Gateway

    Kuma Gateway deploys as a Kuma Dataplane , that’s an instance of the process. Like all Kuma Dataplanes, the Kuma Gateway Dataplane manages an Envoy proxy process that does the actual network traffic proxying.

    You can distinguish two types of gateways:

    • delegated: Allows users to use any existing gateway like .
    • builtin: Configures the data plane proxy to expose external listeners to drive traffic inside the mesh.

    Gateways exist within a mesh. If you have multiple meshes, each mesh requires its own gateway. You can easily connect your meshes together using cross-mesh gateways.

    Below visualization shows the difference between delegated and builtin gateways:

    Builtin with Kong Gateway to handle the inbound traffic:

    Delegated with Kong Gateway:

    Gateway - 图2

    The blue lines represent traffic not managed by Kuma, which needs configuring in the Gateway.

    The Dataplane entity can operate in gateway mode. This way you can integrate Kuma with existing API Gateways like Kong.

    The gateway mode lets you skip exposing inbound listeners so it won’t be intercepting ingress traffic. When you use a data plane proxy with a service, both inbound traffic to a service and outbound traffic from the service flows through the proxy. In the gateway mode, you want inbound traffic to go directly to the gateway, otherwise, clients require dynamically generated certificates for communication between services within the mesh. The gateway itself should handle security at an entrance to the mesh.

    Kuma supports most of the ingress controllers. However, the recommended gateway in Kubernetes is Kong. You can use to implement authentication, transformations, and other functionalities across Kubernetes clusters with zero downtime. Most ingress controllers require an annotation ingress.kubernetes.io/service-upstream=true on every Kubernetes Service to work with Kuma. Kuma automatically injects the annotation for every Service in a namespace in a mesh that has kuma.io/sidecar-injection: enabled label.

    To use the delegated gateway feature, mark your API Gateway’s Pod with the kuma.io/gateway: enabled annotation. Control plane automatically generates Dataplane objects.

    For example:

    API Gateway receives Services from:

    • one specific zone
    • multi-zone

    Multi-zone requires exposing a dedicated Kubernetes Service object with type ExternalName. Control plane creates a DNS entry externalName with suffix .mesh, which Kuma resolves in internal .

    Example setting up Kong Ingress Controller

    Follow instructions to setup an echo service reachable through Kong. These instructions are mostly taken from the .

    1. Install Kuma on your cluster and have the default .

    2. Install Kong using helm.

    3. Start an echo-service:

      1. kubectl apply -f https://bit.ly/echo-service

    4. Add an ingress:

      1. echo "
      2. apiVersion: networking.k8s.io/v1
      3. kind: Ingress
      4. metadata:
      5.   name: demo
      6. spec:
      7.   ingressClassName: kong
      8.   rules:
      9.   - http:
      10.       paths:
      11.       - path: /foo
      12.         pathType: ImplementationSpecific
      13.         backend:
      14.           service:
      15.             name: echo
      16.             port:
      17.               number: 80
      18. " | kubectl apply -f -

    You can check that the sidecar is running by checking the number of containers in each pod:

    1. kubectl get pods
    2. NAME                                    READY   STATUS    RESTARTS   AGE
    3. echo-5fc5b5bc84-zr9kl                   2/2     Running   0          41m
    4. kong-1645186528-kong-648b9596c7-f2xfv   3/3     Running   2          40m

    Example Gateway in Multi-Zone

    In the previous example, you setup an echo, that’s running on port 80, and deployed in the default namespace.

    Now make sure that this service works correctly with multi-zone. In order to do so, create Service manually:

    1. echo "
    2. apiVersion: v1
    3. kind: Service
    4. metadata:
    5.   name: echo-multizone
    6.   namespace: default
    7. spec:
    8.   type: ExternalName
    9.   externalName: echo.default.svc.80.mesh
    10. " | kubectl apply -f -

    Finally, you need to create a corresponding Kubernetes Ingress that routes /bar to the multi-zone service:

    1. echo "
    2. apiVersion: networking.k8s.io/v1
    3. kind: Ingress
    4. metadata:
    5.   name: demo-multizone
    6.   namespace: default
    7. spec:
    8.   ingressClassName: kong
    9.   rules:
    10.     - http:
    11.         paths:
    12.           - path: /bar
    13.             pathType: ImplementationSpecific
    14.             backend:
    15.               service:
    16.                 name: echo-multizone
    17.                 port:
    18. " | kubectl apply -f -

    Note that since you are addressing the service by its domain name echo.default.svc.8080.mesh, you should always refer to port 80. This port is only a placeholder and is automatically replaced with the actual port of the service.

    If you want to expose a Service in one zone only, as opposed to multi-zone, you can just use the service name in the Ingress definition without having to create an externalName entry, this is what you did in your first example.

    For an in-depth example on deploying Kuma with Kong for Kubernetes, please follow this .

    On Universal, you can define the Dataplane entity like this:

    When configuring your API Gateway to pass traffic to backend set the url to http://localhost:33033

    Builtin

    The builtin gateway is integrated into the core Kuma control plane. You can configure gateway listeners and routes to service directly using Kuma policies.

    The builtin gateway is configured on a Dataplane:

    1. type: Dataplane
    2. mesh: default
    3. name: gateway-instance-1
    4. networking:
    5.   address: 127.0.0.1
    6.   gateway:
    7.     type: BUILTIN
    8.     tags:
    9.       kuma.io/service: edge-gateway

    A builtin gateway Dataplane does not have either inbound or outbound configuration.

    To configure your gateway Kuma has these resources:

    • is used to configure listeners exposed by the gateway
    • MeshGatewayRoute is used to configure route to route traffic from listeners to other services.

    Kuma gateways are configured with the .

    Usage

    You can create and configure a gateway that listens for traffic from outside of your mesh and forwards it to the .

    To ease starting gateways on Kubernetes, Kuma comes with a builtin type .

    This resource launches kuma-dp in your cluster. If you are running a multi-zone Kuma, MeshGatewayInstance needs to be created in a specific zone, not the global cluster. See the dedicated section for using builtin gateways on multi-zone.

    This type requests that the control plane create and manage a Kubernetes Deployment and Service suitable for providing service capacity for the MeshGateway with the matching kuma.io/service tag.

    1. echo "
    2. apiVersion: kuma.io/v1alpha1
    3. kind: MeshGatewayInstance
    4. metadata:
    5.   name: edge-gateway
    6.   namespace: default
    7. spec:
    8.   replicas: 1
    9.   serviceType: LoadBalancer
    10.   tags:
    11.     kuma.io/service: edge-gateway
    12. " | kubectl apply -f -

    Once a MeshGateway exists that matches the kuma.io/service tag, the control plane creates a new Deployment in the default namespace. This Deployment has the requested number of builtin gateway Dataplane pod replicas running as the service named in the MeshGatewayInstance tags. The control plane also creates a new Service to send network traffic to the builtin Dataplane pods. The Service is of the type requested in the MeshGatewayInstance, and its ports are automatically adjusted to match the listeners on the corresponding MeshGateway.

    Customization

    Additional customization of the generated Service or Deployment is possible via MeshGatewayInstance.spec. For example, you can add annotations to the generated Service:

    1. spec:
    2.   replicas: 1
    3.   serviceType: LoadBalancer
    4.   tags:
    5.     kuma.io/service: edge-gateway
    6.   resources:
    7.     limits: ...
    8.     requests: ...
    9.   serviceTemplate:
    10.     metadata:
    11.       annotations:
    12.         service.beta.kubernetes.io/aws-load-balancer-internal: "true"
    13.         ...
    14.     spec:
    15.       loadBalancerIP: ...
    16. " | kubectl apply -f -

    The first thing you’ll need is to create a Dataplane object for your gateway:

    1. type: Dataplane
    2. mesh: default
    3. name: gateway-instance-1
    4. networking:
    5.   address: 127.0.0.1
    6.   gateway:
    7.     type: BUILTIN
    8.     tags:
    9.       kuma.io/service: edge-gateway

    As you’re in universal you now need to run kuma-dp:

    1. kuma-dp run \
    2.   --cp-address=https://localhost:5678/ \
    3.   --dns-enabled=false \
    4.   --dataplane-token-file=kuma-token-gateway \ # this needs to be generated like for regular Dataplane
    5.   --dataplane-file=my-gateway.yaml # the Dataplane resource described above

    Now let’s create a MeshGateway to configure the listeners:

    1. type: MeshGateway
    2. mesh: default
    3. name: edge-gateway
    4. selectors:
    5.   - match:
    6.       kuma.io/service: edge-gateway
    7. conf:
    8.   listeners:
    9.     - port: 8080
    10.       protocol: HTTP
    11.       hostname: foo.example.com
    12.       tags:
    13.         port: http/8080

    The MeshGateway creates a listener on port 8080 and will accept any traffic which has the Host header set to foo.example.com. Notice that listeners have tags like Dataplanes. This will be useful when binding routes to listeners.

    These are Kuma policies so if you are running on multi-zone they need to be created on the Global CP. See the dedicated section for using builtin gateways on multi-zone.

    Now, you can define a MeshGatewayRoute to forward your traffic based on the matched URL path.

    1. echo "
    2. kind: MeshGatewayRoute
    3. mesh: default
    4. metadata:
    5.   name: edge-gateway-route
    6. spec:
    7.   selectors:
    9.         kuma.io/service: edge-gateway
    10.         port: http/8080
    11.   conf:
    12.     http:
    13.       rules:
    14.         - matches:
    15.             - path:
    16.                 match: PREFIX
    17.                 value: /
    18.           backends:
    19.             - destination:
    20.                 kuma.io/service: demo-app_kuma-demo_svc_5000
    21. " | kubectl apply -f -
    1. type: MeshGatewayRoute
    2. mesh: default
    3. name: edge-gateway-route
    4. selectors:
    5.   - match:
    6.       kuma.io/service: edge-gateway
    7.       port: http/8080
    8. conf:
    9.   http:
    10.     rules:
    11.       - matches:
    12.           - path:
    13.               match: PREFIX
    14.               value: /
    15.         backends:
    16.           - destination:
    17.               kuma.io/service: demo-app_kuma-demo_svc_5000

    The builtin gateway also supports TCP MeshGatewayRoutes:

    1. type: MeshGateway
    2. mesh: default
    3. name: edge-gateway
    4. selectors:
    5.   - match:
    6.       kuma.io/service: edge-gateway
    7. conf:
    8.   listeners:
    9.     - port: 8080
    10.       protocol: TCP
    11.       tags:
    12.         port: tcp/8080
    13. ---
    14. type: MeshGatewayRoute
    15. mesh: default
    16. name: edge-gateway-route
    17. selectors:
    18.   - match:
    19.       kuma.io/service: edge-gateway
    20.       port: tcp/8080
    21. conf:
    22.   tcp:
    23.     rules:
    24.       - backends:
    25.           - destination:
    26.               kuma.io/service: redis_kuma-demo_svc_6379

    The TCP configuration only supports the backends key (no matches or filters). There are no TCP-generic ways to filter or match traffic so it can only load balance.

    Multi-zone

    The Kuma Gateway resource types, MeshGateway and MeshGatewayRoute, are synced across zones by the Kuma control plane. If you have a multi-zone deployment, follow existing Kuma practice and create any Kuma Gateway resources in the global control plane. Once these resources exist, you can provision serving capacity in the zones where it is needed by deploying builtin gateway Dataplanes (in Universal zones) or MeshGatewayInstances (Kubernetes zones).

    See the for a refresher.

    The Mesh abstraction allows users to encapsulate and isolate services inside a kind of submesh with its own CA. With a cross-mesh MeshGateway, you can expose the services of one Mesh to other Meshes by defining an API with MeshGatewayRoutes. All traffic remains inside the Kuma data plane protected by mTLS.

    All meshes involved in cross-mesh communication must have mTLS enabled. To enable cross-mesh functionality for a MeshGateway listener, set the crossMesh property.

    1.   ...
    2.   mesh: default
    3.   selectors:
    4.     - match:
    5.         kuma.io/service: cross-mesh-gateway
    6.   conf:
    7.     listeners:
    8.       - port: 8080
    9.         protocol: HTTP
    10.         crossMesh: true
    11.         hostname: default.mesh

    Hostname

    If the listener includes a hostname value, the cross-mesh listener will be reachable from all Meshes at this hostname and port. In this case, the URL http://default.mesh:8080.

    Otherwise it will be reachable at the host: internal.<gateway-name>.<mesh-of-gateway-name>.mesh.

    Without transparent proxy

    If transparent proxy isn’t set up, you’ll have to add the listener explicitly as an outbound to your Dataplane objects if you want to access it:

    Limitations

    Cross-mesh functionality isn’t supported across zones at the moment but will be in a future release.

    The only protocol supported is HTTP. Like service to service traffic, all traffic to the gateway is protected with mTLS but appears to be HTTP traffic to the applications inside the mesh. In the future, this limitation may be relaxed.

    There can be only one entry in selectors for a MeshGateway with crossMesh: true.

    Policy support

    Not all Kuma policies are applicable to Kuma Gateway (see table below). Kuma connection policies are selected by matching the source and destination expressions against sets of Kuma tags. In the case of Kuma Gateway the source selector is always matched against the Gateway listener tags, and the destination expression is matched against the backend destination tags configured on a Gateway Route.

    When a Gateway Route forwards traffic, it may weight the traffic across multiple services. In this case, matching the destination for a connection policy becomes ambiguous. Although the traffic is proxied to more than one distinct service, Kuma can only configure the route with one connection policy. In this case, Kuma employs some simple heuristics to choose the policy. If all the backend destinations refer to the same service, Kuma will choose the oldest connection policy that has a matching destination service. However, if the backend destinations refer to different services, Kuma will prefer a connection policy with a wildcard destination (i.e. where the destination service is ).

    Kuma may select different connection policies of the same type depending on the context. For example, when Kuma configures an Envoy route, there may be multiple candidate policies (due to the traffic splitting across destination services), but when Kuma configures an Envoy cluster there is usually only a single candidate (because clusters are defined to be a single service). This can result in situations where different policies (of the same type) are used for different parts of the Envoy configuration.

    You can find in each policy’s dedicated information with regard to builtin gateway support.