feat: invalid keep-alive settings are a warning now (#856)

Instead of crashing, invalid TCP keep-alive settings produce a warning
now.

Author: levkk

pgdog-config/src/networking.rs

@@ -100,7 +100,7 @@ impl std::fmt::Display for Tcp {
             if let Some(ref c) = self.congestion_control {
                 c.as_str()
             } else {
-                ""
+                "default"
             },
         )
     }

pgdog/src/backend/server.rs

@@ -90,12 +90,18 @@ impl Server {
     ) -> Result<Self, Error> {
         debug!("=> {}", addr);
         let stream = TcpStream::connect(addr.addr().await?).await?;
-        tweak(&stream)?;
-        let cfg = config();
+        let config = config();
 
-        let mut stream = Stream::plain(stream, cfg.config.memory.net_buffer);
+        if let Err(err) = tweak(&stream, &config.config.tcp) {
+            warn!(
+                "keepalive settings ({}) are not supported on this system, ignoring, error: {} [{}]",
+                config.config.tcp, err, addr,
+            );
+        }
+
+        let mut stream = Stream::plain(stream, config.config.memory.net_buffer);
 
-        let tls_mode = cfg.config.general.tls_verify;
+        let tls_mode = config.config.general.tls_verify;
 
         // Only attempt TLS if not in Disabled mode
         if tls_mode != TlsVerifyMode::Disabled {
@@ -117,7 +123,7 @@ impl Server {
 
                 let connector = connector_with_verify_mode(
                     tls_mode,
-                    cfg.config.general.tls_server_ca_certificate.as_ref(),
+                    config.config.general.tls_server_ca_certificate.as_ref(),
                 )?;
                 let plain = stream.take()?;
 
@@ -128,7 +134,7 @@ impl Server {
                     Ok(tls_stream) => {
                         debug!("TLS handshake successful with {}", addr.host);
                         let cipher = tokio_rustls::TlsStream::Client(tls_stream);
-                        stream = Stream::tls(cipher, cfg.config.memory.net_buffer);
+                        stream = Stream::tls(cipher, config.config.memory.net_buffer);
                     }
                     Err(e) => {
                         error!("TLS handshake failed with {:?} [{}]", e, addr);
@@ -260,7 +266,7 @@ impl Server {
             addr: addr.clone(),
             stream: Some(stream),
             id,
-            stats: Stats::connect(id, addr, &params, &options, &cfg.config.memory),
+            stats: Stats::connect(id, addr, &params, &options, &config.config.memory),
             replication_mode: options.replication_mode(),
             params,
             changed_params: Parameters::default(),
@@ -275,7 +281,7 @@ impl Server {
             re_synced: false,
             sending_request: false,
             pooler_mode: PoolerMode::Transaction,
-            stream_buffer: MessageBuffer::new(cfg.config.memory.message_buffer),
+            stream_buffer: MessageBuffer::new(config.config.memory.message_buffer),
             disconnect_reason: None,
         };
 

pgdog/src/frontend/listener.rs

@@ -154,9 +154,17 @@ impl Listener {
     }
 
     async fn handle_client(stream: TcpStream, addr: SocketAddr) -> Result<(), Error> {
-        tweak(&stream)?;
         let config = config();
 
+        // Not the end of the world if the tweaks are
+        // not applied.
+        if let Err(err) = tweak(&stream, &config.config.tcp) {
+            warn!(
+                "keepalive settings ({}) are not supported on this system, ignoring, error: {} [{}]",
+                config.config.tcp, err, addr
+            );
+        }
+
         let mut stream = Stream::plain(stream, config.config.memory.net_buffer);
 
         let tls = acceptor();

pgdog/src/net/tweaks.rs

@@ -1,14 +1,10 @@
 use std::io::Result;
 
+use pgdog_config::Tcp;
 use socket2::{SockRef, TcpKeepalive};
 use tokio::net::TcpStream;
 
-use crate::config::config;
-
-pub fn tweak(socket: &TcpStream) -> Result<()> {
-    let config = config();
-    let config = &config.config.tcp;
-
+pub fn tweak(socket: &TcpStream, config: &Tcp) -> Result<()> {
     // Disable the Nagle algorithm.
     socket.set_nodelay(true)?;