chore: enable gRPC auto retries for transient Unavailable failures up to ~8s

pkg/client/connector/common.go

@@ -0,0 +1,30 @@
+package connector
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// defaultServiceConfig defines the default gRPC service configuration including retry policy for transient failures.
+var defaultServiceConfig = mustMarshalJSON(map[string]any{
+	"methodConfig": []map[string]any{
+		{
+			"name": []map[string]string{{"service": ""}},
+			"retryPolicy": map[string]any{
+				"maxAttempts":          5, // 5 is the maximum allowed by gRPC
+				"initialBackoff":       "0.5s",
+				"maxBackoff":           "5s",
+				"backoffMultiplier":    2,
+				"retryableStatusCodes": []string{"UNAVAILABLE"},
+			},
+		},
+	},
+})
+
+func mustMarshalJSON(v any) string {
+	b, err := json.Marshal(v)
+	if err != nil {
+		panic(fmt.Sprintf("failed to marshal service config: %v", err))
+	}
+	return string(b)
+}