How to define routers priority or define a service when no one router meets the request?

Traefik Traefik v2 (latest)
,
1

TLDR:

  • How to set priority between different services?
  • How do I set middleware errors to respond to 404 errors that do not respond to any defined routes?

Hello,

In my project, I use traefik to define access to different containers through the subdomain. I worked out a strategy to stop docker containers on weekends and restart they when were requested during the week.

In v1, I had developed with a strategy similar to that:

There are one container with minimum priority that responds all subdomains requests that are not used and eventually restarts a stopped container if is one associated with the subdomain

labels:
  - traefik.nao-disponivel.frontend.rule=HostRegexp(`{subdomain:.+}.${DOMINIO}`)
  - traefik.nao-disponivel.frontend.priority=1

In v2, I try to create a router to responds all subdomains

labels:
  # Middleware Redirect https
  - traefik.http.middlewares.redirect_https.redirectregex.regex=^http://(.*)
  - traefik.http.middlewares.redirect_https.redirectregex.replacement=https://$${1}

  # Http to https
  - traefik.http.routers.ambientes_nao_disponivel_http.rule=HostRegexp(`{subdomain:.+}.localhost`)
  - traefik.http.routers.ambientes_nao_disponivel_http.middlewares=redirect_https

  # Https
  - traefik.http.routers.ambientes_nao_disponivel_https.rule=HostRegexp(`{subdomain:.+}.localhost`)
  - traefik.http.routers.ambientes_nao_disponivel_https.tls=true

I tested and verified that the rule has higher priority than any container that defined a subdomain.

Question 1: I didn't find in the documentation how to set a priority on the router.

Question 2: A workaround would be to set a default service for requests that do not fit into any router defined for traefik. Is there this option?

I tried to define an error middleware in the root domain (localhost), but got no results.

Configuration 
version: '3.7'

services:
  traefik:
    image: traefik:v2.0.0-rc3-alpine
    command: >
      --api=true
      --api.dashboard=true
      --api.insecure=true
      --providers.docker=true
      --entryPoints.web.address=:80
      --entryPoints.web-secure.address=:443
      --log.level="DEBUG"
    restart: always

    ports:
      - "80:80"     # The HTTP port
      - "443:443"   # The HTTPS port
    labels:
      # Traefik dashboard in subdomain: traefik.localhost 
      - traefik.http.routers.traefik_http.rule=Host(`traefik.localhost`)
      - traefik.http.routers.traefik_http.middlewares=redirect_https
      - traefik.http.routers.traefik_http.entryPoints=web

      - traefik.http.routers.traefik_https.rule=Host(`traefik.localhost`)
      - traefik.http.routers.traefik_https.tls=true
      - traefik.http.routers.traefik_https.entryPoints=web-secure

      - traefik.http.services.traefik_https.loadbalancer.server.port=8080

      # Middlewares
      ## 404 -> Custom service
      - traefik.http.middlewares.404_not_found.errors.status=404
      - traefik.http.middlewares.404_not_found.errors.service=404_not_found_https
      - traefik.http.middlewares.404_not_found.errors.query=/
      ## Redirect https
      - traefik.http.middlewares.redirect_https.redirectregex.regex=^http://(.*)
      - traefik.http.middlewares.redirect_https.redirectregex.replacement=https://$${1}

    volumes:
      - /var/run/docker.sock:/var/run/docker.sock 
    networks:
      - ambientes


  ambientes-cliente:
    build:
      context: .
      dockerfile: ambientes-cliente.Dockerfile
    command: npm run ${AMBIENTE_EXECUCAO}
    restart: always

    depends_on:
      - traefik

    labels:
      - traefik.http.routers.ambientes_cliente_http.rule=Host(`localhost`)
      - traefik.http.routers.ambientes_cliente_http.middlewares=redirect_https
      - traefik.http.routers.ambientes_cliente_http.entryPoints=web

      - traefik.http.routers.ambientes_cliente_https.rule=Host(`localhost`)
      - traefik.http.routers.ambientes_cliente_https.tls=true
      - traefik.http.routers.ambientes_cliente_https.middlewares=404_not_found
      - traefik.http.routers.ambientes_cliente_https.entryPoints=web-secure

      - traefik.http.services.ambientes_cliente_https.loadbalancer.server.port=8100
    networks:
      - ambientes
    volumes:
      - ...

  ambiente-nao-disponivel:
    depends_on:
      - traefik
    image: python:3-alpine
    command: sh setup.sh
    restart: always

    labels:
      - traefik.http.routers.404_not_found_http.rule=HostRegexp(`404.localhost`)
      - traefik.http.routers.404_not_found_http.middlewares=redirect_https

      - traefik.http.routers.404_not_found_https.rule=HostRegexp(`404.localhost`)
      - traefik.http.routers.404_not_found_https.tls=true

      - traefik.http.services.404_not_found_https.loadbalancer.server.port=5000

    networks:
      - ambientes
    volumes:
      - ...

networks:
  ambientes:
    name: ambientes
    driver: bridge
2

Hello, the solution is the priority router param:

- traefik.http.routers.ambientes_nao_disponivel_http.priority=1

This has already implemented, but no documented:

https://docs.traefik.io/v2.0/reference/dynamic-configuration/docker/