has the redis-cli installed for testing.

If I link directly to the redis instance (master) I get the standard set of docker --link variables.

If I link to the rancher lb service I don’t get those variables.

So how do I programmatically figure out what port the linked to service is listening on?

I was leaning to using the --link variables, since docker linking is native and not rancher specific, but I did notice there might be other ways, DNS service, and the http metadata service.

I was looking at the json file for the DNS service, but it didn’t seem to provide any extra records with metadata or port information.

I do know there is a metadata (ec2 style) service, but I’m not sure how stable it is at this point.

Any guidance on the “Rancher” way would be helpful.

###Redis Stack
docker-compose.yml

redis-internal:
  expose:
  - 6379:6379/tcp
  tty: true
  image: rancher/load-balancer-service
  links:
  - master:master
  stdin_open: true

master:
  labels:
    io.rancher.container.pull_image: always
  command:
  - redis-server
  - --save
  - ''
  - --maxmemory
  - 1gb
  tty: true
  image: redis:3.0.7
  stdin_open: true

rancher-composer.yml

redis-internal:
  scale: 1
  load_balancer_config:
    haproxy_config: {}
  health_check:
    port: 42
    interval: 2000
    unhealthy_threshold: 3
    healthy_threshold: 2
    response_timeout: 2000
master:
  scale: 1
  health_check:
    port: 6379
    interval: 1000
    unhealthy_threshold: 1
    response_timeout: 500
    healthy_threshold: 1

####My App Service
docker-compose.yml

app:
  external_links:
  - redis/redis-internal:redis
  labels:
    io.rancher.container.pull_image: always
  tty: true
  image: redis:3.0.7
  stdin_open: true

rancher-compose.yml

app:
  scale: 1
2

You can use the Rancher metadata service to get any information on any service in Rancher.

http://docs.rancher.com/rancher/metadata-service/