render-web-services

Render Web Services

This skill covers Web Service behavior on Render: how traffic reaches your process, how deploys go live, and how optional features (domains, disks, auto-deploy) interact. Use it alongside Blueprint and networking skills when wiring render.yaml or Dashboard settings.

When to Use

• Configuring or debugging port binding, PORT, or multi-port web services
• TLS/HTTPS expectations at the edge vs inside the container
• Health checks blocking or rolling back deploys
• Custom domains, DNS, and certificate provisioning
• Auto-deploy, CI-gated deploys, and PR preview generation
• Persistent disks and their impact on scaling and zero-downtime
• Deploy lifecycle: build, pre-deploy, swap, drain, rollback, shutdown delay

Deeper patterns live under references/ (health checks, domains, deploy phases).

Port Binding

• Listen on 0.0.0.0 (all interfaces). Binding only to localhost or 127.0.0.1 prevents Render’s proxy from reaching your app.
• Use the PORT environment variable for the HTTP listen port. Render sets it for you; the default is often 10000 and you can change the configured value in the service Settings in the Dashboard.
• Reserved ports (do not bind your application to these for normal traffic): 18012, 18013, 19099.

Multi-port Web Services

• Only one port receives public HTTP traffic: the port aligned with PORT.
• Additional open ports are reachable on Render’s private network only (not from the public internet through the same public URL pattern).

TLS and HTTPS

• TLS terminates at Render’s edge. The edge speaks HTTPS to clients; your process typically receives plain HTTP on PORT.
• HTTPS redirect for clients is handled by the platform; users hitting HTTP are redirected appropriately at the edge.
• Do not terminate TLS inside the app for the primary public listener unless you have a rare, explicit need—standard Web Services assume HTTP behind the proxy.