feat: added API gateway

internal/gw/grpc_client/client.go

@@ -0,0 +1,49 @@
+package grpc_client
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+type ClientFactory struct {
+	connections map[string]*grpc.ClientConn
+}
+
+func NewClientFactory() *ClientFactory {
+	return &ClientFactory{
+		connections: make(map[string]*grpc.ClientConn),
+	}
+}
+
+func (f *ClientFactory) GetConnection(ctx context.Context, address string) (*grpc.ClientConn, error) {
+	if conn, ok := f.connections[address]; ok {
+		return conn, nil
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+
+	conn, err := grpc.DialContext(ctx, address,
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithBlock(),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect to %s: %w", address, err)
+	}
+
+	f.connections[address] = conn
+	return conn, nil
+}
+
+func (f *ClientFactory) Close() error {
+	for addr, conn := range f.connections {
+		if err := conn.Close(); err != nil {
+			return fmt.Errorf("failed to close connection to %s: %w", addr, err)
+		}
+	}
+	return nil
+}