Proxy added per ep rate limiter (#7636)

## Problem

There is no global per-ep rate limiter in proxy.

## Summary of changes

* Return global per-ep rate limiter back.
* Rename weak compute rate limiter (the cli flags were not used
anywhere, so it's safe to rename).

proxy/src/serverless/backend.rs

@@ -16,6 +16,7 @@ use crate::{
     context::RequestMonitoring,
     error::{ErrorKind, ReportableError, UserFacingError},
     proxy::{connect_compute::ConnectMechanism, retry::ShouldRetry},
+    rate_limiter::EndpointRateLimiter,
     Host,
 };
 
@@ -24,6 +25,7 @@ use super::conn_pool::{poll_client, Client, ConnInfo, GlobalConnPool};
 pub struct PoolingBackend {
     pub pool: Arc<GlobalConnPool<tokio_postgres::Client>>,
     pub config: &'static ProxyConfig,
+    pub endpoint_rate_limiter: Arc<EndpointRateLimiter>,
 }
 
 impl PoolingBackend {
@@ -39,6 +41,12 @@ impl PoolingBackend {
         if !check_peer_addr_is_in_list(&ctx.peer_addr, &allowed_ips) {
             return Err(AuthError::ip_address_not_allowed(ctx.peer_addr));
         }
+        if !self
+            .endpoint_rate_limiter
+            .check(conn_info.user_info.endpoint.clone().into(), 1)
+        {
+            return Err(AuthError::too_many_connections());
+        }
         let cached_secret = match maybe_secret {
             Some(secret) => secret,
             None => backend.get_role_secret(ctx).await?,

proxy/src/serverless/websocket.rs

@@ -5,6 +5,7 @@ use crate::{
     error::{io_error, ReportableError},
     metrics::Metrics,
     proxy::{handle_client, ClientMode},
+    rate_limiter::EndpointRateLimiter,
 };
 use bytes::{Buf, Bytes};
 use futures::{Sink, Stream};
@@ -134,6 +135,7 @@ pub async fn serve_websocket(
     mut ctx: RequestMonitoring,
     websocket: HyperWebsocket,
     cancellation_handler: Arc<CancellationHandlerMain>,
+    endpoint_rate_limiter: Arc<EndpointRateLimiter>,
     hostname: Option<String>,
 ) -> anyhow::Result<()> {
     let websocket = websocket.await?;
@@ -148,6 +150,7 @@ pub async fn serve_websocket(
         cancellation_handler,
         WebSocketRw::new(websocket),
         ClientMode::Websockets { hostname },
+        endpoint_rate_limiter,
         conn_gauge,
     )
     .await;