Implement Query API discovery

cmd/thanos/query.go

@@ -675,6 +675,7 @@ func runQuery(
 			info.WithRulesInfoFunc(),
 			info.WithMetricMetadataInfoFunc(),
 			info.WithTargetsInfoFunc(),
+			info.WithQueryAPIInfoFunc(),
 		)
 
 		grpcAPI := apiv1.NewGRPCAPI(time.Now, queryableCreator, engineCreator, instantDefaultMaxSourceResolution)

pkg/info/info.go

@@ -25,6 +25,7 @@ type InfoServer struct {
 	getRulesInfo          func() *infopb.RulesInfo
 	getTargetsInfo        func() *infopb.TargetsInfo
 	getMetricMetadataInfo func() *infopb.MetricMetadataInfo
+	getQueryAPIInfo       func() *infopb.QueryAPIInfo
 }
 
 // NewInfoServer creates a new server instance for given component
@@ -42,6 +43,7 @@ func NewInfoServer(
 		getRulesInfo:          func() *infopb.RulesInfo { return nil },
 		getTargetsInfo:        func() *infopb.TargetsInfo { return nil },
 		getMetricMetadataInfo: func() *infopb.MetricMetadataInfo { return nil },
+		getQueryAPIInfo:       func() *infopb.QueryAPIInfo { return nil },
 	}
 
 	for _, o := range options {
@@ -144,6 +146,21 @@ func WithMetricMetadataInfoFunc(getMetricMetadataInfo ...func() *infopb.MetricMe
 	}
 }
 
+// WithQueryAPIInfoFunc determines the function that should be executed to obtain
+// the query information. If no function is provided, the default empty
+// query info is returned. Only the first function from the list is considered.
+func WithQueryAPIInfoFunc(queryInfo ...func() *infopb.QueryAPIInfo) ServerOptionFunc {
+	if len(queryInfo) == 0 {
+		return func(s *InfoServer) {
+			s.getQueryAPIInfo = func() *infopb.QueryAPIInfo { return &infopb.QueryAPIInfo{} }
+		}
+	}
+
+	return func(s *InfoServer) {
+		s.getQueryAPIInfo = queryInfo[0]
+	}
+}
+
 // RegisterInfoServer registers the info server.
 func RegisterInfoServer(infoSrv infopb.InfoServer) func(*grpc.Server) {
 	return func(s *grpc.Server) {
@@ -161,5 +178,6 @@ func (srv *InfoServer) Info(ctx context.Context, req *infopb.InfoRequest) (*info
 		Rules:          srv.getRulesInfo(),
 		Targets:        srv.getTargetsInfo(),
 		MetricMetadata: srv.getMetricMetadataInfo(),
+		Query:          srv.getQueryAPIInfo(),
 	}, nil
 }

pkg/info/infopb/rpc.proto

@@ -31,21 +31,24 @@ message InfoRequest {}
 message InfoResponse {
     repeated ZLabelSet label_sets      = 1 [(gogoproto.nullable) = false];
     string ComponentType               = 2;
-    
+
     // StoreInfo holds the metadata related to Store API if exposed by the component otherwise it will be null.
-    StoreInfo store                    = 3;    
+    StoreInfo store                    = 3;
 
     // RulesInfo holds the metadata related to Rules API if exposed by the component otherwise it will be null.
     RulesInfo rules                    = 4;
-    
+
     // MetricMetadataInfo holds the metadata related to Metadata API if exposed by the component otherwise it will be null.
     MetricMetadataInfo metric_metadata = 5;
-    
+
     // TargetsInfo holds the metadata related to Targets API if exposed by the component otherwise it will be null.
     TargetsInfo targets                = 6;
-    
+
     // ExemplarsInfo holds the metadata related to Exemplars API if exposed by the component otherwise it will be null.
     ExemplarsInfo exemplars            = 7;
+
+    // QueryAPIInfo holds the metadata related to Query API if exposed by the component, otherwise it will be null.
+    QueryAPIInfo query                 = 8;
 }
 
 // StoreInfo holds the metadata related to Store API exposed by the component.
@@ -70,4 +73,8 @@ message TargetsInfo {
 message ExemplarsInfo {
     int64 min_time = 1;
     int64 max_time = 2;
-}
+}
+
+// QueryInfo holds the metadata related to Query API exposed by the component.
+message QueryAPIInfo {
+}