docker-compose traefik issue with PathRegexp

Question

What I am trying to do:

I have a docker-compose file with 4 containers traefik, UI, API and DB.

I want to use traefik to redirect both containers UI and API to port 80 but on a different url path. UI is redirected directly to localhost:80 and API I want to redirect to localhost/api, but the problem is that localhost/api is already taken in the UI container by valid html code. So I need to exclude it from the API routing or provide a valid PathRegexp which I am failing to create.

Here is the docker-compose where Iam trying PathRegexp:

Idea is to redirect only api endpointslike /api/endpoint1 or /api/endpoint2 but not redirect /api itself as that one I need to be redirected to UI container.

version: "3"

services:

  api:
    build:
      context: .
      dockerfile: ./api/dockerfile
    depends_on:
      - db
      - traefik
    labels:
      - "traefik.http.routers.api.rule=Host(`localhost`) && PathRegexp(`^/api/.*`)"
    ports:
      - 5000:5000

  ui:
    build:
      context: .
      dockerfile: ./ui/dockerfile
    depends_on:
      - api
      - db
      - traefik
    volumes:
      - ./ui/html/:/var/www/html
    labels:
      - "traefik.http.routers.ui.rule=Host(`localhost`)"
    ports:
      - 81:81
      - 443:443

  db:
    image: mysql
    restart: always
    env_file: .env
    environment:
        MYSQL_ROOT_PASSWORD: $ROOT_PASS_MYSQL
        MYSQL_DATABASE: $PRACTICE_DB
    ports:
      - 3307:3306
    volumes:
      - ./db/mysql:/docker-entrypoint-initdb.d/:ro

  traefik:
    image: traefik:v2.9
    command: --api.insecure=true --providers.docker
    ports:
      - 80:80
      - 8080:8080
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock

With this configuration I am getting an error:

error while parsing rule Host(localhost) && PathRegexp(^/api/.*): unsupported function: PathRegexp

Tschösi · Accepted Answer · 2024-01-10 10:05:00Z

0

PathRegexp does not exist (anymore). You can use Path or PathPrefix (see: https://doc.traefik.io/traefik/routing/routers/#rule)

You can use

traefik.http.routers.api.rule=Host(`localhost`) && PathPrefix(`/api/`)

This will send /api to the UI container (but /api/ goes to the other container).

If you need /api/(trailing slash) to go to the UI container, you can use a regex like so:

traefik.http.routers.api.rule=Host(`localhost`) && Path(`/api/{regex:.+}`)

Note that regex here is just the name of the match group, it can be changed to anything else. .+ makes sure that it only matches if there is at least one character after /api/.

In general, the longest rules have the highest priority.

edited Jan 10, 2024 at 10:05

answered Jan 9, 2024 at 14:56

Tschösi

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3 Comments

psova Over a year ago

thx, and how can i resolve my issue where i need the path /api/ to be redirected to UI container while everything after path /api/ (for example /api/test or /api/another-test) needs to be redirected to API container?

gh0st Over a year ago

If PathRegexp doesn’t exist anymore, why is it in the documentation? doc.traefik.io/traefik/routing/routers/…

gh0st Over a year ago

I’m a dummy. This person is using traefik v2.9. Disregard.

ddelange · Accepted Answer · 2025-03-04 11:38:24Z

0

The PathRegexp function is supported as of Traefik v3.1.0 (commit).

So if you got an unsupported function: PathRegexp error, chances are you are using Traefik v2.

answered Mar 4 at 11:38

ddelange

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