client,server: Expose reuse-port and reuse-address so they can be

configured via a config file.

client/pkg/transport/sockopt.go

@@ -21,12 +21,12 @@ type SocketOpts struct {
 	// in which case lock on data file could result in unexpected
 	// condition. User should take caution to protect against lock race.
 	// [1] https://man7.org/linux/man-pages/man7/socket.7.html
-	ReusePort bool
+	ReusePort bool `json:"reuse-port"`
 	// ReuseAddress enables a socket option SO_REUSEADDR which allows
 	// binding to an address in `TIME_WAIT` state. Useful to improve MTTR
 	// in cases where etcd slow to restart due to excessive `TIME_WAIT`.
 	// [1] https://man7.org/linux/man-pages/man7/socket.7.html
-	ReuseAddress bool
+	ReuseAddress bool `json:"reuse-address"`
 }
 
 func getControls(sopts *SocketOpts) Controls {

server/embed/config.go

@@ -252,7 +252,7 @@ type Config struct {
 	GRPCKeepAliveTimeout time.Duration `json:"grpc-keepalive-timeout"`
 
 	// SocketOpts are socket options passed to listener config.
-	SocketOpts transport.SocketOpts
+	SocketOpts transport.SocketOpts `json:"socket-options"`
 
 	// PreVote is true to enable Raft Pre-Vote.
 	// If enabled, Raft runs an additional election phase
@@ -449,7 +449,10 @@ func NewConfig() *Config {
 		GRPCKeepAliveInterval: DefaultGRPCKeepAliveInterval,
 		GRPCKeepAliveTimeout:  DefaultGRPCKeepAliveTimeout,
 
-		SocketOpts: transport.SocketOpts{},
+		SocketOpts: transport.SocketOpts{
+			ReusePort:    false,
+			ReuseAddress: false,
+		},
 
 		TickMs:                     100,
 		ElectionMs:                 1000,