ActionCable websockets not working

[nerdinand]

I'm pretty sure I'm holding something wrong, but is there any special configuration to be done for Traefik to support ActionCable websockets?

My configuration works locally in development but I'm getting an NS_ERROR_WEBSOCKET_CONNECTION_REFUSED error in the Firefox network tab when a websocket is being opened.

The request indicates it's trying to connect to wss://mydomain.com/cable, but Traefik (or Rails?) is replying with a 301 Moved Permanently redirecting to: https://mydomain.com/cable.

This may be a mistake in how I configure ActionCable in general or a combination of ActionCable and Traefik. This is the first time I'm using ActionCable.

[hharen]

Is anyone else using ActionCable with Traefick or has an idea how to debug this?

[jmarchello]

I'm having the same issue, I think I have it narrowed down to the fact that my webapp can't reach redis (running on a seperate server, in the same VPC). From what I can tell, I can reach redis from my webapp's host, but not within the docker container. I'll let you know if/when I find out more.

[nerdinand]

I got it to work using the following configuration. Note that I'm also using traefik to terminate HTTPS (with let's encrypt), so your mileage may vary.

# deploy.yml

# ...

# Deploy to these servers.
servers:
  web:
    hosts:
      - 192.0.2.0
    labels:
      traefik.http.routers.kiqr_cloud_secure.entrypoints: websecure
      traefik.http.routers.kiqr_cloud_secure.rule: Host(`example.com`)
      traefik.http.routers.kiqr_cloud_secure.tls: true
      traefik.http.routers.kiqr_cloud_secure.tls.certresolver: letsencrypt

# Credentials for your image host.
registry:
  # Specify the registry server, if you're not using Docker Hub
  server: containers.example.com
  username: nerdinand
  password:
    - KAMAL_REGISTRY_PASSWORD

# Inject ENV variables into containers (secrets come from .env).
env:
  clear:
    POSTGRES_HOST: 192.0.2.0
    POSTGRES_USER: postgres
    REDIS_URL: redis://192.0.2.0:6379/1
  secret:
    - RAILS_MASTER_KEY
    - POSTGRES_PASSWORD

# Use accessory services (secrets come from .env).
accessories:
  postgres:
    image: postgres:16
    host: 192.0.2.0
    port: 5432
    env:
      clear:
        POSTGRES_USER: postgres
      secret:
        - POSTGRES_PASSWORD
    directories:
      - data/db:/var/lib/postgresql/data
  redis:
    image: redis:7
    host: 192.0.2.0
    port: 6379
    directories:
      - data/redis:/var/lib/redis/data

traefik:
  options:
    publish:
      - "443:443"
    volume:
      - "/letsencrypt/acme.json:/letsencrypt/acme.json"
  args:
    entryPoints.websecure.address: ":443"
    certificatesResolvers.letsencrypt.acme.email: "[email protected]"
    certificatesResolvers.letsencrypt.acme.storage: "/letsencrypt/acme.json"
    certificatesResolvers.letsencrypt.acme.httpchallenge: true
    certificatesResolvers.letsencrypt.acme.httpchallenge.entrypoint: web

I also removed config.force_ssl = true from production.rb and configured actioncable thusly:

config.action_cable.url = 'wss://example.com/cable'
config.action_cable.allowed_request_origins = ['https://example.com']

Hopefully that helps.