Set keep-alive for tcp connections

utils/init_tcp.go

 import (
 	"fmt"
 	"net"
+	"time"
 
 	"github.com/9seconds/mtg/config"
 )
 
+const tcpKeepAlivePingPeriod = 2 * time.Second
+
 func InitTCP(conn net.Conn) error {
 	tcpConn := conn.(*net.TCPConn)
 
 		return fmt.Errorf("cannot set write buffer size: %w", err)
 	}
 
+	if err := tcpConn.SetKeepAlive(true); err != nil {
+		return fmt.Errorf("cannot enable keep-alive: %w", err)
+	}
+
+	if err := tcpConn.SetKeepAlivePeriod(tcpKeepAlivePingPeriod); err != nil {
+		return fmt.Errorf("cannot set keep-alive period: %w", err)
+	}
+
 	return nil
 }