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External Authorization

Configure the extAuth access strategy in the APIRule custom resource (CR) to define custom authentication and authorization logic.

Request Flow

To expose a workload with an APIRule and an external authorizer, you need the following resources:

  • A Kyma Gateway that configures the Istio Ingress Gateway. You can use the default Kyma Gateway or define your own in any namespace. For details, see Istio Gateways.
  • An APIRule with the extAuth access strategy that references:
    • The Service you want to expose.
    • The Istio Gateway (in this case, Kyma Gateway) to route traffic through.
    • An external authorization provider, configured in the authorizers field.

With this setup, a request is processed as follows:

  1. The client sends an HTTP request with a JWT to the exposed hostname, which enters the cluster through the Istio Ingress Gateway.
  2. Istio Ingress Gateway routes the request to the Service based on the APIRule configuration.
  3. The Istio proxy next to your application sends the authorization request to the configured external authorization provider.
  4. If the external authorization provider allows the request, the Istio proxy forwards the request to the application. If the external authorization provider denies the request, the request does not reach the application.

Minimal Configuration

To use extAuth, you must first define the authorization provider in the Istio configuration, most commonly in the Istio CR. For example, the following Istio CR defines a provider named ext-auth-provider.

apiVersion: operator.kyma-project.io/v1alpha2
kind: Istio
metadata:
  name: default
  namespace: kyma-system
spec:
  config:
    authorizers:
    - headers:
        inCheck:
          include:
          - x-ext-authz
      name: ext-auth-provider
      port: 8000
      service: ext-auth-provider.provider-system.svc.cluster.local

Once you define the provider in the Istio configuration, you can reference it in the APIRule CR. This configuration allows access to the /get path of the user-service service. Based on this APIRule, a CUSTOM Istio AuthorizationPolicy is created with the ext-auth-provider provider, securing access.

apiVersion: gateway.kyma-project.io/v2
kind: APIRule
metadata:
  name: ext-authz
  namespace: user-system
spec:
  hosts:
    - na.example.com
  service:
    name: user-service
    port: 8000
  gateway: kyma-system/kyma-gateway
  rules:
    - path: "/get"
      methods: ["GET"]
      extAuth:
        authorizers:
        - ext-auth-provider

Securing an Endpoint with extAuth and JWT Restrictions

The following configuration allows access to the /get path of the user-service service, as in the example in the previous section. The access is further restricted by the JWT configuration, specified in the restrictions field.

apiVersion: gateway.kyma-project.io/v2
kind: APIRule
metadata:
  name: ext-authz
  namespace: user-system
spec:
  hosts:
    - na.example.com
  service:
    name: user-service
    port: 8000
  gateway: kyma-system/kyma-gateway
  rules:
    - path: "/get"
      methods: ["GET"]
      extAuth:
        authorizers:
          - x-ext-authz
        restrictions:
          authentications:
            - issuer: https://example.com
              jwksUri: https://example.com/.well-known/jwks.json
          authorizations:
            - audiences: ["app1"]