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Internal Networking

Internal container port​

The internal container port is the port on which your application listens for incoming traffic inside the project. QuickStack uses this port for:

  • Routing external traffic from a domain to the correct container port.
  • Enabling service-to-service communication between apps in the same project.

Default: Usually 80 or 3000 depending on the application image.

Changing the port​

  1. Open your app and go to the Domains tab.
  2. Locate the Internal Port section.
  3. Click the edit icon and enter the new port number.
  4. Click Save, then Deploy.
Redeployment required

Changing the internal port requires a redeployment to take effect.

Service-to-service communication​

Apps within the same project communicate using internal hostnames. These hostnames are only routable within the project's network namespace — they are not publicly accessible unless you explicitly add a domain.

Finding internal hostnames​

Open the target app's Domains tab → scroll to Internal Hostnames. You'll see entries like:

svc-app-xyz

Example connection strings​

# PostgreSQL
DATABASE_URL=postgres://user:password@svc-app-xyz:5432/database

# Redis
REDIS_URL=redis://svc-app-abc:6379

# Internal HTTP service
API_BASE_URL=http://svc-app-def:3000

Set these as environment variables in your app, then deploy.

Common use cases​

  • Connecting apps to databases (most common)
  • Microservice architectures — backend services that should not be publicly accessible
  • Sidecar apps (e.g. a proxy or cache layer)