Caddy Frontend & Backend Reverse Proxy

Combine your separate frontend and backend services into one domain!

View the example public project here

Access the frontend from /* and access the backend from /api/* on the same domain

Frontend - React: https://mysite.up.railway.app/

Backend - FastAPI: https://mysite.up.railway.app/api/

The proxy configurations are done in the Caddyfile everything is commented for your ease of use!

When deploying your Reverse Proxy service it will require you to set two service variables: FRONTEND_HOST and BACKEND_HOST

Note: You will first need to have set a fixed PORT variable in both the frontend and backend services before deploying this template

These are the two template variables that you will be required to fill out during the first deployment of this service, replace the respective <frontend service name> and <backend service name> with the service names as they appear in the Railway project view

FRONTEND_HOST = ${{<frontend service name>.RAILWAY_PRIVATE_DOMAIN}}:${{<frontend service name>.PORT}}
BACKEND_HOST = ${{<backend service name>.RAILWAY_PRIVATE_DOMAIN}}:${{<backend service name>.PORT}}

Relevant Caddy documentation:

• The Caddyfile
• Caddyfile Directives
• reverse_proxy

Some prerequisites to help with common issues that could arise:

• Both the frontend and backend need to listen on fixed ports, in my Caddyfile I have used port 3000 in the proxy address, and configured my frontend and backend to both listen on port 3000

  • This can be done by configuring your frontend and backend apps to listen on the $PORT environment variable, then setting a PORT service variable to 3000

• Since Railway's internal network is IPv6 only the frontend and backend apps will need to listen on :: (all interfaces - both IPv4 and IPv6)

  Start commands for some popular frameworks:

  • Gunicorn: gunicorn main:app -b [::]:$PORT

  • Uvicorn: uvicorn main:app --host :: --port $PORT

    • Uvicorn does not support dual stack binding (IPv6 and IPv4) from the CLI, so while that start command will work to enable access from within the private network, this prevents you from accessing the app from the public domain if needed, I recommend using Hypercorn instead

  • Hypercorn: hypercorn main:app --bind [::]:$PORT

  • Next: next start -H :: --port $PORT

  • Express/Nest: app.listen(process.env.PORT, "::");