[remote-storage][v2] Add proto definition for GetServices and `GetO…

…perations` rpc (#6736)

## Which problem is this PR solving?
- Resolves #6629

## Description of the changes
- This PR creates a protobuf definition in traces_storage.proto for the
`GetServices` and `GetOperations` RPCs.

## How was this change tested?
- CI

## Checklist
- [x] I have read
https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
- [x] I have signed all commits
- [x] I have added unit tests for the new functionality
- [x] I have run lint and test steps successfully
  - for `jaeger`: `make lint test`
  - for `jaeger-ui`: `npm run lint` and `npm run test`

---------

Signed-off-by: Mahad Zaryab <[email protected]>

internal/storage/v2/grpc/trace_storage.proto

@@ -10,40 +10,77 @@ option go_package = "storage";
 
 // GetTraceParams represents the query for a single trace from the storage backend.
 message GetTraceParams {
-    // trace_id is a 16 byte array containing the unique identifier for the trace to query. 
-    bytes trace_id = 1;
-
-    // start_time is the start of the time interval to search for the trace_id.
-    //
-    // This field is optional.
-    google.protobuf.Timestamp start_time = 2 [
-      (gogoproto.stdtime) = true
-    ];
-
-    // end_time is the end of the time interval to search for the trace_id.
-    //
-    // This field is optional.
-    google.protobuf.Timestamp end_time = 3 [
-      (gogoproto.stdtime) = true
-    ];
+  // trace_id is a 16 byte array containing the unique identifier for the trace to query.
+  bytes trace_id = 1;
+
+  // start_time is the start of the time interval to search for the trace_id.
+  //
+  // This field is optional.
+  google.protobuf.Timestamp start_time = 2 [(gogoproto.stdtime) = true];
+
+  // end_time is the end of the time interval to search for the trace_id.
+  //
+  // This field is optional.
+  google.protobuf.Timestamp end_time = 3 [(gogoproto.stdtime) = true];
 }
 
 // GetTracesRequest represents a request to retrieve multiple traces.
 message GetTracesRequest {
   repeated GetTraceParams query = 1;
 }
 
+// GetServicesRequest represents a request to get service names.
+message GetServicesRequest {}
+
+// GetServicesResponse represents the response for GetServicesRequest.
+message GetServicesResponse {
+  repeated string services = 1;
+}
+
+// GetOperationsRequest represents a request to get operation names.
+message GetOperationsRequest {
+  // service is the name of the service for which to get operation names.
+  //
+  // This field is required.
+  string service = 1;
+
+  // span_kind is the type of span which is used to distinguish between
+  // spans generated in a particular context.
+  //
+  // This field is optional.
+  opentelemetry.proto.trace.v1.Span.SpanKind span_kind = 2;
+}
+
+// Operation contains information about an operation for a given service.
+message Operation {
+  string name = 1;
+  opentelemetry.proto.trace.v1.Span.SpanKind span_kind = 2;
+}
+
+// GetOperationsResponse represents the response for GetOperationsRequest.
+message GetOperationsResponse {
+  repeated Operation operations = 1;
+}
+
 service TraceReader {
-	// GetTraces returns a stream that retrieves all traces with given IDs.
-	//
-	// Chunking requirements:
-	// - A single TracesData chunk MUST NOT contain spans from multiple traces.
-	// - Large traces MAY be split across multiple, *consecutive* TracesData chunks.
-	// - Each returned TracesData object MUST NOT be empty.
-	//
-	// Edge cases:
-	// - If no spans are found for any given trace ID, the ID is ignored.
-	// - If none of the trace IDs are found in the storage, an empty response is returned.
-	// - If an error is encountered, the stream returns the error and stops.
-    rpc GetTraces(GetTracesRequest) returns (stream opentelemetry.proto.trace.v1.TracesData) {}
-}
+  // GetTraces returns a stream that retrieves all traces with given IDs.
+  //
+  // Chunking requirements:
+  // - A single TracesData chunk MUST NOT contain spans from multiple traces.
+  // - Large traces MAY be split across multiple, *consecutive* TracesData chunks.
+  // - Each returned TracesData object MUST NOT be empty.
+  //
+  // Edge cases:
+  // - If no spans are found for any given trace ID, the ID is ignored.
+  // - If none of the trace IDs are found in the storage, an empty response is returned.
+  // - If an error is encountered, the stream returns the error and stops.
+  rpc GetTraces(GetTracesRequest) returns (stream opentelemetry.proto.trace.v1.TracesData) {}
+
+  // GetServices returns all service names known to the backend from traces
+  // within its retention period.
+  rpc GetServices(GetServicesRequest) returns (GetServicesResponse) {}
+
+  // GetOperations returns all operation names for a given service
+  // known to the backend from traces within its retention period.
+  rpc GetOperations(GetOperationsRequest) returns (GetOperationsResponse) {}
+}