# Configuration and domains

Environment variables, memory limits and custom domains.

> Section: Applications

## Environment variables

Configuration lives with the application resource. A change takes effect on the next deployment, because the container is immutable while it runs. Some variable names are blocked because they would let a tenant reach outside its own runtime.

## Memory

The configured memory value is a hard ceiling enforced by the kernel, with no swap. Set it from measured usage under load, not from optimism, and leave headroom for garbage collection spikes.

## Domains

An application is reachable at its platform hostname. Pointing your own domain at it is a DNS change plus a certificate issued on the server; the dashboard shows the current state rather than assuming success.