How to serve error page for unhealthy/crashed containers?

Traefik Traefik v2 (latest)
1

I'd like to show a custom error page instead of the "404 page not found" if one of my containers crashed or is unhealthy.

traefik:
    image: "traefik:v2.0"
   ...
catch-all:
    image: nginx:latest
    networks:
      - "main"
    logging:
      driver: json-file
    volumes:
    - ./error-pages/pages:/usr/share/nginx/error-pages
    - ./error-pages/default.conf:/etc/nginx/conf.d/default.conf
    - /etc/localtime:/etc/localtime:ro
    labels:
      traefik.enable: true
      traefik.http.routers.error-router.rule: HostRegexp(`{host:.+}`)
      traefik.http.routers.error-router.priority: 1
      traefik.http.routers.error-router.entrypoints: web
      traefik.http.routers.error-router.middlewares: error-pages-middleware

      traefik.http.routers.error-router-secure.rule: HostRegexp(`{host:.+}`)
      traefik.http.routers.error-router-secure.priority: 1
      traefik.http.routers.error-router-secure.entrypoints: web-secure
      traefik.http.routers.error-router-secure.middlewares: error-pages-middleware

      traefik.http.middlewares.error-pages-middleware.errors.status: 400-599
      traefik.http.middlewares.error-pages-middleware.errors.service: error-pages-service
      traefik.http.middlewares.error-pages-middleware.errors.query: "/404.html"

      traefik.http.services.error-pages-service.loadbalancer.server.port: 80

If I got a example container defined such as

services:
  test:
      container_name: test-web
      hostname: test-web
      image: nginx
      ports:
        - xxx:80
      volumes:
        - ./src:/usr/share/nginx/html
      networks:
      - "main"
      labels:
        - traefik.enable=true
        - traefik.http.routers.test.rule=Host(`test.example.com`)
        - traefik.http.routers.test.entrypoints=web
        - traefik.http.middlewares.redirect-to-https.redirectscheme.scheme=https
        - traefik.http.routers.test.middlewares=error-pages-middleware,redirect-to-https@docker
        - traefik.http.routers.test-secured.rule=Host(`test.example.com`)
        - traefik.http.routers.test-secured.tls=true
        - traefik.http.routers.test-secured.middlewares=error-pages-middleware
        - traefik.http.routers.test-secured.tls.certresolver=myhttpchallenge

it shows my custom error page thanks to the defined middleware when visiting ://example.com/does-not-exist.
When the test service is offline, I'd still get to see the error page when visiting the https://example.com page, but when using https://example.com I'm getting the plain old "404 page not found".

How to configure Traefik, so if a container was stopped I still get to see the custom error page for the web-secure entrypoint?

2

If the container is offline, the whole dynamic config is removed, so the middleware doesn’t work anymore.

You would probably need to define another catchall service with low priority (like 1) with a regex rule to match any request (or just the specific host), when higher priority router is not available.

3

Note: I never saw anyone using a Traefik v2.0 version from 2019. Why use a 5 year old version?