cmd/contour: add EnableXRateLimitHeaders config file setting

cmd/contour/serve.go

@@ -350,10 +350,11 @@ func doServe(log logrus.FieldLogger, ctx *serveContext) error {
 		}
 
 		listenerConfig.RateLimitConfig = &xdscache_v3.RateLimitConfig{
-			ExtensionService: namespacedName,
-			Domain:           ctx.Config.RateLimitService.Domain,
-			Timeout:          responseTimeout,
-			FailOpen:         ctx.Config.RateLimitService.FailOpen,
+			ExtensionService:        namespacedName,
+			Domain:                  ctx.Config.RateLimitService.Domain,
+			Timeout:                 responseTimeout,
+			FailOpen:                ctx.Config.RateLimitService.FailOpen,
+			EnableXRateLimitHeaders: ctx.Config.RateLimitService.EnableXRateLimitHeaders,
 		}
 	}
 

examples/contour/01-contour-config.yaml

@@ -120,6 +120,12 @@ data:
     #   service fails to respond with a valid rate limit decision within
     #   the timeout defined on the extension service.
     #   failOpen: false
+    #   Defines whether to include the X-RateLimit headers X-RateLimit-Limit,
+    #   X-RateLimit-Remaining, and X-RateLimit-Reset (as defined by the IETF
+    #   Internet-Draft linked below), on responses to clients when the Rate
+    #   Limit Service is consulted for a request.
+    #   ref. https://tools.ietf.org/id/draft-polli-ratelimit-headers-03.html
+    #   enableXRateLimitHeaders: false
     #
     # Global Policy settings.
     # policy:

examples/render/contour.yaml

@@ -154,6 +154,12 @@ data:
     #   service fails to respond with a valid rate limit decision within
     #   the timeout defined on the extension service.
     #   failOpen: false
+    #   Defines whether to include the X-RateLimit headers X-RateLimit-Limit,
+    #   X-RateLimit-Remaining, and X-RateLimit-Reset (as defined by the IETF
+    #   Internet-Draft linked below), on responses to clients when the Rate
+    #   Limit Service is consulted for a request.
+    #   ref. https://tools.ietf.org/id/draft-polli-ratelimit-headers-03.html
+    #   enableXRateLimitHeaders: false
     #
     # Global Policy settings.
     # policy:

internal/envoy/v3/ratelimit.go

@@ -111,10 +111,11 @@ func GlobalRateLimits(descriptors []*dag.RateLimitDescriptor) []*envoy_route_v3.
 // GlobalRateLimitConfig stores configuration for
 // an HTTP global rate limiting filter.
 type GlobalRateLimitConfig struct {
-	ExtensionService types.NamespacedName
-	FailOpen         bool
-	Timeout          timeout.Setting
-	Domain           string
+	ExtensionService        types.NamespacedName
+	FailOpen                bool
+	Timeout                 timeout.Setting
+	Domain                  string
+	EnableXRateLimitHeaders bool
 }
 
 // GlobalRateLimitFilter returns a configured HTTP global rate limit filter,
@@ -141,7 +142,15 @@ func GlobalRateLimitFilter(config *GlobalRateLimitConfig) *http.HttpFilter {
 					},
 					TransportApiVersion: envoy_core_v3.ApiVersion_V3,
 				},
+				EnableXRatelimitHeaders: enableXRateLimitHeaders(config.EnableXRateLimitHeaders),
 			}),
 		},
 	}
 }
+
+func enableXRateLimitHeaders(enable bool) ratelimit_filter_v3.RateLimit_XRateLimitHeadersRFCVersion {
+	if enable {
+		return ratelimit_filter_v3.RateLimit_DRAFT_VERSION_03
+	}
+	return ratelimit_filter_v3.RateLimit_OFF
+}

internal/envoy/v3/ratelimit_test.go

@@ -180,35 +180,105 @@ func TestGlobalRateLimits(t *testing.T) {
 }
 
 func TestGlobalRateLimitFilter(t *testing.T) {
-	assert.Nil(t, GlobalRateLimitFilter(nil))
-
-	want := &http.HttpFilter{
-		Name: wellknown.HTTPRateLimit,
-		ConfigType: &http.HttpFilter_TypedConfig{
-			TypedConfig: protobuf.MustMarshalAny(&ratelimit_filter_v3.RateLimit{
-				Domain:          "domain",
-				Timeout:         protobuf.Duration(time.Second),
-				FailureModeDeny: false,
-				RateLimitService: &ratelimit_config_v3.RateLimitServiceConfig{
-					GrpcService: &envoy_core_v3.GrpcService{
-						TargetSpecifier: &envoy_core_v3.GrpcService_EnvoyGrpc_{
-							EnvoyGrpc: &envoy_core_v3.GrpcService_EnvoyGrpc{
-								ClusterName: "extension/projectcontour/ratelimit",
+	tests := map[string]struct {
+		cfg  *GlobalRateLimitConfig
+		want *http.HttpFilter
+	}{
+		"nil config produces nil filter": {
+			cfg:  nil,
+			want: nil,
+		},
+		"all fields configured correctly with FailOpen=false": {
+			cfg: &GlobalRateLimitConfig{
+				ExtensionService: k8s.NamespacedNameFrom("projectcontour/ratelimit"),
+				Timeout:          timeout.DurationSetting(7 * time.Second),
+				Domain:           "domain",
+				FailOpen:         false,
+			},
+			want: &http.HttpFilter{
+				Name: wellknown.HTTPRateLimit,
+				ConfigType: &http.HttpFilter_TypedConfig{
+					TypedConfig: protobuf.MustMarshalAny(&ratelimit_filter_v3.RateLimit{
+						Domain:          "domain",
+						Timeout:         protobuf.Duration(7 * time.Second),
+						FailureModeDeny: true,
+						RateLimitService: &ratelimit_config_v3.RateLimitServiceConfig{
+							GrpcService: &envoy_core_v3.GrpcService{
+								TargetSpecifier: &envoy_core_v3.GrpcService_EnvoyGrpc_{
+									EnvoyGrpc: &envoy_core_v3.GrpcService_EnvoyGrpc{
+										ClusterName: "extension/projectcontour/ratelimit",
+									},
+								},
 							},
+							TransportApiVersion: envoy_core_v3.ApiVersion_V3,
 						},
-					},
-					TransportApiVersion: envoy_core_v3.ApiVersion_V3,
+					}),
+				},
+			},
+		},
+		"all fields configured correctly with FailOpen=true": {
+			cfg: &GlobalRateLimitConfig{
+				ExtensionService: k8s.NamespacedNameFrom("projectcontour/ratelimit"),
+				Timeout:          timeout.DurationSetting(7 * time.Second),
+				Domain:           "domain",
+				FailOpen:         true,
+			},
+			want: &http.HttpFilter{
+				Name: wellknown.HTTPRateLimit,
+				ConfigType: &http.HttpFilter_TypedConfig{
+					TypedConfig: protobuf.MustMarshalAny(&ratelimit_filter_v3.RateLimit{
+						Domain:          "domain",
+						Timeout:         protobuf.Duration(7 * time.Second),
+						FailureModeDeny: false,
+						RateLimitService: &ratelimit_config_v3.RateLimitServiceConfig{
+							GrpcService: &envoy_core_v3.GrpcService{
+								TargetSpecifier: &envoy_core_v3.GrpcService_EnvoyGrpc_{
+									EnvoyGrpc: &envoy_core_v3.GrpcService_EnvoyGrpc{
+										ClusterName: "extension/projectcontour/ratelimit",
+									},
+								},
+							},
+							TransportApiVersion: envoy_core_v3.ApiVersion_V3,
+						},
+					}),
 				},
-			}),
+			},
+		},
+		"EnableXRateLimitHeaders=true is configured correctly": {
+			cfg: &GlobalRateLimitConfig{
+				ExtensionService:        k8s.NamespacedNameFrom("projectcontour/ratelimit"),
+				Timeout:                 timeout.DurationSetting(7 * time.Second),
+				Domain:                  "domain",
+				FailOpen:                true,
+				EnableXRateLimitHeaders: true,
+			},
+			want: &http.HttpFilter{
+				Name: wellknown.HTTPRateLimit,
+				ConfigType: &http.HttpFilter_TypedConfig{
+					TypedConfig: protobuf.MustMarshalAny(&ratelimit_filter_v3.RateLimit{
+						Domain:          "domain",
+						Timeout:         protobuf.Duration(7 * time.Second),
+						FailureModeDeny: false,
+						RateLimitService: &ratelimit_config_v3.RateLimitServiceConfig{
+							GrpcService: &envoy_core_v3.GrpcService{
+								TargetSpecifier: &envoy_core_v3.GrpcService_EnvoyGrpc_{
+									EnvoyGrpc: &envoy_core_v3.GrpcService_EnvoyGrpc{
+										ClusterName: "extension/projectcontour/ratelimit",
+									},
+								},
+							},
+							TransportApiVersion: envoy_core_v3.ApiVersion_V3,
+						},
+						EnableXRatelimitHeaders: ratelimit_filter_v3.RateLimit_DRAFT_VERSION_03,
+					}),
+				},
+			},
 		},
 	}
 
-	cfg := &GlobalRateLimitConfig{
-		ExtensionService: k8s.NamespacedNameFrom("projectcontour/ratelimit"),
-		FailOpen:         true,
-		Timeout:          timeout.DurationSetting(time.Second),
-		Domain:           "domain",
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			assert.Equal(t, tc.want, GlobalRateLimitFilter(tc.cfg))
+		})
 	}
-
-	assert.Equal(t, want, GlobalRateLimitFilter(cfg))
 }

internal/xdscache/v3/listener.go

@@ -141,10 +141,11 @@ type ListenerConfig struct {
 }
 
 type RateLimitConfig struct {
-	ExtensionService types.NamespacedName
-	Domain           string
-	Timeout          timeout.Setting
-	FailOpen         bool
+	ExtensionService        types.NamespacedName
+	Domain                  string
+	Timeout                 timeout.Setting
+	FailOpen                bool
+	EnableXRateLimitHeaders bool
 }
 
 // httpAddress returns the port for the HTTP (non TLS)
@@ -406,10 +407,11 @@ func envoyGlobalRateLimitConfig(config *RateLimitConfig) *envoy_v3.GlobalRateLim
 	}
 
 	return &envoy_v3.GlobalRateLimitConfig{
-		ExtensionService: config.ExtensionService,
-		FailOpen:         config.FailOpen,
-		Timeout:          config.Timeout,
-		Domain:           config.Domain,
+		ExtensionService:        config.ExtensionService,
+		FailOpen:                config.FailOpen,
+		Timeout:                 config.Timeout,
+		Domain:                  config.Domain,
+		EnableXRateLimitHeaders: config.EnableXRateLimitHeaders,
 	}
 }