Creates only one adapter on startup based on flags

When the server is starting up, an adapter is created based on command
line flags. Removed the adapter creation related API from protobuf. The
adapter is shared by all enforcers.

Change-Id: I2d399973c19caf31183078f36f400dfc2d3272b7
Signed-off-by: Loïc Collignon <loic.collignon@iot.bzh>

main.go

@@ -30,19 +30,29 @@ import (
 
 func main() {
 	var port int
+	var driverName string
+	var connectionString string
+	var dbSpecified bool
 	flag.IntVar(&port, "port", 50051, "listening port")
+	flag.StringVar(&driverName, "driver", "postgres", "adapter's driver (can be 'file', 'mysql', 'postgres' or 'mssql')")
+	flag.StringVar(&connectionString, "connstr", "", "adapter's connection string or file path if driver is 'file'")
+	flag.BoolVar(&dbSpecified, "dbspecified", false, "indicates whether the db is specified or not in the connstr")
 	flag.Parse()
 
 	if port < 1 || port > 65535 {
 		panic(fmt.Sprintf("invalid port number: %d", port))
 	}
 
+	if connectionString == "" {
+		panic("a connection string should be provided")
+	}
+
 	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
 	if err != nil {
 		log.Fatalf("failed to listen: %v", err)
 	}
 	s := grpc.NewServer()
-	pb.RegisterCasbinServer(s, server.NewServer())
+	pb.RegisterCasbinServer(s, server.NewServer(driverName, connectionString, dbSpecified))
 	// Register reflection service on gRPC server.
 	reflection.Register(s)
 	log.Println("Listening on", port)