SecurityPolicy

Before you Begin

• Gateway API Extensions

Overview

SecurityPolicy is an Envoy Gateway extension to the Kubernetes Gateway API that allows you to define authentication and authorization requirements for traffic entering your gateway. It acts as a security layer that only properly authenticated and authorized requests are allowed through your backend services.

SecurityPolicy is designed for you to enforce access controls through configuration at the edge of your infrastructure in a declarative, Kubernetes-native way, without needing to configure complex proxy rules manually.

Use Cases

1. Authentication Methods:

   • Authenticate client apps using mTLS, JWTs, API keys, or Basic Auth
   • Authenticate users with OIDC Provider integration

2. Authorization Controls:

   • Define and enforce authorization rules based on user roles and permissions
   • Integrate with external authorization services for real-time policy decisions
   • JWT Token Authorization Checks

3. Cross-Origin Security:

   • Configure CORS to allow or restrict cross-origin requests for APIs

SecurityPolicy in Envoy Gateway

SecurityPolicy is implemented as a Kubernetes Custom Resource Definition (CRD) and follows the policy attachment model.

Targets

SecurityPolicy can be attached to Gateway API resources using two targeting mechanisms:

1. Direct Reference (targetRefs): Explicitly reference specific resources by name and kind.
2. Label Selection (targetSelectors): Match resources based on their labels (see targetSelectors API reference)

The policy applies to all resources that match either targeting method. You can target various Gateway API resource types including Gateway, HTTPRoute, and GRPCRoute.

Important: A SecurityPolicy can only target resources in the same namespace as the policy itself.

Precedence

When multiple SecurityPolicies apply to the same resource, Envoy Gateway resolves conflicts using a precedence hierarchy based on the target resource type and section-level specificity:

1. Route rule-level policies (HTTPRoute/GRPCRoute with sectionName targeting specific rules) - Highest precedence
2. Route-level policies (HTTPRoute, GRPCRoute without sectionName) - High precedence
3. Listener-level policies (Gateway with sectionName targeting specific listeners) - Medium precedence
4. Gateway-level policies (Gateway without sectionName) - Lowest precedence

Multiple Policies at the Same Level

When multiple SecurityPolicies target the same resource at the same hierarchy level (e.g., multiple policies targeting the same HTTPRoute), Envoy Gateway uses the following tie-breaking rules:

1. Creation Time Priority: The oldest policy (earliest creationTimestamp) takes precedence
2. Name-based Sorting: If policies have identical creation timestamps, they are sorted alphabetically by namespaced name, with the first policy taking precedence

# Policy created first - takes precedence
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: alpha-policy
  creationTimestamp: "2023-01-01T10:00:00Z"
spec:
  targetRefs:
    - kind: HTTPRoute
      name: my-route
  cors:
    allowOrigins:
      - exact: https://example.com

---
# Policy created later - lower precedence
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: beta-policy
  creationTimestamp: "2023-01-01T11:00:00Z"
spec:
  targetRefs:
    - kind: HTTPRoute
      name: my-route
  cors:
    allowOrigins:
      - exact: https://different.com

In this example, alpha-policy would take precedence due to its earlier creation time, so the HTTPRoute would use the CORS setting from alpha-policy.

# HTTPRoute with named rules
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: my-route
spec:
  rules:
  - name: rule-1  # Named rule for sectionName targeting
    matches:
    - path:
        value: "/api"
    backendRefs:
    - name: api-service
      port: 80

---
# Route rule-level policy (highest precedence)
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: rule-policy
spec:
  targetRef:
    kind: HTTPRoute
    name: my-route
    sectionName: rule-1  # Targets specific named rule
  cors:
    allowOrigins:
    - exact: https://rule.example.com

---
# Route-level policy (high precedence)
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: route-policy
spec:
  targetRef:
    kind: HTTPRoute
    name: my-route  # No sectionName = entire route
  cors:
    allowOrigins:
    - exact: https://route.example.com

---
# Listener-level policy (medium precedence)
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: listener-policy
spec:
  targetRef:
    kind: Gateway
    name: my-gateway
    sectionName: https-listener  # Targets specific listener
  cors:
    allowOrigins:
    - exact: https://listener.example.com

---
# Gateway-level policy (lowest precedence)
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: gateway-policy
spec:
  targetRef:
    kind: Gateway
    name: my-gateway  # No sectionName = entire gateway
  cors:
    allowOrigins:
    - exact: https://gateway.example.com

In this example, the specific rule rule-1 within HTTPRoute my-route would use the CORS settings from the route rule-level policy (https://rule.example.com), overriding the route-level, listener-level, and gateway-level settings.

For section-specific targeting, consider these policies with different hierarchy levels targeting the same Gateway:

# Policy A: Applies to a specific listener
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: listener-policy
  namespace: default
spec:
  targetRefs:
    - kind: Gateway
      name: my-gateway
      sectionName: https  # Applies only to "https" listener
  cors:
    allowOrigins:
      - exact: https://example.com
---
# Policy B: Applies to the entire gateway
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: SecurityPolicy
metadata:
  name: gateway-policy
  namespace: default
spec:
  targetRefs:
    - kind: Gateway
      name: my-gateway  # Applies to all listeners
  cors:
    allowOrigins:
      - exact: https://default.com

In the example, policy A affects only the HTTPS listener, while policy B applies to the rest of the listeners in the gateway. Since Policy A is more specific, the system will show Overridden=True for Policy B on the https listener.

Related Resources

• API Key Authentication
• Basic Authentication
• CORS
• External Authorization
• IP Allowlist/Denylist
• JWT Authentication
• JWT Claim Based Authorization
• OIDC Authorization
• SecurityPolicy API Reference