[Bug] Traefik (and dokploy) fails to start when port 8080 is already in use (Service Crash)

[zengdard]

To Reproduce

Have a service (in my case, CrowdSec) already listening on port 8080 (on 127.0.0.1:8080).
Go to the Dokploy Dashboard.
Navigate to Settings > Traefik.
Click to Install or Enable Traefik.
Observe the error in the logs or the UI behavior.

Current vs. Expected behavior

• Current behavior: When trying to enable Traefik, Docker throws a 500 error: Error: (HTTP code 500) server error - failed to set up container networking: ... failed to bind host port for 0.0.0.0:8080: ... address already in use

• The Traefik container fails to start or restarts in a loop. The Dokploy logs show repeated "ExecError" messages related to the port binding failure.
  Expected behavior: Dokploy should check if the required ports (specifically 8080 for the dashboard) are available before attempting to create the service. If the port is busy, it should display a clear user-friendly error message in the UI (e.g., "Port 8080 is already in use by [Service Name]. Please stop the service or change the Traefik configuration") instead of crashing or failing silently in the background.

Provide environment information

Operating System: Ubuntu 22.04 LTS ( (Vérifie avec lsb_release -a si ce n'est pas ça) )
Dokploy version: v0.27.1
VPS Provider: Hetzner (Cloud CX41 / 4GB)
What applications/services are you trying to deploy? Dokploy, Traefik, CrowdSec (Conflicting service).

Which area(s) are affected? (Select all that apply)

Application

Are you deploying the applications where Dokploy is installed or on a remote server?

Same server where Dokploy is installed

Additional context

I tested on a Hetzner Cloud VPS (Ubuntu).
The issue occurred because crowdsec was listening on 127.0.0.1:8080. Even though it was bound to localhost, Traefik (trying to bind 0.0.0.0:8080) failed.
Logs snippet:

Error [ExecError]: Command execution failed: Command failed: ...
Traefik Not Found: Starting Error: (HTTP code 500) server error - failed to set up container networking: ... failed to bind host port for 0.0.0.0:8080:172.21.0.10:8080/tcp: address already in use
Workaround: I had to manually stop the conflicting service (systemctl stop crowdsec), let Dokploy start Traefik, and then reconfigure the port mapping via CLI to free up port 8080 again.

Will you send a PR to fix it?

Yes

[zengdard]

Workaround used to fix the issue & secure the dashboard:

Since the UI crashed on port conflict, I had to fix it manually and then configure the dashboard as desired.

1. Resolving the address already in use (Port 8080):
The conflict was caused by crowdsec listening on 127.0.0.1:8080.

• Stopped the conflicting service: sudo systemctl stop crowdsec
• Initialized Traefik via the Dokploy UI (Install button).
• Once the Swarm service dokploy-traefik was created, I removed the conflicting port mapping via CLI:
  docker service update dokploy-traefik --publish-rm 8080:8080
• Restarted the conflicting service: sudo systemctl start crowdsec

2. Configuring Custom Subdomain & Password (Feature Request):
The UI doesn't currently allow setting a custom domain or password for the Traefik dashboard. I achieved this by editing the configuration files directly:

• Generated a password hash:
  htpasswd -nb admin mypassword
• Added BasicAuth Middleware:
  Edited /etc/dokploy/traefik/dynamic/middlewares.yml to add:

  traefik-auth:
    basicAuth:
      users:
        - "admin:$apr1$..." # Hash generated above

• Created a custom Router:
  Created /etc/dokploy/traefik/dynamic/dashboard.yml:

  http:
    routers:
      traefik-dashboard:
        rule: "Host(`traefik.domaine.fr`)"
        service: "api@internal" # Key for internal dashboard
        entryPoints:
          - "websecure"
        tls:
          certResolver: "letsencrypt"
        middlewares:
          - "traefik-auth"

• Secured the API:
  Edited /etc/dokploy/traefik/traefik.yml: set api.insecure: false.
• Closed the backdoor:
  Removed port 8080 exposure from the Docker service to ensure access is only allowed via the secured domain.

Suggestion: It would be great if the "Settings > Traefik" page in Dokploy allowed:

1. Specifying a custom domain for the dashboard.
2. Setting a username/password directly in the UI.
3. Automatically generating the dashboard.yml and middlewares.yml files.

[Siumauricio]

We already have this validation, doing the same steps you shared above it throws the error...

[zengdard]

1. Port Conflict (Host Service, not Container):
   The crash happened immediately when I clicked "Install/Start" in the Dokploy UI.
   The issue was not caused by another Docker container, but by a system service installed directly on the host (crowdsec), which was already listening on port 127.0.0.1:8080. Dokploy tried to bind the host port 8080 without checking if it was occupied by a non-Docker service, resulting in an instant 500 error.

Workaround:
I had to manually stop the system service (sudo systemctl stop crowdsec) to free the port, initialize Traefik, and then reconfigure the Docker service port mapping to resolve the conflict.

2. Dashboard Configuration:
   To add a custom domain (e.g., traefik.gofin.fr) and password protection to the Traefik dashboard, it is currently not possible via the UI. I had to manually modify the configuration files.
   This involved editing traefik.yml to disable the insecure API to route the custom domain and set up the BasicAuth middleware.

Suggestion:
Please add a pre-flight check for host-level port usage before starting Traefik. Also, it would be very helpful to have an option in the UI to configure a custom domain and password for the Traefik dashboard automatically, rather than requiring manual file editing.

Do you want a PR for this ?