ROX-20121: set gRPC max concurrent streams to 100

api/grpc/grpc.go

@@ -14,6 +14,7 @@ import (
 	grpcprometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
 	"github.com/grpc-ecosystem/grpc-gateway/runtime"
 	log "github.com/sirupsen/logrus"
+	"github.com/stackrox/scanner/pkg/env"
 	"github.com/stackrox/scanner/pkg/mtls"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
@@ -27,6 +28,14 @@ func init() {
 	grpcprometheus.EnableHandlingTimeHistogram()
 }
 
+func maxGrpcConcurrentStreams() uint32 {
+	if env.MaxGrpcConcurrentStreams.Int() <= 0 {
+		return env.DefaultMaxGrpcConcurrentStreams
+	}
+
+	return uint32(env.MaxGrpcConcurrentStreams.Int())
+}
+
 // NewAPI creates a new gRPC API instantiation
 func NewAPI(config Config) API {
 	return &apiImpl{
@@ -56,7 +65,11 @@ func (a *apiImpl) connectToLocalEndpoint() (*grpc.ClientConn, error) {
 }
 
 func (a *apiImpl) Start() {
-	grpcServer := grpc.NewServer(grpcmiddleware.WithUnaryServerChain(a.unaryInterceptors()...))
+	grpcServer := grpc.NewServer(
+		grpcmiddleware.WithUnaryServerChain(a.unaryInterceptors()...),
+		grpc.MaxConcurrentStreams(maxGrpcConcurrentStreams()),
+	)
+
 	for _, serv := range a.apiServices {
 		serv.RegisterServiceServer(grpcServer)
 	}

pkg/env/integersetting.go

@@ -0,0 +1,33 @@
+package env
+
+import (
+	"strconv"
+)
+
+// IntegerSetting represents an environment variable which should be parsed into an integer.
+type IntegerSetting interface {
+	Setting
+	Int() int
+}
+
+type integerSetting struct {
+	Setting
+	defaultValue int
+}
+
+// Int returns the int object represented by the environment variable.
+func (s *integerSetting) Int() int {
+	v, err := strconv.Atoi(s.Value())
+	if err != nil {
+		return s.defaultValue
+	}
+	return v
+}
+
+// RegisterIntegerSetting globally registers and returns a new integer setting.
+func RegisterIntegerSetting(envVar string, defaultValue int, opts ...SettingOption) IntegerSetting {
+	return &integerSetting{
+		Setting:      registerSetting(envVar, append(opts, WithDefault(strconv.Itoa(defaultValue)))...),
+		defaultValue: defaultValue,
+	}
+}

pkg/env/list.go

@@ -1,5 +1,10 @@
 package env
 
+const (
+	// DefaultMaxGrpcConcurrentStreams is the minimum value for concurrent streams recommended by the HTTP/2 spec
+	DefaultMaxGrpcConcurrentStreams = 100
+)
+
 var (
 	// LanguageVulns enables language vulnerabilities.
 	LanguageVulns = RegisterBooleanSetting("ROX_LANGUAGE_VULNS", true, AllowWithoutRox())
@@ -19,4 +24,7 @@ var (
 	// This is ignored if SkipPeerValidation is enabled.
 	// This variable was copied over from the stackrox repo.
 	OpenshiftAPI = RegisterBooleanSetting("ROX_OPENSHIFT_API", false)
+
+	// MaxGrpcConcurrentStreams configures the maximum number of HTTP/2 streams to use with gRPC
+	MaxGrpcConcurrentStreams = RegisterIntegerSetting("ROX_GRPC_MAX_CONCURRENT_STREAMS", DefaultMaxGrpcConcurrentStreams)
 )