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Merged
nacx merged 8 commits into from
Feb 8, 2026
Merged

mcp: query param APIKey #1800

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f312d5c
mcp: query param APIKey
mathetake Jan 21, 2026
ef669d0
simplify
mathetake Jan 26, 2026
3f81e9d
drift
mathetake Jan 27, 2026
42d8a06
simplify
mathetake Jan 27, 2026
b0ddbbb
e2e test
mathetake Jan 27, 2026
3f4f949
CEL done
mathetake Jan 27, 2026
24a8827
Merge branch 'main' into queryparammcp
nacx Feb 2, 2026
0c84721
Merge branch 'main' into queryparammcp
mathetake Feb 8, 2026
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15 changes: 15 additions & 0 deletions api/v1alpha1/mcp_route.go
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Original file line number Diff line number Diff line change
Expand Up @@ -152,8 +152,10 @@ type MCPBackendSecurityPolicy struct {
}

// MCPBackendAPIKey defines the configuration for the API Key Authentication to a backend.
// When both `header` and `queryParam` are unspecified, the API key will be injected into the "Authorization" header by default.
//
// +kubebuilder:validation:XValidation:rule="(has(self.secretRef) && !has(self.inline)) || (!has(self.secretRef) && has(self.inline))", message="exactly one of secretRef or inline must be set"
// +kubebuilder:validation:XValidation:rule="!(has(self.header) && has(self.queryParam))", message="only one of header or queryParam can be set"
type MCPBackendAPIKey struct {
// secretRef is the Kubernetes secret which contains the API keys.
// The key of the secret should be "apiKey".
Expand All @@ -170,10 +172,23 @@ type MCPBackendAPIKey struct {
// When the header is "Authorization", the injected header value will be
// prefixed with "Bearer ".
//
// Either one of Header or QueryParam can be specified to inject the API key.
//
// +kubebuilder:validation:Optional
// +kubebuilder:validation:MinLength=1
// +optional
Header *string `json:"header,omitempty"`

// QueryParam is the HTTP query parameter to inject the API key into.
// For example, if QueryParam is set to "api_key", and the API key is "mysecretkey", the request URL will be modified to include
// "?api_key=mysecretkey".
//
// Either one of Header or QueryParam can be specified to inject the API key.
//
// +kubebuilder:validation:Optional
// +kubebuilder:validation:MinLength=1
// +optional
QueryParam *string `json:"queryParam,omitempty"`
}

// MCPRouteSecurityPolicy defines the security policy for a MCPRoute.
Expand Down
5 changes: 5 additions & 0 deletions api/v1alpha1/zz_generated.deepcopy.go
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1 change: 0 additions & 1 deletion internal/controller/gateway.go
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Original file line number Diff line number Diff line change
Expand Up @@ -495,7 +495,6 @@ func mcpConfig(mcpRoutes []aigv1a1.MCPRoute) (_ *filterapi.MCPConfig, hasEffecti
mcpBackend := filterapi.MCPBackend{
// MCPRoute doesn't support cross-namespace backend reference so just use the name.
Name: filterapi.MCPBackendName(b.Name),
Path: ptr.Deref(b.Path, "/mcp"),
}
if b.ToolSelector != nil {
mcpBackend.ToolSelector = &filterapi.MCPToolSelector{
Expand Down
154 changes: 69 additions & 85 deletions internal/controller/mcp_route.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,14 +6,12 @@
package controller

import (
"cmp"
"context"
"fmt"
"strings"

egv1a1 "github.com/envoyproxy/gateway/api/v1alpha1"
"github.com/go-logr/logr"
corev1 "k8s.io/api/core/v1"
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/client-go/kubernetes"
Expand Down Expand Up @@ -499,26 +497,76 @@ func mcpBackendRefFilterName(mcpRoute *aigv1a1.MCPRoute, backendName gwapiv1.Obj
// which is set by the MCP proxy based on its routing logic.
// This route rule will eventually be moved to the backend listener in the extension server.
func (c *MCPRouteController) mcpBackendRefToHTTPRouteRule(ctx context.Context, mcpRoute *aigv1a1.MCPRoute, ref *aigv1a1.MCPRouteBackendRef) (gwapiv1.HTTPRouteRule, error) {
var apiKey *aigv1a1.MCPBackendAPIKey
if ref.SecurityPolicy != nil && ref.SecurityPolicy.APIKey != nil {
apiKey = ref.SecurityPolicy.APIKey
}

// Ensure the HTTPRouteFilter for this backend with its optional security configuration.
filterName := mcpBackendRefFilterName(mcpRoute, ref.Name)
err := c.ensureMCPBackendRefHTTPFilter(ctx, filterName, apiKey, mcpRoute)
egFilterName := mcpBackendRefFilterName(mcpRoute, ref.Name)
err := c.ensureMCPBackendRefHTTPFilter(ctx, egFilterName, mcpRoute)
if err != nil {
return gwapiv1.HTTPRouteRule{}, fmt.Errorf("failed to ensure MCP backend API key HTTP filter: %w", err)
}
filters := []gwapiv1.HTTPRouteFilter{
{
Type: gwapiv1.HTTPRouteFilterExtensionRef,
ExtensionRef: &gwapiv1.LocalObjectReference{
Group: "gateway.envoyproxy.io",
Kind: "HTTPRouteFilter",
Name: gwapiv1.ObjectName(egFilterName),
},
},
}

fullPathPtr := ptr.Deref(ref.Path, defaultMCPPath)

filters := []gwapiv1.HTTPRouteFilter{{
Type: gwapiv1.HTTPRouteFilterExtensionRef,
ExtensionRef: &gwapiv1.LocalObjectReference{
Group: "gateway.envoyproxy.io",
Kind: "HTTPRouteFilter",
Name: gwapiv1.ObjectName(filterName),
// Add credential injection if apiKey is specified.
if ref.SecurityPolicy != nil && ref.SecurityPolicy.APIKey != nil {
apiKey := ref.SecurityPolicy.APIKey

apiKeyLiteral, err := c.readAPIKey(ctx, mcpRoute.Namespace, apiKey)
if err != nil {
return gwapiv1.HTTPRouteRule{}, fmt.Errorf("failed to read API key for backend %s: %w", ref.Name, err)
}
switch {
case apiKey.QueryParam != nil:
fullPathPtr = fmt.Sprintf("%s?%s=%s", fullPathPtr, *apiKey.QueryParam, apiKeyLiteral)
case apiKey.Header != nil:
header := *apiKey.Header
if header == "Authorization" {
apiKeyLiteral = "Bearer " + apiKeyLiteral
}
filters = append(filters,
gwapiv1.HTTPRouteFilter{
Type: gwapiv1.HTTPRouteFilterRequestHeaderModifier,
RequestHeaderModifier: &gwapiv1.HTTPHeaderFilter{
Set: []gwapiv1.HTTPHeader{
{Name: gwapiv1.HTTPHeaderName(header), Value: apiKeyLiteral},
},
},
},
)
default:
filters = append(filters,
gwapiv1.HTTPRouteFilter{
Type: gwapiv1.HTTPRouteFilterRequestHeaderModifier,
RequestHeaderModifier: &gwapiv1.HTTPHeaderFilter{
Set: []gwapiv1.HTTPHeader{
{Name: "Authorization", Value: "Bearer " + apiKeyLiteral},
},
},
},
)
}
}

filters = append(filters,
gwapiv1.HTTPRouteFilter{
Type: gwapiv1.HTTPRouteFilterURLRewrite,
URLRewrite: &gwapiv1.HTTPURLRewriteFilter{
Path: &gwapiv1.HTTPPathModifier{
Type: gwapiv1.FullPathHTTPPathModifier,
ReplaceFullPath: ptr.To(fullPathPtr),
},
},
},
}}
)
return gwapiv1.HTTPRouteRule{
Matches: []gwapiv1.HTTPRouteMatch{
{
Expand Down Expand Up @@ -555,7 +603,7 @@ func mcpRouteHeaderValue(mcpRoute *aigv1a1.MCPRoute) string {
}

// ensureMCPBackendRefHTTPFilter ensures that an HTTPRouteFilter exists for the given backend reference in the MCPRoute.
func (c *MCPRouteController) ensureMCPBackendRefHTTPFilter(ctx context.Context, filterName string, apiKey *aigv1a1.MCPBackendAPIKey, mcpRoute *aigv1a1.MCPRoute) error {
func (c *MCPRouteController) ensureMCPBackendRefHTTPFilter(ctx context.Context, filterName string, mcpRoute *aigv1a1.MCPRoute) error {
// Rewrite the hostname to the backend service name.
// This allows Envoy to route to public MCP services with SNI matching the service name.
// This could be a standalone filter and moved to the main mcp gateway route logic.
Expand All @@ -575,25 +623,6 @@ func (c *MCPRouteController) ensureMCPBackendRefHTTPFilter(ctx context.Context,
if err := ctrlutil.SetControllerReference(mcpRoute, filter, c.client.Scheme()); err != nil {
return fmt.Errorf("failed to set controller reference for HTTPRouteFilter: %w", err)
}

// add credential injection if apiKey is specified.
if apiKey != nil {
secretName := fmt.Sprintf("%s-credential", filterName)
if secretErr := c.ensureCredentialSecret(ctx, mcpRoute.Namespace, secretName, apiKey, mcpRoute); secretErr != nil {
return fmt.Errorf("failed to ensure credential secret: %w", secretErr)
}
header := cmp.Or(ptr.Deref(apiKey.Header, ""), "Authorization")
filter.Spec.CredentialInjection = &egv1a1.HTTPCredentialInjectionFilter{
Header: ptr.To(header),
Overwrite: ptr.To(true),
Credential: egv1a1.InjectedCredential{
ValueRef: gwapiv1.SecretObjectReference{
Name: gwapiv1.ObjectName(secretName),
},
},
}
}

// Create or Update the HTTPRouteFilter.
var existingFilter egv1a1.HTTPRouteFilter
err := c.client.Get(ctx, client.ObjectKey{Name: filterName, Namespace: mcpRoute.Namespace}, &existingFilter)
Expand All @@ -617,64 +646,19 @@ func (c *MCPRouteController) ensureMCPBackendRefHTTPFilter(ctx context.Context,
return nil
}

func (c *MCPRouteController) ensureCredentialSecret(ctx context.Context, namespace, secretName string, apiKey *aigv1a1.MCPBackendAPIKey, mcpRoute *aigv1a1.MCPRoute) error {
var credentialValue string
func (c *MCPRouteController) readAPIKey(ctx context.Context, namespace string, apiKey *aigv1a1.MCPBackendAPIKey) (string, error) {
key := ptr.Deref(apiKey.Inline, "")
if key == "" {
secretRef := apiKey.SecretRef
secret, err := c.kube.CoreV1().Secrets(namespace).Get(ctx, string(secretRef.Name), metav1.GetOptions{})
if err != nil {
return fmt.Errorf("failed to get secret for API key: %w", err)
return "", fmt.Errorf("failed to get secret for API key: %w", err)
}
if k, ok := secret.Data["apiKey"]; ok {
key = string(k)
} else if key, ok = secret.StringData["apiKey"]; !ok {
return fmt.Errorf("secret %s/%s does not contain 'apiKey' key", namespace, secretRef.Name)
return "", fmt.Errorf("secret %s/%s does not contain 'apiKey' key", namespace, secretRef.Name)
}
}

// Only prepend the "Bearer " prefix if the header is not set or is set to "Authorization".
header := cmp.Or(ptr.Deref(apiKey.Header, ""), "Authorization")
if header == "Authorization" {
credentialValue = fmt.Sprintf("Bearer %s", key)
} else {
credentialValue = key
}

existingSecret, secretErr := c.kube.CoreV1().Secrets(namespace).Get(ctx, secretName, metav1.GetOptions{})
if secretErr != nil && !apierrors.IsNotFound(secretErr) {
return fmt.Errorf("failed to get credential secret: %w", secretErr)
}

secretData := map[string][]byte{
egv1a1.InjectedCredentialKey: []byte(credentialValue),
}

if apierrors.IsNotFound(secretErr) {
secret := &corev1.Secret{
ObjectMeta: metav1.ObjectMeta{
Name: secretName,
Namespace: namespace,
},
Data: secretData,
}

if mcpRoute != nil {
if err := ctrlutil.SetControllerReference(mcpRoute, secret, c.client.Scheme()); err != nil {
return fmt.Errorf("failed to set controller reference for credential secret: %w", err)
}
}

c.logger.Info("Creating credential secret", "namespace", namespace, "name", secretName)
if _, err := c.kube.CoreV1().Secrets(namespace).Create(ctx, secret, metav1.CreateOptions{}); err != nil {
return fmt.Errorf("failed to create credential secret: %w", err)
}
} else if existingSecret.Data == nil || string(existingSecret.Data[egv1a1.InjectedCredentialKey]) != credentialValue {
existingSecret.Data = secretData
c.logger.Info("Updating credential secret", "namespace", namespace, "name", secretName)
if _, err := c.kube.CoreV1().Secrets(namespace).Update(ctx, existingSecret, metav1.UpdateOptions{}); err != nil {
return fmt.Errorf("failed to update credential secret: %w", secretErr)
}
}
return nil
return key, nil
}
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