Use X-Forwarded-* headers to construct endpoint URL (#2051)

Fix #2012

Author: eleftherias

cmd/thv-operator/api/v1alpha1/mcpserver_types.go

@@ -119,6 +119,13 @@ type MCPServerSpec struct {
 	// Telemetry defines observability configuration for the MCP server
 	// +optional
 	Telemetry *TelemetryConfig `json:"telemetry,omitempty"`
+
+	// TrustProxyHeaders indicates whether to trust X-Forwarded-* headers from reverse proxies
+	// When enabled, the proxy will use X-Forwarded-Proto, X-Forwarded-Host, X-Forwarded-Port,
+	// and X-Forwarded-Prefix headers to construct endpoint URLs
+	// +kubebuilder:default=false
+	// +optional
+	TrustProxyHeaders bool `json:"trustProxyHeaders,omitempty"`
 }
 
 // ResourceOverrides defines overrides for annotations and labels on created resources

cmd/thv-operator/controllers/mcpserver_controller.go

@@ -807,6 +807,10 @@ func (r *MCPServerReconciler) deploymentForMCPServer(ctx context.Context, m *mcp
 		if m.Spec.ProxyMode != "" {
 			args = append(args, fmt.Sprintf("--proxy-mode=%s", m.Spec.ProxyMode))
 		}
+		// Add trust proxy headers flag if enabled
+		if m.Spec.TrustProxyHeaders {
+			args = append(args, "--trust-proxy-headers")
+		}
 	}
 
 	// Add pod template patch and permission profile only if not using ConfigMap

cmd/thv-operator/controllers/mcpserver_runconfig.go

@@ -263,6 +263,7 @@ func (r *MCPServerReconciler) createRunConfigFromMCPServer(m *mcpv1alpha1.MCPSer
 		runner.WithTransportAndPorts(m.Spec.Transport, port, int(m.Spec.TargetPort)),
 		runner.WithProxyMode(transporttypes.ProxyMode(proxyMode)),
 		runner.WithHost(proxyHost),
+		runner.WithTrustProxyHeaders(m.Spec.TrustProxyHeaders),
 		runner.WithToolsFilter(toolsFilter),
 		runner.WithEnvVars(envVars),
 		runner.WithVolumes(volumes),

cmd/thv-proxyrunner/app/execution.go

@@ -43,6 +43,7 @@ func runWithFlagsBasedConfig(
 		runner.WithHost(validatedHost),
 		runner.WithTargetHost(transport.LocalhostIPv4),
 		runner.WithProxyMode(types.ProxyMode(runFlags.runProxyMode)),
+		runner.WithTrustProxyHeaders(runFlags.runTrustProxyHeaders),
 		runner.WithVolumes(runFlags.runVolumes),
 		runner.WithSecrets(runFlags.runSecrets),
 		runner.WithAuthzConfigPath(runFlags.runAuthzConfig),

cmd/thv-proxyrunner/app/run.go

@@ -87,6 +87,9 @@ type proxyRunFlags struct {
 	// Network isolation flag
 	runIsolateNetwork bool
 
+	// Trust proxy headers flag
+	runTrustProxyHeaders bool
+
 	// Tools filter
 	runToolsFilter []string
 
@@ -217,6 +220,8 @@ func addRunFlags(runCmd *cobra.Command, runFlags *proxyRunFlags) {
 		"Enable Prometheus-style /metrics endpoint on the main transport port")
 	runCmd.Flags().BoolVar(&runFlags.runIsolateNetwork, "isolate-network", false,
 		"Isolate the container network from the host (default: false)")
+	runCmd.Flags().BoolVar(&runFlags.runTrustProxyHeaders, "trust-proxy-headers", false,
+		"Trust X-Forwarded-* headers from reverse proxies (X-Forwarded-Proto, X-Forwarded-Host, X-Forwarded-Port, X-Forwarded-Prefix)")
 	runCmd.Flags().StringArrayVar(
 		&runFlags.runToolsFilter,
 		"tools",

cmd/thv/app/run_flags.go

@@ -82,6 +82,9 @@ type RunFlags struct {
 	// Network isolation
 	IsolateNetwork bool
 
+	// Proxy headers
+	TrustProxyHeaders bool
+
 	// Labels
 	Labels []string
 
@@ -195,6 +198,8 @@ func AddRunFlags(cmd *cobra.Command, config *RunFlags) {
 
 	cmd.Flags().BoolVar(&config.IsolateNetwork, "isolate-network", false,
 		"Isolate the container network from the host (default: false)")
+	cmd.Flags().BoolVar(&config.TrustProxyHeaders, "trust-proxy-headers", false,
+		"Trust X-Forwarded-* headers from reverse proxies (X-Forwarded-Proto, X-Forwarded-Host, X-Forwarded-Port, X-Forwarded-Prefix)")
 	cmd.Flags().StringArrayVarP(&config.Labels, "label", "l", []string{}, "Set labels on the container (format: key=value)")
 	cmd.Flags().BoolVarP(&config.Foreground, "foreground", "f", false, "Run in foreground mode (block until container exits)")
 	cmd.Flags().StringArrayVar(
@@ -428,6 +433,7 @@ func buildRunnerConfig(
 		runner.WithAuditConfigPath(runFlags.AuditConfig),
 		runner.WithPermissionProfileNameOrPath(runFlags.PermissionProfile),
 		runner.WithNetworkIsolation(runFlags.IsolateNetwork),
+		runner.WithTrustProxyHeaders(runFlags.TrustProxyHeaders),
 		runner.WithK8sPodPatch(runFlags.K8sPodPatch),
 		runner.WithProxyMode(types.ProxyMode(runFlags.ProxyMode)),
 		runner.WithTransportAndPorts(transportType, runFlags.ProxyPort, runFlags.TargetPort),

deploy/charts/operator-crds/Chart.yaml

@@ -2,5 +2,5 @@ apiVersion: v2
 name: toolhive-operator-crds
 description: A Helm chart for installing the ToolHive Operator CRDs into Kubernetes.
 type: application
-version: 0.0.31
+version: 0.0.32
 appVersion: "0.0.1"

deploy/charts/operator-crds/README.md

@@ -1,7 +1,7 @@
 
 # ToolHive Operator CRDs Helm Chart
 
-![Version: 0.0.31](https://img.shields.io/badge/Version-0.0.31-informational?style=flat-square)
+![Version: 0.0.32](https://img.shields.io/badge/Version-0.0.32-informational?style=flat-square)
 ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square)
 
 A Helm chart for installing the ToolHive Operator CRDs into Kubernetes.

deploy/charts/operator-crds/crds/toolhive.stacklok.dev_mcpservers.yaml

@@ -8942,6 +8942,13 @@ spec:
                 - streamable-http
                 - sse
                 type: string
+              trustProxyHeaders:
+                default: false
+                description: |-
+                  TrustProxyHeaders indicates whether to trust X-Forwarded-* headers from reverse proxies
+                  When enabled, the proxy will use X-Forwarded-Proto, X-Forwarded-Host, X-Forwarded-Port,
+                  and X-Forwarded-Prefix headers to construct endpoint URLs
+                type: boolean
               volumes:
                 description: Volumes are volumes to mount in the MCP server container
                 items: