Private Networking

Apps and add-ons in the same phase talk over the private network. Attach them on the canvas — there is no private-DNS settings page.

Same-phase attach

From the phase canvas, connect a database or other add-on to the app (or add it from the app Add-ons tab). Connected apps get the add-on’s connection variables injected on the Variables tab. Commit those changes on the canvas so the app restarts with the new values.

Reach a sibling app

Use the other app’s name as the hostname (the name you gave it when you created it). There is no extra DNS form to fill in.

# Web API named "api"
http://api:8080

# Worker named "background-worker"
http://background-worker:3000

Listen on the port from PORT (default 8080) unless you changed it on Settings.

Add-on connection strings

Prefer the injected variables after you attach — they include host, port, and credentials. Typical ports if you assemble a URL yourself:

• •PostgreSQL: 5432
• •MySQL / MariaDB: 3306
• •Redis / Valkey: 6379
• •MongoDB: 27017

Example: API calling a worker

const response = await fetch('http://worker:3000/process', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ jobId: '123', payload: data }),
})

const result = await response.json()

Who can reach what

Private traffic stays inside the phase. Another project cannot use these hostnames. For a public caller, use the app’s *.stackblaze.app URL (or a custom domain) and authenticate in your app.