feat(gw): added connection with retry

internal/gw/grpc_client/auth_client.go

@@ -15,7 +15,7 @@ type AuthClient struct {
 }
 
 func NewAuthClient(ctx context.Context, address string, factory *ClientFactory) (*AuthClient, error) {
-	conn, err := factory.GetConnection(ctx, address)
+	conn, err := factory.GetConnectionWithRetry(ctx, address)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create auth client: %w", err)
 	}

internal/gw/grpc_client/client.go

@@ -6,7 +6,9 @@ import (
 	"time"
 
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/status"
 )
 
 type ClientFactory struct {
@@ -19,6 +21,11 @@ func NewClientFactory() *ClientFactory {
 	}
 }
 
+const (
+	maxRetries = 3
+	retryDelay = 500 * time.Millisecond
+)
+
 func (f *ClientFactory) GetConnection(ctx context.Context, address string) (*grpc.ClientConn, error) {
 	if conn, ok := f.connections[address]; ok {
 		return conn, nil
@@ -39,6 +46,28 @@ func (f *ClientFactory) GetConnection(ctx context.Context, address string) (*grp
 	return conn, nil
 }
 
+func (f *ClientFactory) GetConnectionWithRetry(ctx context.Context, address string) (*grpc.ClientConn, error) {
+	var conn *grpc.ClientConn
+	var err error
+
+	for i := 0; i < maxRetries; i++ {
+		conn, err = f.GetConnection(ctx, address)
+		if err == nil {
+			return conn, nil
+		}
+
+		st, ok := status.FromError(err)
+		if ok && (st.Code() == codes.Unavailable || st.Code() == codes.ResourceExhausted) {
+			time.Sleep(retryDelay)
+			continue
+		}
+
+		break
+	}
+
+	return nil, fmt.Errorf("failed to connect to %s after %d retries: %w", address, maxRetries, err)
+}
+
 func (f *ClientFactory) Close() error {
 	for addr, conn := range f.connections {
 		if err := conn.Close(); err != nil {

internal/gw/grpc_client/competition_client.go

@@ -15,7 +15,7 @@ type CompetitionClient struct {
 }
 
 func NewCompetitionClient(ctx context.Context, address string, factory *ClientFactory) (*CompetitionClient, error) {
-	conn, err := factory.GetConnection(ctx, address)
+	conn, err := factory.GetConnectionWithRetry(ctx, address)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create competition client: %w", err)
 	}