Dozzle has connection issues behind Traefik

[SolitudePy]

🔍 Check for existing issues

• Completed

How is Dozzle deployed?

Standalone Deployment

📦 Dozzle version

v8.14.12

✅ Command used to run Dozzle

services:
  dozzle-socket-proxy:
    image: linuxserver/socket-proxy
    container_name: dozzle-socket-proxy
    restart: unless-stopped
    environment:
      - CONTAINERS=1       # allow GET /containers/json and /containers/{id}/json
      - POST=0             # disallow any container modifications
      - INFO=1
      - EVENTS=1 
      - LOG_LEVEL=debug
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    networks:
      - dozzle_socket_net
  dozzle:
    image: amir20/dozzle:latest
    container_name: dozzle
    #volumes:
    #  - /var/run/docker.sock:/var/run/docker.sock
    depends_on:
      - dozzle-socket-proxy
    environment:
      DOZZLE_ENABLE_SHELL: false
      DOZZLE_ENABLE_ACTIONS: false
      DOZZLE_NO_ANALYTICS: false
      DOCKER_HOST: tcp://dozzle-socket-proxy:2375
      DOZZLE_REMOTE_AGENT: <IP>:7007
    restart: unless-stopped
    networks:
      - proxy_net
      - dozzle_socket_net
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.dozzle.rule=Host(`dozzle.lan`)"
      - "traefik.http.routers.dozzle.entrypoints=websecure"
      - "traefik.http.routers.dozzle.tls.certresolver=desec"
      - "traefik.http.services.dozzle.loadbalancer.server.port=8080"

      # Tried with and without these
      - "traefik.http.routers.dozzle.middlewares=dozzle-compress,dozzle-buffering"
      - "traefik.http.middlewares.dozzle-compress.compress.excludedContentTypes=text/event-stream"
      - "traefik.http.middlewares.dozzle-buffering.headers.customrequestheaders.X-Accel-Buffering=no"

networks:
  proxy_net:
    external: true
  dozzle_socket_net:

🐛 Describe the bug / provide steps to reproduce it

I am getting a known error that dozzle UI cant connect to the API. its traefik related, didnt have this with nginx-proxy-manager, my traefik version is v3.6.6 (latest), tried multiple middlewares, still happens from time to time.

💻 Environment

Client: Docker Engine - Community
 Version:    28.3.2
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.25.0
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.38.2
    Path:     /usr/libexec/docker/cli-plugins/docker-compose
  model: Docker Model Runner (EXPERIMENTAL) (Docker Inc.)
    Version:  v0.1.33
    Path:     /usr/libexec/docker/cli-plugins/docker-model

Server:
 Containers: 30
  Running: 30
  Paused: 0
  Stopped: 0
 Images: 28
 Server Version: 28.3.2
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 CDI spec directories:
  /etc/cdi
  /var/run/cdi
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 05044ec0a9a75232cad458027ca83437aae3f4da
 runc version: v1.2.5-0-g59923ef
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.12.34+rpt-rpi-2712
 Operating System: Debian GNU/Linux 12 (bookworm)
 OSType: linux
 Architecture: aarch64
 CPUs: 4
 Total Memory: 15.84GiB
 Name: pi
 ID: 9a8f2b94-ba4b-4784-ba2b-1ad1e94fb548
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Experimental: true
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Live Restore Enabled: false

📜 Dozzle logs are required for debugging purposes. You may need to enable debug mode. See https://dozzle.dev/guide/debugging.

debug logs are all normal not informative to the UI error.

📸 If applicable, add screenshots to help explain your bug

[amir20]

tried multiple middlewares, still happens from time to time.

Did you mean to report this as bug. Doesn't seem to be related to Dozzle

Somebody recently added this FAQ https://dozzle.dev/guide/faq#my-dozzle-instances-are-timing-out-in-swarm-mode-or-i-m-not-seeing-all-my-swarm-nodes-when-behind-a-load-balancer-how-do-i-fix-it I wonder if that would fix it?

Going to convert this to discussion. I use traefik and swarm but not together so I am not sure.

[amir20]

Oh wait, you are using a proxy. AFAIK that won't work with swarm. See #3983.

[SolitudePy]

I'm not using swarm

[amir20]

Oh why did I think you were. Hmmm.. I am using traefik and Dozzle just fine. I never see this error.

Here is my yaml if it helps.

version: "3.8"

services:
  dozzle:
    deploy:
      labels:
        traefik.enable: 'true'
        traefik.http.routers.dozzle.rule: Host(`dozzle.xxx.com`)
        traefik.http.routers.dozzle.entrypoints: web
        traefik.http.routers.dozzle.middlewares: https_redirect

        traefik.http.routers.dozzlesecured.rule: Host(`dozzle.xxx.com`)
        traefik.http.routers.dozzlesecured.entrypoints: websecure
        traefik.http.routers.dozzlesecured.tls.certresolver: myresolver
        traefik.http.services.dozzlesecured.loadbalancer.server.port: 8080

        traefik.http.middlewares.https_redirect.redirectscheme.scheme: https
        traefik.http.middlewares.https_redirect.redirectscheme.permanent: 'true'
    image: amir20/dozzle:latest
    networks:
      - web
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
networks:
  web:
    external: true

I don't do anything special.

[amir20]

My hunch is that this is not related to traefik to Dozzle. It seems to be browser to traefik.

I would open network tab and check the error. That unexpected error is related to browser not being able to get a valid response. So I would check to see what kind of network error it might be.

Sorry I won't be able to help too much without actual error.

[SolitudePy]

could be

[amir20]

Yea, that would be it. That used to happen on my work laptop. It is VPN related I think. I was never able to figure it out.

[SolitudePy]

apparently, chromium-based browsers are notoriously aggressive with network monitoring, in my case I had flapping IPv6 addresses, chromium sees a change in the "network stack" and proactively kills all active sockets, including Dozzle's long-running log stream. disabling IPv6 or using Firefox fixed it for the time being.

[Jurrer]

I had exactly the opposite case where Firefox based browser was throwing this error when I was editing Notifications but chromium based browser didn't.
I did not spot any impact, config was saved.