NGINX alternatives: migrate behavior with traffic tests

For NGINX alternatives, inventory the actual proxy and web-server behavior before translating configuration.

• Recreate TLS, redirects, caching, compression, headers, and upstream routing.
• Test WebSockets, large uploads, timeouts, and client IP forwarding.
• Run load tests and compare latency and resource use.
• Simulate an upstream failure and inspect retries, error pages, and logs.
• Keep a rollback route and validate certificates before cutover.

A config file that parses is not proof of equivalent routing or security. Use request-level tests for each important path.