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Traefik Cheat Sheet

Here are quick references for using Traefik on Docker containers environment.

I use Traefik in my docker compose project more frequently than using Nginx, as it has such advantages:

  • Simply to use and fast to spin up
    • Configuration relies on platform syntax(like Docker labels or Kubernetes annotations), while Nginx uses its own syntax and directives.
    • Configuration can just sit in docker-compose.yml, but Nginx always uses a dedicate configuration file(/etc/nginx/nginx.conf).
  • Dynamic configuration:
    • Changes to the configuration require a restart of the Nginx process
    • Changes to the configuration require a restart of its corresponding service, not the Traefik process

How a Request is processed in Traefik

Entrypoint -> Router -> Middleware 1 -> Middleware 2 -> ... -> Service

Redirect root path / to a subpath​

The goal is to redirect root path / to sub path /mtr that's an ingress for a web service:

  • http://127.0.0.1 -> http://127.0.0.1/mtr
  • http://127.0.0.1 -> http://127.0.0.1/mtr
  • https://127.0.0.1/something -> no redirect

It works for Traefik 2.0

services:
  traefik:
    image: traefik:v2.10
    command:
      - --api.insecure=true
      - --providers.docker=true
      - --providers.docker.exposedbydefault=false
      - --entrypoints.web.address=:80
    ports:
      - 80:80
      - 8080:8080 # Web UI Port
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    labels:
      - traefik.enable=true
      # Redirection from `http://xxx.com` to `http://xxx.com/foo`
      - traefik.http.routers.domain.entrypoints=web
      - traefik.http.routers.domain.rule=Path(`/`)
      - traefik.http.routers.domain.service=noop@internal
      - traefik.http.routers.domain.middlewares=to-foo@docker
      - traefik.http.middlewares.to-foo.redirectregex.permanent=true
      - traefik.http.middlewares.to-foo.redirectregex.regex=^http://([^/]+)/?$
      - traefik.http.middlewares.to-foo.redirectregex.replacement=http://$${1}/foo

  foo:
    image:  traefik/whoami:v1.10
    hostname: foo.com
    labels:
      - traefik.enable=true
      # just to ingress `http://xxx.com/foo`
      - traefik.http.routers.foo.entrypoints=web
      - traefik.http.routers.foo.rule=PathPrefix(`/foo`)

Route a prefix to a service​

Match a request with a prefix /bar, strip the prefix and route it to the bar service,

bar:
  image:  traefik/whoami:v1.10
  hostname: bar.com
  labels:
    - traefik.enable=true
    # ingress `http://xxx.com/bar/xyz` and send `http://xxx.com/xyz` to `bar` service
    - traefik.http.routers.bar.entrypoints=web
    - traefik.http.routers.bar.rule=PathPrefix(`/bar`)
    - traefik.http.routers.bar.middlewares=bar-strip-prefix@docker
    - traefik.http.middlewares.bar-strip-prefix.stripprefix.prefixes=/bar

Specify a custom port for the container​

By default, Traefik used the first exposed port of a container, if a container exposes multiple ports, set traefik.http.services.xxx.loadbalancer.server.port to override that port.

bar12345:
  image:  traefik/whoami:v1.10
  hostname: bar12345.com
  environment:
    WHOAMI_PORT_NUMBER: 12345
  labels:
    - traefik.enable=true
    - traefik.http.routers.bar12345.entrypoints=web
    - traefik.http.routers.bar12345.rule=PathPrefix(`/bar12345`)
    - traefik.http.routers.bar12345.service=bar12345
    # Tell Traefik to use the port 12345 to connect to `bar12345` service
    - traefik.http.services.bar12345.loadbalancer.server.port=12345

Specify more than one router and service per container​

In this example, requests are forwarded for http://127.0.0.1/web2ports-a to http://<private IP of container>:8001 in addition to http://127.0.0.1/web2ports-b forwarding to http://<private IP of container>:8002:

web2ports:
  image: python:3.10
  ports:
    - 8001:8001
    - 8002:8002
  working_dir: /app
  volumes:
    - ./server_whoami.py:/app/server_whoami.py
  command: >
    sh -c "python3 server_whoami.py --port 8001 
    & python3 server_whoami.py --port 8002"
  labels:
    - traefik.enable=true
    # Specify more than one router and service per container
    - traefik.http.routers.a-router.entrypoints=web
    - traefik.http.routers.a-router.rule=PathPrefix(`/web2ports-a`)
    - traefik.http.routers.a-router.service=a-service
    - traefik.http.services.a-service.loadbalancer.server.port=8001
    - traefik.http.routers.b-router.entrypoints=web
    - traefik.http.routers.b-router.rule=PathPrefix(`/web2ports-b`)
    - traefik.http.routers.b-router.service=b-service
    - traefik.http.services.b-service.loadbalancer.server.port=8002

Resources​

URL Redirect abc.com to xyz.com - Traefik v2 (latest) - Traefik Labs Community Forum

Traefik redirect / (root) to sub path with Docker labels · GitHub