refactor(metric): adds filter function to collector init method (#2695)

internal/daemon/metric/initialize_metrics.go

@@ -33,7 +33,10 @@ var (
 
 /* The following methods are used to initialize Prometheus histogram vectors for gRPC connections. */
 
-func rangeProtoFiles(m map[string][]string, fd protoreflect.FileDescriptor) bool {
+// rangeProtoFiles returns true while there are services with associated methods in the proto package.
+// It relies on RangeFilesByPackage to range through the package, and it adds them into map m.
+// Services and methods for which filter() returns true are not added into the map.
+func rangeProtoFiles(m map[string][]string, fd protoreflect.FileDescriptor, filter func(string, string) bool) bool {
 	if fd.Services().Len() == 0 {
 		return true
 	}
@@ -44,11 +47,18 @@ func rangeProtoFiles(m map[string][]string, fd protoreflect.FileDescriptor) bool
 			continue
 		}
 
+		serviceName := string(s.FullName())
 		methods := []string{}
 		for j := 0; j < s.Methods().Len(); j++ {
-			methods = append(methods, string(s.Methods().Get(j).Name()))
+			methodName := string(s.Methods().Get(j).Name())
+			if filter(serviceName, methodName) {
+				continue
+			}
+			methods = append(methods, methodName)
+		}
+		if len(methods) > 0 {
+			m[serviceName] = methods
 		}
-		m[string(s.FullName())] = methods
 	}
 
 	return true
@@ -56,27 +66,32 @@ func rangeProtoFiles(m map[string][]string, fd protoreflect.FileDescriptor) bool
 
 // appendServicesAndMethods ranges through all registered files in a specified proto package
 // and appends service and method names to the provided map m.
-// This method is exported for testing purposes.
-func appendServicesAndMethods(m map[string][]string, pkg protoreflect.FileDescriptor) {
+func appendServicesAndMethods(m map[string][]string, pkg protoreflect.FileDescriptor, filter func(string, string) bool) {
 	protoregistry.GlobalFiles.RangeFilesByPackage(
 		pkg.Package(),
-		func(fd protoreflect.FileDescriptor) bool { return rangeProtoFiles(m, fd) },
+		func(fd protoreflect.FileDescriptor) bool { return rangeProtoFiles(m, fd, filter) },
 	)
 }
 
 // InitializeGrpcCollectorsFromPackage registers and zeroes a Prometheus
 // histogram, populating all service and method labels by ranging through
 // the package containing the provided FileDescriptor.
+// The filter function takes in a service name and method name and skips adding them as labels
+// upon returning true.
 // Note: inputting a protoreflect.FileDescriptor will populate all services and methods
 // found in its package, not just methods associated with that specific FileDescriptor.
-func InitializeGrpcCollectorsFromPackage(r prometheus.Registerer, v prometheus.ObserverVec, pkg protoreflect.FileDescriptor, codes []codes.Code) {
+func InitializeGrpcCollectorsFromPackage(r prometheus.Registerer, v prometheus.ObserverVec,
+	pkgs []protoreflect.FileDescriptor, codes []codes.Code, filter func(string, string) bool,
+) {
 	if r == nil {
 		return
 	}
 	r.MustRegister(v)
 
 	serviceNamesToMethodNames := make(map[string][]string, 0)
-	appendServicesAndMethods(serviceNamesToMethodNames, pkg)
+	for _, p := range pkgs {
+		appendServicesAndMethods(serviceNamesToMethodNames, p, filter)
+	}
 
 	for serviceName, serviceMethods := range serviceNamesToMethodNames {
 		for _, sm := range serviceMethods {

internal/daemon/metric/initialize_metrics_test.go

@@ -16,17 +16,35 @@ func Test_AppendServicesAndMethods(t *testing.T) {
 	cases := []struct {
 		name     string
 		pkg      protoreflect.FileDescriptor
+		filter   func(string, string) bool
 		expected map[string][]string
 	}{
 		{
 			name:     "basic",
 			pkg:      protooptions.File_testing_options_v1_service_proto,
+			filter:   func(string, string) bool { return false },
+			expected: map[string][]string{"testing.options.v1.TestService": {"TestMethod"}},
+		},
+		{
+			name: "filter-out",
+			pkg:  protooptions.File_testing_options_v1_service_proto,
+			filter: func(_ string, m string) bool {
+				return m == "TestMethod"
+			},
+			expected: map[string][]string{},
+		},
+		{
+			name: "filter-allow",
+			pkg:  protooptions.File_testing_options_v1_service_proto,
+			filter: func(_ string, m string) bool {
+				return m != "TestMethod"
+			},
 			expected: map[string][]string{"testing.options.v1.TestService": {"TestMethod"}},
 		},
 	}
 	for _, tc := range cases {
 		m := make(map[string][]string, 0)
-		appendServicesAndMethods(m, tc.pkg)
+		appendServicesAndMethods(m, tc.pkg, tc.filter)
 		assert.Equal(t, tc.expected, m)
 	}
 }

internal/daemon/worker/internal/metric/cluster_client.go

@@ -6,16 +6,25 @@ import (
 
 	"github.com/hashicorp/boundary/globals"
 	"github.com/hashicorp/boundary/internal/daemon/metric"
-	"github.com/hashicorp/boundary/internal/gen/controller/servers/services"
+	cservices "github.com/hashicorp/boundary/internal/gen/controller/servers/services"
 	"github.com/prometheus/client_golang/prometheus"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/protobuf/reflect/protoreflect"
 )
 
 const (
 	clusterClientSubsystem = "cluster_client"
 )
 
+// grpcCollectorFilter is currently used to filter the services and methods of the
+// controller.servers.services package upon running InitializeClusterClientCollectors.
+var grpcCollectorFilter = noopFilter
+
+func noopFilter(serviceName string, methodName string) bool {
+	return false
+}
+
 // grpcRequestLatency collects measurements of how long a gRPC
 // request between a cluster and its clients takes.
 var grpcRequestLatency prometheus.ObserverVec = prometheus.NewHistogramVec(
@@ -37,8 +46,7 @@ type requestRecorder struct {
 	start time.Time
 }
 
-// NewRequestRecorder creates a requestRecorder struct which is used to measure gRPC client request latencies.
-// For testing purposes, this method is exported.
+// newRequestRecorder creates a requestRecorder struct which is used to measure gRPC client request latencies.
 func newRequestRecorder(fullMethodName string, reqLatency prometheus.ObserverVec) requestRecorder {
 	service, method := metric.SplitMethodName(fullMethodName)
 	r := requestRecorder{
@@ -82,5 +90,8 @@ func InstrumentClusterClient() grpc.UnaryClientInterceptor {
 // prometheus register and initializes them to 0 for all possible label
 // combinations.
 func InitializeClusterClientCollectors(r prometheus.Registerer) {
-	metric.InitializeGrpcCollectorsFromPackage(r, grpcRequestLatency, services.File_controller_servers_services_v1_session_service_proto, expectedGrpcClientCodes)
+	metric.InitializeGrpcCollectorsFromPackage(r, grpcRequestLatency,
+		[]protoreflect.FileDescriptor{
+			cservices.File_controller_servers_services_v1_session_service_proto,
+		}, expectedGrpcClientCodes, grpcCollectorFilter)
 }