Service Discovery

When running with data service it is possible to setup service auto-discovery.

Traefik is being used as a load-balancer and proxy for the main data service and provided that you follow a few simple steps, any number of micro-services can be associated with it.

Automatic Service Discovery

Traefik acts as a proxy and load balancer in a similar way to nginx. It listens on port 80 (or any other) and provides a gui (usually on 8080, but proxy.example.dev:80 gives access as well). LetsEncrypt can be setup to provide SSL as well as HTTP auth etc.

To register containers with Traefik (called proxy in the data project), you need to label the container with specific tags. Any web service should be labeled with:

• traefik.enable: true
• traefik.http.routers.service.rule: "Host(service.example.dev)"
• traefik.http.routers.service.tls: true
• traefik.http.services.service.loadbalancer.server.port: 8080

For example: to expose the example App API and have Traefik route it:

services:
  app:
    build:
      context: .
      dockerfile: src/Resources/docker/dev/app/Dockerfile
    networks:
      - app_example_network
    labels:
      traefik.enable: true
      traefik.http.routers.app.rule: "Host(`app.example.dev`)"
      traefik.http.routers.app.tls: true
      traefik.http.services.app.loadbalancer.server.port: 8080

The port is the INTERNAL container port, the frontend rule is how it should be accessed via Traefik. We could require the previous port by changing the rule to: Host(app.example.dev:4011)

All that is left to do is dc up -d and now Traefik will pick up the new container and it will be available immediately.

If you dc down services will automatically be removed.

As the Traefik config is done through labels, they can be added safely to docker-compose files without interfering with any other configuration.

Note: you need to ensure that the network is defined as an external type so that your containers will join the same resources. This network name is defined in the data-service project.

Note: The Traefik options must reference the container name. In the example above the container is named app and the labels reference this as routers.app.* and services.app.*. If you name your container something else e.g.: foobarbaz, then these would be routers.foobarbaz. and services.foobarbaz.*.