Problem Description

When using theworkspace_expose_port function in Blink to expose port 3000 for a Next.js development server, the generated URL returns a502 Bad Gateway error from Koyeb.

Environment Details

• Platform: Koyeb Container workspace
• Application: Next.js 15.3.3 documentation website
• Port: 3000
• Generated URL:https://3000-53efb5e2-adb5-4fea-9eb2-a6ca69a39f4c.build.party
• Error: 502 Bad Gateway

Steps to Reproduce

1. Initialize a workspace usingworkspace_initialize
2. Create and run a Next.js application on port 3000
3. Useworkspace_expose_port with port 3000
4. Navigate to the generated URL
5. Observe 502 Bad Gateway error

Expected Behavior

The exposed URL should successfully proxy requests to the running Next.js development server and display the application.

Actual Behavior

The URL returns a 502 Bad Gateway error, indicating that Koyeb cannot reach the backend service.

Additional Context

• Chat Reference: This issue was discovered during a documentation website build session
• Development Server: The Next.js dev server was running successfully locally (npm run dev showed "Ready in 1287ms")
• Workspace Status: The workspace appears to have been reset between the port exposure and URL access
• Console Output: Development server showed no errors when initially started

Technical Details

The development server was started with:

npm run dev

And showed successful startup:

▲ Next.js 15.3.3- Local:        http://localhost:3000- Network:      http://10.33.229.177:3000✓ Ready in 1287ms

However, when accessing the exposed URL, Koyeb returns a 502 error, suggesting either:

1. The port forwarding/proxy configuration is incorrect
2. The workspace container networking is not properly configured
3. The service discovery mechanism is failing

Potential Root Causes

1. Network Configuration: Koyeb proxy unable to reach the container's port 3000
2. Service Discovery: The exposed port mechanism not properly registering the service
3. Container Lifecycle: Workspace reset causing the service to become unavailable
4. Port Binding: Next.js server not binding to the correct interface for external access

Requested Investigation

@mattvollmer@kylecarbs Could you please investigate:

1. The Koyeb container networking configuration for exposed ports
2. Whether there are specific requirements for how services should bind to ports
3. If there are logs available from the Koyeb side showing the proxy attempts
4. Whether workspace resets affect exposed port functionality

Workaround Needed

Currently, there's no reliable way to expose running services from Blink workspaces, which limits the ability to demonstrate web applications and APIs to users.

Labels: bug, networking, koyeb, workspace
Priority: High - affects core functionality of workspace port exposure