DL104 Proxy loop

508. The proxy adds the route’s hostname to x-devlanes-via on every request it forwards. A request that arrives with its own route’s hostname in that header has come back from the service, and forwarding it again would never end.

A dev server proxy or rewrite sends requests to devlanes, for example to http://localhost or the app’s own https:// URL, and keeps the original Host header, so the proxy routes them to the same service. Vite server.proxy without changeOrigin and Next.js rewrites to the app’s own URL do this. Forwarding to a different devlanes hostname is not a loop.

Point the proxy at the target service’s port. ${{ services.api.port }} in devlanes.yaml gives a service another service’s port:

services:
  web:
    run_script: { file: package.json, name: dev }
    env:
      API_URL: "http://127.0.0.1:${{ services.api.port }}"

server: { proxy: { '/api': process.env.API_URL } }

If the target has to stay a devlanes hostname, rewrite Host to it (Vite changeOrigin: true). See ports and environment.