Docker Swarm with Traefik: containers are up but getting 404 - docker

Question

I am struggling to get a Docker swarm stack set up using traefik. I decided to try traefik as an alternative to jwolder/nginx-proxy, as unfortunately the latter does not seem to support Docker swrarm mode. But I'm finding traefik to be a problem (probably my fault!).
I have a WordPress container (replicated) and a MySQL container, alongside the traefik container. All of the containers in the swarm are created and start, and docker logs <container_id> reveals no errors, but when I visit 'example.org' (not the real domain) I just see 404 page not found. So it must be a communication issue between traefik and the containers I wish to proxy. However I also don't see the traefik dashboard, so perhaps soemthing else is going on.
Here is my docker-compose file:
version: '3'
services:
traefik:
image: traefik:latest
command: --api.insecure=true \
--providers.docker=true \
--providers.docker.exposedbydefault=false \
--providers.docker.swarmmode=true \
--providers.docker.watch=true \
--logLevel=DEBUG
ports:
- "80:80"
- "8080:8080"
volumes:
- /var/run/docker.sock:/var/run/docker.sock
networks:
- traefik
deploy:
mode: global
placement:
constraints:
- node.role == manager
db:
image: mysql:5.7
volumes:
- ./db/initdb.d:/docker-entrypoint-initdb.d
networks:
- traefik
environment:
MYSQL_ROOT_PASSWORD: <root_password>
MYSQL_DATABASE: <db_name>
MYSQL_USER: <db_user>
MYSQL_PASSWORD: <user_password>
deploy:
replicas: 1
restart_policy:
condition: on-failure
delay: 5s
max_attempts: 3
app:
image: my-repo/wordpress:latest
depends_on:
- db
networks:
- traefik
environment:
- VIRTUAL_PORT=80
- VIRTUAL_HOST=example.org
deploy:
replicas: 2
restart_policy:
condition: on-failure
delay: 5s
max_attempts: 3
labels:
- "traefik.enable=true"
- "traefik.frontend.rule=Host:example.org"
networks:
traefik:
The orignal nginx-proxy setup works nicely, but, as I say, won't allow me to run a swarm. I have been experimenting with traefik for only a day, so it's probably a schoolboy error of some kind.
N.B: I am aliasing my actual .org domain to 127.0.0.1 in my /etc/hosts. Perhaps that's an issue? I can't imagine it would be, I've been running Docker containers with that setup for ages without a problem.

Answer 1

OK, so I got it to work in non-swarm mode with the following docker-compose file:
version: '3'
services:
traefik:
image: "traefik:v2.0.0-rc3"
container_name: "traefik"
command:
- "--api.insecure=true"
- "--providers.docker=true"
- "--providers.docker.exposedbydefault=false"
- "--entrypoints.web.address=:80"
ports:
- "80:80"
- "8080:8080"
volumes:
- /var/run/docker.sock:/var/run/docker.sock
networks:
- traefik
db:
image: mysql:5.7
volumes:
- ./db/initdb.d:/docker-entrypoint-initdb.d
networks:
- traefik
environment:
MYSQL_ROOT_PASSWORD: <root_password>
MYSQL_DATABASE: <db_name>
MYSQL_USER: <db_user>
MYSQL_PASSWORD: <user_password>
app:
image: my-repo/wordpress:latest
depends_on:
- db
networks:
- traefik
labels:
- "traefik.enable=true"
- "traefik.http.routers.app.rule=Host(`example.org`)"
- "traefik.http.routers.app.entrypoints=web"
networks:
traefik:
And then I tried the following swarm configuration, which worked:
version: '3'
services:
traefik:
image: "traefik:v2.0.0-rc3"
command:
- "--api.insecure=true"
- "--providers.docker=true"
- "--providers.docker.swarmmode=true"
- "--providers.docker.exposedbydefault=false"
- "--providers.docker.endpoint=unix:///var/run/docker.sock"
- "--entrypoints.web.address=:80"
ports:
- "80:80"
- "8080:8080"
volumes:
- /var/run/docker.sock:/var/run/docker.sock
networks:
- traefik
deploy:
mode: global
placement:
constraints: [node.role==manager]
db:
image: mysql:5.7
volumes:
- ./db/initdb.d:/docker-entrypoint-initdb.d
networks:
- traefik
environment:
MYSQL_ROOT_PASSWORD: <root_password>
MYSQL_DATABASE: <db_name>
MYSQL_USER: <db_user>
MYSQL_PASSWORD: <user_password>
deploy:
replicas: 1
restart_policy:
condition: on-failure
delay: 5s
max_attempts: 3
app:
image: my-repo/wordpress:latest
networks:
- traefik
deploy:
replicas: 2
restart_policy:
condition: on-failure
delay: 5s
max_attempts: 3
labels:
- "traefik.enable=true"
- "traefik.http.routers.app.rule=Host(`example.org`)"
- "traefik.http.routers.app.entrypoints=web"
- "traefik.http.services.app.loadbalancer.server.port=80"
networks:
traefik:
More specifically, I got it to work only after adding the command
- "--providers.docker.endpoint=unix:///var/run/docker.sock"
and the proxied container label
- "traefik.http.services.app.loadbalancer.server.port=80"
... so I'm not really sure what I did right. Would be grateful for any light that could be shed on that.
It's working now, though, at least.
UPDATE: The Traefik docs state that the label
traefik.http.services.<service_name>.loadbalancer.server.port
is mandatory for Docker swarm mode (look under Services on that page). So it seems as if I was just missing that.