fix(server): Bind exclusively to the port (#2582)

Bind eagerly (and exclusively) to the port for the HTTP server, and fail
to start the Relay otherwise.

The proper error should be also provided, e.g.

```
ERROR relay_server::actors::server: Failed to start the HTTP server: Address already in use (os error 48)
```

CHANGELOG.md

@@ -15,6 +15,7 @@
 - Fix reporting of Relay's crashes to Sentry. The `crash-handler` feature did not enable the crash reporter and uploads of crashes were broken. ([#2532](https://github.com/getsentry/relay/pull/2532))
 - Use correct field to pick SQL parser for span normalization. ([#2536](https://github.com/getsentry/relay/pull/2536))
 - Prevent stack overflow on SQL serialization. ([#2538](https://github.com/getsentry/relay/pull/2538))
+- Bind exclusively to the port for the HTTP server. ([#2582](https://github.com/getsentry/relay/pull/2582))
 
 **Internal**:
 

relay-server/src/actors/server.rs

@@ -1,4 +1,4 @@
-use std::net::SocketAddr;
+use std::net::{SocketAddr, TcpListener};
 use std::sync::Arc;
 use std::time::Duration;
 
@@ -111,15 +111,24 @@ impl Service for HttpServer {
  .build();
 
  let handle = Handle::new();
- let server = axum_server::bind(config.listen_addr())
- .http_config(http_config)
- .addr_incoming_config(addr_config)
- .handle(handle.clone());
-
- relay_log::info!("spawning http server");
- relay_log::info!(" listening on http://{}/", config.listen_addr());
- relay_statsd::metric!(counter(RelayCounters::ServerStarting) += 1);
- tokio::spawn(server.serve(app));
+ match TcpListener::bind(config.listen_addr()) {
+ Ok(listener) => {
+ listener.set_nonblocking(true).ok();
+ let server = axum_server::from_tcp(listener)
+ .http_config(http_config)
+ .addr_incoming_config(addr_config)
+ .handle(handle.clone());
+
+ relay_log::info!("spawning http server");
+ relay_log::info!(" listening on http://{}/", config.listen_addr());
+ relay_statsd::metric!(counter(RelayCounters::ServerStarting) += 1);
+ tokio::spawn(server.serve(app));
+ }
+ Err(err) => {
+ relay_log::error!("Failed to start the HTTP server: {err}");
+ std::process::exit(1);
+ }
+ }
 
  tokio::spawn(async move {
  let Shutdown { timeout } = Controller::shutdown_handle().notified().await;