Simplify backend generation to avoid port publishing

[vincentlepot]

In order to avoid port publishing when using Swarm services, the backend generation is based upon service name and service port (given by the interlock.port label on service).

The example has been updated accordingly.

[ehazlett]

How do we handle backward compatibility and non-Swarm mode here?

[vincentlepot]

As far as I understood, I didn't touch the pure container part, hence the backward compatibility should not be impacted. But maybe you have a use case in mind where it does not work?

[vincentlepot]

Ah! One more thing, I only treated the swarm services case, for container, I haven't looked at a solution to avoid publishing port.

[sedouard]

So I'm testing this PR out with a compose stack deployment (docker stack). It seems like it interlock can't find the exposed ports, even though docker container inspect for the container returns:

"Ports": {
                "3000/tcp": null
}

I'm deploying with interlock in a compose file with:

interlock:
    image: sedouard/interlock:swarm-mode # <- just a build of this pull-request source branch
    command: -D run -c /etc/interlock/config.toml
    tty: true
    deploy:
      mode: replicated
      replicas: 2
      placement:
        constraints:
          - node.labels.type == web-server
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:rw
    networks:
      - redis-network
    depends_on:
      - nginx
    ports:
        - 8080:8080
    environment:
        INTERLOCK_CONFIG: |
            ListenAddr = ":8080"
            DockerURL = "unix:///var/run/docker.sock"
            PollInterval = "2s"
            [[Extensions]]
            Name = "nginx"
            ConfigPath = "/etc/nginx/nginx.conf"
            PidPath = "/var/run/nginx.pid"
            TemplatePath = ""
            MaxConn = 1024
            Port = 80
nginx:
    image: nginx:1.11
    entrypoint: nginx
    command: -g "daemon off;" -c /etc/nginx/nginx.conf
    ports:
        - 80:80
    labels:
        - "interlock.ext.name=nginx"
    deploy:
      mode: global
      placement:
        constraints:
          - node.labels.type == web-server
    networks:
      - redis-network
api:
    image: sedouard/api:latest
    ports:
      - 3000
    networks:
      - redis-network
deploy:
      mode: global
      placement:
        constraints:
          - node.labels.type == web-server

The line of code is:
https://github.com/vincentlepot/interlock/blob/20c3e0e1f6739eb388f5476940a2aef630b12467/ext/lb/nginx/generate.go#L89

where it seems to just be looking to see if there are >0 ports in the Ports bag

[sedouard]

Silly me -- my labels weren't under the deploy key.

[ehazlett]

cool :). I'm not sure we can merge this until the non swarm mode issue is addressed.

[vincentlepot]

What's the problem with non swarm mode case?

[vincentlepot]

Sorry I haven't looked here for a while since I used another solution for my use case. But if you need me to finish this PR, just tell me what you think is missing