Adding Traefik StripPrefix middleware to docker-compose labels results in 504 - docker

Question

I have developed several docker-ized full-stack web applications that I am trying to route requests to using Traefik. I want to take advantage of the dynamic configuration via docker-compose labels. I would like to apply the stripPrefix middleware option so I can use the same application routing as if each app were served at the root. However, once these rules are applied it results in a 504 Gateway Timeout response.
Here's my set up:
Traefik 2.0.1
Docker 19.03.2, Compose 1.24.1
NGINX:latest images
A global docker network on which the Traefik container runs
Multiple multi-container applications, each of which includes an NGINX web server
All applications have their own local networks and the NGINX containers are also on the global network.
Each application is configured to be listening at /
Here is the docker-compose.yml definition for the offending NGINX container:
nginx:
image: nginx:latest
container_name: "mps_nginx"
volumes:
- ./nginx/confs/nginx.conf:/etc/nginx/default.conf
- ./static:/www/static
restart: "always"
labels:
- traefik.http.routers.mps.rule=Host(`localhost`) && PathPrefix(`/mps`)
- traefik.http.middlewares.strip-mps.stripprefix.prefixes=/mps
- traefik.http.routers.mps.middlewares=strip-mps#docker
networks:
- default
- mps
The aggravating part is, when I comment out the middlewares labels, it runs just fine but cannot find a matching URL pattern.
Prior to this I tested my approach using the whoami container that is defined in the Traefik Quickstart Tutorial:
# Test service to make sure our local docker-compose network functions
whoami:
image: containous/whoami
labels:
- traefik.http.routers.whoami.rule=Host(`localhost`) && PathPrefix(`/whoami`)
- traefik.http.middlewares.strip-who.stripprefix.prefixes=/whoami
- traefik.http.routers.whoami.middlewares=strip-who#docker
A request to http://localhost/whoami returns (among other things)
GET / HTTP/1.1.
This is exactly how I expected my routing approaches to work for all my other applications. The Traefik dashboard shows green all around for every middleware I register and yet all I see is 504 errors.
If anyone has any clues I would sincerely appreciate it.

Answer 1

To summarize my solution to a similar problem
my-service:
image: some/image
ports: # no need to expose port, just to show that service listens on 8090
- target: 8090
published: 8091
mode: host
labels:
- "traefik.enable=true"
- "traefik.http.routers.myservice-router.rule=PathPrefix(`/myservice/`)"
- "traefik.http.routers.myservice-router.service=my-service"
- "traefik.http.services.myservice-service.loadbalancer.server.port=8090"
- "traefik.http.middlewares.myservice-strip.stripprefix.prefixes=/myservice"
- "traefik.http.middlewares.myservice-strip.stripprefix.forceslash=false"
- "traefik.http.routers.myservice-router.middlewares=myservice-strip"
Now details
Routing rule
... redirect all calls thats path starts with /myservice/
- "traefik.http.routers.myservice-router.rule=PathPrefix(`/myservice/`)"
... to service my-service
- "traefik.http.routers.myservice-router.service=my-service"``
... to port 8090
- "traefik.http.services.myservice-service.loadbalancer.server.port=8090"
... and uses myservice-strip middleware
- "traefik.http.routers.myservice-router.middlewares=myservice-strip"
... this middleware will strip /myservice from path
- "traefik.http.middlewares.myservice-strip.stripprefix.prefixes=/myservice"
... and will not add trailing slash (/) if path becomes an empty string
- "traefik.http.middlewares.myservice-strip.stripprefix.forceslash=false"

Answer 2

There is an issue with prefix without ending with '/'.
Test your config like this:
- "traefik.http.routers.whoami.rule=Host(`localhost`) && (PathPrefix(`//whoami/`) || PathPrefix(`/portainer`))"
- "traefik.http.middlewares.strip-who.stripprefix.prefixes=/whoami"

Answer 3

I had a similar problem that was solved with the addition of
- "traefik.http.middlewares.strip-who.stripprefix.forceslash=true"
It makes sure the strip prefix doesn't also remove the forward slash.
You can read more about the forceslash documentation https://docs.traefik.io/middlewares/stripprefix/