Merge pull request #1834 from Roasbeef/rfq-keep-alive

rfq+server: properly configure gRPC keep alive settings for client+server

Author: ffranr

docs/examples/basic-price-oracle/main.go

@@ -29,6 +29,7 @@ import (
 	"github.com/sirupsen/logrus"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/keepalive"
 )
 
 const (
@@ -455,11 +456,44 @@ func main() {
 		log.Fatalf("Failed to generate TLS certificate: %v", err)
 	}
 
-	// Create the gRPC server with TLS
+	// Configure server-side keepalive parameters. These settings ensure the
+	// server actively probes client connection health and allows long-lived
+	// idle connections.
+	serverKeepalive := keepalive.ServerParameters{
+		// Ping clients after 1 minute of inactivity.
+		Time: time.Minute,
+
+		// Wait 20 seconds for ping response.
+		Timeout: 20 * time.Second,
+
+		// Allow connections to stay idle for 24 hours. The active
+		// pinging mechanism (via Time parameter) handles health
+		// checking, so we don't need aggressive idle timeouts.
+		MaxConnectionIdle: time.Hour * 24,
+	}
+
+	// Configure client keepalive enforcement policy. This tells the server
+	// how to handle client keepalive pings.
+	clientKeepalive := keepalive.EnforcementPolicy{
+		// Allow client to ping even when there are no active RPCs.
+		// This is critical for long-lived connections with infrequent
+		// price queries.
+		PermitWithoutStream: true,
+
+		// Prevent abusive clients from pinging too frequently (DoS
+		// protection).
+		MinTime: 5 * time.Second,
+	}
+
+	// Create the gRPC server with TLS and keepalive configuration.
 	transportCredentials := credentials.NewTLS(&tls.Config{
 		Certificates: []tls.Certificate{tlsCert},
 	})
-	backendService := grpc.NewServer(grpc.Creds(transportCredentials))
+	backendService := grpc.NewServer(
+		grpc.Creds(transportCredentials),
+		grpc.KeepaliveParams(serverKeepalive),
+		grpc.KeepaliveEnforcementPolicy(clientKeepalive),
+	)
 
 	err = startService(backendService)
 	if err != nil {

docs/release-notes/release-notes-0.7.0.md

@@ -63,6 +63,18 @@
   dirty. This issue has been resolved, and the behavior is now consistent across
   all database backend types.
 
+- [Fixed "connection reset by peer" errors in RFQ price oracle
+  connections](https://github.com/lightninglabs/taproot-assets/pull/1834) by
+  implementing comprehensive bidirectional gRPC keepalive configuration. The
+  issue occurred when connections sat idle between RFQ price queries and were
+  silently closed by the network layer or server timeout, causing the first
+  payment attempt after an idle period to fail. The fix adds client-side
+  keepalive pings every 30 seconds and extends the server's idle connection
+  timeout from 2 minutes to 24 hours, while enabling active health checking on
+  both sides. This ensures connections remain alive during infrequent RFQ
+  operations and any network issues are detected promptly rather than
+  discovered only when the next RPC fails.
+
 # New Features
 
 ## Functional Enhancements

rfq/oracle.go

@@ -18,6 +18,7 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/keepalive"
 )
 
 // PriceQueryIntent is an enum that represents the intent of a price rate
@@ -186,16 +187,38 @@ type RpcPriceOracle struct {
 	rawConn *grpc.ClientConn
 }
 
+// clientKeepaliveDialOption configures bidirectional health probing to prevent
+// idle RFQ connections from being silently terminated by network intermediaries
+// (NATs, load balancers) or aggressive server timeouts. Without active
+// keepalive, the first price query after an idle period would fail with
+// "connection reset by peer" and require a retry.
+var clientKeepaliveDialOption = grpc.WithKeepaliveParams(
+	keepalive.ClientParameters{
+		// Ping server after 30 seconds of inactivity.
+		Time: 30 * time.Second,
+
+		// Wait 20 seconds for ping response.
+		Timeout: 20 * time.Second,
+
+		// Permit keepalive pings even when there are no active
+		// streams. This is critical for long-lived connections with
+		// infrequent RFQ requests.
+		PermitWithoutStream: true,
+	},
+)
+
 // serverDialOpts returns the set of server options needed to connect to the
 // price oracle RPC server using a TLS connection.
 func serverDialOpts() ([]grpc.DialOption, error) {
 	var opts []grpc.DialOption
 
-	// Skip TLS certificate verification.
 	tlsConfig := tls.Config{InsecureSkipVerify: true}
 	transportCredentials := credentials.NewTLS(&tlsConfig)
+
 	opts = append(opts, grpc.WithTransportCredentials(transportCredentials))
 
+	opts = append(opts, clientKeepaliveDialOption)
+
 	return opts, nil
 }
 
@@ -209,6 +232,8 @@ func insecureServerDialOpts() ([]grpc.DialOption, error) {
 		insecure.NewCredentials(),
 	))
 
+	opts = append(opts, clientKeepaliveDialOption)
+
 	return opts, nil
 }
 

server.go

@@ -370,11 +370,34 @@ func (s *Server) RunUntilShutdown(mainErrChan <-chan error) error {
 	serverOpts = append(serverOpts, rpcServerOpts...)
 	serverOpts = append(serverOpts, ServerMaxMsgReceiveSize)
 
-	keepAliveParams := keepalive.ServerParameters{
-		MaxConnectionIdle: time.Minute * 2,
-	}
-
-	serverOpts = append(serverOpts, grpc.KeepaliveParams(keepAliveParams))
+	// Configure server-side keepalive parameters. These settings allow the
+	// server to actively probe the connection health and ensure connections
+	// stay alive during idle periods.
+	serverKeepalive := keepalive.ServerParameters{
+		// Ping client after 1 minute of inactivity.
+		Time: time.Minute,
+		// Wait 20 seconds for ping response.
+		Timeout: 20 * time.Second,
+		// Allow connections to remain idle for extended periods. This
+		// is particularly important for RFQ operations where price
+		// oracle connections may be idle for long periods.
+		MaxConnectionIdle: time.Hour * 24,
+	}
+
+	// Configure client enforcement policy. This allows clients to send
+	// keepalive pings even when there are no active streams, which is
+	// crucial for long-lived connections with infrequent activity.
+	clientKeepalive := keepalive.EnforcementPolicy{
+		// Minimum time between client pings.
+		MinTime: 5 * time.Second,
+		// Allow pings without active RPCs.
+		PermitWithoutStream: true,
+	}
+
+	serverOpts = append(
+		serverOpts, grpc.KeepaliveParams(serverKeepalive),
+		grpc.KeepaliveEnforcementPolicy(clientKeepalive),
+	)
 
 	grpcServer := grpc.NewServer(serverOpts...)
 	defer grpcServer.Stop()