feat(proxy): track SNI usage by protocol, including for http (#11863)

## Problem

We want to see how many users of the legacy serverless driver are still
using the old URL for SQL-over-HTTP traffic.

## Summary of changes

Adds a protocol field to the connections_by_sni metric. Ensures it's
incremented for sql-over-http.

proxy/src/auth/credentials.rs

@@ -12,9 +12,9 @@ use tracing::{debug, warn};
 use crate::auth::password_hack::parse_endpoint_param;
 use crate::context::RequestContext;
 use crate::error::{ReportableError, UserFacingError};
-use crate::metrics::{Metrics, SniKind};
+use crate::metrics::{Metrics, SniGroup, SniKind};
 use crate::proxy::NeonOptions;
-use crate::serverless::SERVERLESS_DRIVER_SNI;
+use crate::serverless::{AUTH_BROKER_SNI, SERVERLESS_DRIVER_SNI};
 use crate::types::{EndpointId, RoleName};
 
 #[derive(Debug, Error, PartialEq, Eq, Clone)]
@@ -65,7 +65,7 @@ pub(crate) fn endpoint_sni(sni: &str, common_names: &HashSet<String>) -> Option<
     if !common_names.contains(common_name) {
         return None;
     }
-    if subdomain == SERVERLESS_DRIVER_SNI {
+    if subdomain == SERVERLESS_DRIVER_SNI || subdomain == AUTH_BROKER_SNI {
         return None;
     }
     Some(EndpointId::from(subdomain))
@@ -128,22 +128,23 @@ impl ComputeUserInfoMaybeEndpoint {
 
         let metrics = Metrics::get();
         debug!(%user, "credentials");
-        if sni.is_some() {
+
+        let protocol = ctx.protocol();
+        let kind = if sni.is_some() {
             debug!("Connection with sni");
-            metrics.proxy.accepted_connections_by_sni.inc(SniKind::Sni);
+            SniKind::Sni
         } else if endpoint.is_some() {
-            metrics
-                .proxy
-                .accepted_connections_by_sni
-                .inc(SniKind::NoSni);
             debug!("Connection without sni");
+            SniKind::NoSni
         } else {
-            metrics
-                .proxy
-                .accepted_connections_by_sni
-                .inc(SniKind::PasswordHack);
             debug!("Connection with password hack");
-        }
+            SniKind::PasswordHack
+        };
+
+        metrics
+            .proxy
+            .accepted_connections_by_sni
+            .inc(SniGroup { protocol, kind });
 
         let options = NeonOptions::parse_params(params);
 

proxy/src/metrics.rs

@@ -115,8 +115,8 @@ pub struct ProxyMetrics {
     #[metric(metadata = Thresholds::with_buckets([0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 10.0, 20.0, 50.0, 100.0]))]
     pub allowed_vpc_endpoint_ids: Histogram<10>,
 
-    /// Number of connections (per sni).
-    pub accepted_connections_by_sni: CounterVec<StaticLabelSet<SniKind>>,
+    /// Number of connections, by the method we used to determine the endpoint.
+    pub accepted_connections_by_sni: CounterVec<SniSet>,
 
     /// Number of connection failures (per kind).
     pub connection_failures_total: CounterVec<StaticLabelSet<ConnectionFailureKind>>,
@@ -342,11 +342,20 @@ pub enum LatencyExclusions {
     ClientCplaneComputeRetry,
 }
 
+#[derive(LabelGroup)]
+#[label(set = SniSet)]
+pub struct SniGroup {
+    pub protocol: Protocol,
+    pub kind: SniKind,
+}
+
 #[derive(FixedCardinalityLabel, Copy, Clone)]
-#[label(singleton = "kind")]
 pub enum SniKind {
+    /// Domain name based routing. SNI for libpq/websockets. Host for HTTP
     Sni,
+    /// Metadata based routing. `options` for libpq/websockets. Header for HTTP
     NoSni,
+    /// Metadata based routing, using the password field.
     PasswordHack,
 }
 

proxy/src/serverless/mod.rs

@@ -56,6 +56,7 @@ use crate::serverless::backend::PoolingBackend;
 use crate::serverless::http_util::{api_error_into_response, json_response};
 
 pub(crate) const SERVERLESS_DRIVER_SNI: &str = "api";
+pub(crate) const AUTH_BROKER_SNI: &str = "apiauth";
 
 pub async fn task_main(
     config: &'static ProxyConfig,

proxy/src/serverless/sql_over_http.rs

@@ -38,7 +38,7 @@ use crate::config::{AuthenticationConfig, HttpConfig, ProxyConfig, TlsConfig};
 use crate::context::RequestContext;
 use crate::error::{ErrorKind, ReportableError, UserFacingError};
 use crate::http::{ReadBodyError, read_body_with_limit};
-use crate::metrics::{HttpDirection, Metrics};
+use crate::metrics::{HttpDirection, Metrics, SniGroup, SniKind};
 use crate::proxy::{NeonOptions, run_until_cancelled};
 use crate::serverless::backend::HttpConnError;
 use crate::types::{DbName, RoleName};
@@ -227,6 +227,32 @@ fn get_conn_info(
         }
     }
 
+    // check the URL that was used, for metrics
+    {
+        let host_endpoint = headers
+            // get the host header
+            .get("host")
+            // extract the domain
+            .and_then(|h| {
+                let (host, _port) = h.to_str().ok()?.split_once(':')?;
+                Some(host)
+            })
+            // get the endpoint prefix
+            .map(|h| h.split_once('.').map_or(h, |(prefix, _)| prefix));
+
+        let kind = if host_endpoint == Some(&*endpoint) {
+            SniKind::Sni
+        } else {
+            SniKind::NoSni
+        };
+
+        let protocol = ctx.protocol();
+        Metrics::get()
+            .proxy
+            .accepted_connections_by_sni
+            .inc(SniGroup { protocol, kind });
+    }
+
     ctx.set_user_agent(
         headers
             .get(hyper::header::USER_AGENT)

test_runner/fixtures/neon_fixtures.py

@@ -3835,7 +3835,7 @@ class NeonAuthBroker:
         external_http_port: int,
         auth_backend: NeonAuthBroker.ProxyV1,
     ):
-        self.domain = "apiauth.local.neon.build"  # resolves to 127.0.0.1
+        self.domain = "local.neon.build"  # resolves to 127.0.0.1
         self.host = "127.0.0.1"
         self.http_port = http_port
         self.external_http_port = external_http_port
@@ -3852,7 +3852,7 @@ class NeonAuthBroker:
         # generate key of it doesn't exist
         crt_path = self.test_output_dir / "proxy.crt"
         key_path = self.test_output_dir / "proxy.key"
-        generate_proxy_tls_certs("apiauth.local.neon.build", key_path, crt_path)
+        generate_proxy_tls_certs(f"apiauth.{self.domain}", key_path, crt_path)
 
         args = [
             str(self.neon_binpath / "proxy"),
@@ -3896,10 +3896,10 @@ class NeonAuthBroker:
 
         log.info(f"Executing http query: {query}")
 
-        connstr = f"postgresql://{user}@{self.domain}/postgres"
+        connstr = f"postgresql://{user}@ep-foo-bar-1234.{self.domain}/postgres"
         async with httpx.AsyncClient(verify=str(self.test_output_dir / "proxy.crt")) as client:
             response = await client.post(
-                f"https://{self.domain}:{self.external_http_port}/sql",
+                f"https://apiauth.{self.domain}:{self.external_http_port}/sql",
                 json={"query": query, "params": args},
                 headers={
                     "Neon-Connection-String": connstr,