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Kubernetes Gateway API
Kuma supports Kubernetes Gateway API for configuring built-in gateway as well as traffic routing using the experimental GAMMA routing spec.
Installation
Kubernetes Gateway API is still beta, therefore Kuma’s integration provides the same level of stability.
Gateway API Gateways
aren’t supported in multi-zone. To use the builtin Gateway, you need to use the MeshGateway
resources.
-
Install the Gateway API CRDs.
The Gateway API CRDs aren’t available in Kubernetes by default yet. You must first install the experimental release that includes those CRDs as well as the admission webhook.
-
Enable Gateway API support.
- With
kumactl
, use the--experimental-gatewayapi
flag. - With Helm, use the
experimental.gatewayAPI=true
value.
- With
Gateways
-
Install the counter demo.
kumactl install demo --without-gateway | kubectl apply -f -
-
Add a
Gateway
.The
Gateway
resource represents the proxy instance that handles traffic for a set of Gateway API routes.Every
Gateway
refers to aGatewayClass
. TheGatewayClass
represents the class ofGateway
, in this case Kuma’s builtin edge gateway, and points to a controller that should manage theseGateways
. It can also hold additional configuration.For Helm and
kumactl
installations, aGatewayClass
namedkuma
is automatically installed if the Gateway API CRDs are present.echo "apiVersion: gateway.networking.k8s.io/v1beta1 kind: Gateway metadata: name: kuma namespace: kuma-demo spec: gatewayClassName: kuma listeners: - name: proxy port: 8080 protocol: HTTP " | kubectl apply -f -
When a user applies a
Gateway
resource, Kuma automatically creates aDeployment
of built-in gateways with a correspondingService
.kubectl get pods -n kuma-demo NAME READY STATUS RESTARTS AGE redis-59c9d56fc-6gcbc 2/2 Running 0 2m8s demo-app-5845d6447b-v7npw 2/2 Running 0 2m8s kuma-4j6wr-58998b5576-25wl6 1/1 Running 0 30s kubectl get svc -n kuma-demo NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE redis ClusterIP 10.43.223.223 <none> 6379/TCP 3m27s demo-app ClusterIP 10.43.216.203 <none> 5000/TCP 3m27s kuma-pfh4s LoadBalancer 10.43.122.93 172.20.0.3 8080:30627/TCP 87s
The
Gateway
is now accessible using the external address172.20.0.3:8080
. -
Add an
HTTPRoute
.HTTPRoute
resources contain a set of matching criteria for HTTP requests and upstreamServices
to route those requests to.echo "apiVersion: gateway.networking.k8s.io/v1beta1 kind: HTTPRoute metadata: name: echo namespace: kuma-demo spec: parentRefs: - group: gateway.networking.k8s.io kind: Gateway name: kuma namespace: kuma-demo rules: - backendRefs: - kind: Service name: demo-app port: 5000 weight: 1 matches: - path: type: PathPrefix value: / " | kubectl apply -f -
After creating an
HTTPRoute
, accessing/
forwards a request to the demo app:curl 172.20.0.3:8080/ -i
HTTP/1.1 200 OK x-powered-by: Express accept-ranges: bytes cache-control: public, max-age=0 last-modified: Tue, 20 Oct 2020 17:16:41 GMT etag: W/"2b91-175470350a8" content-type: text/html; charset=UTF-8 content-length: 11153 date: Fri, 18 Mar 2022 11:33:29 GMT x-envoy-upstream-service-time: 2 server: Kuma Gateway <html> <head> ...
TLS termination
Gateway API supports TLS termination by using standard kubernetes.io/tls
Secrets.
Here is an example
apiVersion: v1
kind: Secret
metadata:
name: secret-tls
namespace: kuma-demo
type: kubernetes.io/tls
data:
tls.crt: "MIIEOzCCAyO..." # redacted
tls.key: "MIIEowIBAAKC..." # redacted
apiVersion: gateway.networking.k8s.io/v1beta1
kind: Gateway
metadata:
name: kuma
namespace: kuma-demo
spec:
gatewayClassName: kuma
listeners:
- name: proxy
port: 8080
hostname: test.kuma.io
protocol: HTTPS
tls:
certificateRefs:
- name: secret-tls
Under the hood, Kuma CP copies the Secret
to kuma-system
namespace and converts it to
Kuma secret
.
It tracks all the changes to the secret and deletes it upon deletion of the original secret.
Customization
Gateway API provides the parametersRef
field on GatewayClass.spec
to provide additional, implementation-specific configuration to Gateways
.
When using Gateway API with Kuma, you can refer to a MeshGatewayConfig
resource:
apiVersion: gateway.networking.k8s.io/v1beta1
kind: GatewayClass
metadata:
name: kuma
spec:
controllerName: gateways.kuma.io/controller
parametersRef:
kind: MeshGatewayConfig
group: kuma.io
name: kuma
This resource has the same structure as the MeshGatewayInstance
resource
except that the tags
field is optional.
With a MeshGatewayConfig
you can then customize
the generated Service
and Deployment
resources.
Multi-mesh
You can specify a Mesh
for Gateway
and HTTPRoute
resources
by setting the kuma.io/mesh
annotation
Note that HTTPRoutes
must also have the annotation to reference a
Gateway
from a non-default Mesh
.
Cross-mesh
Cross-mesh gateways are supported with Gateway API.
You’ll just need to create a corresponding GatewayClass
pointing to a MeshGatewayConfig
that
sets crossMesh: true
:
---
apiVersion: gateway.networking.k8s.io/v1beta1
kind: GatewayClass
metadata:
name: kuma-cross-mesh
spec:
controllerName: gateways.kuma.io/controller
parametersRef:
group: kuma.io
kind: MeshGatewayConfig
name: default-cross-mesh
---
apiVersion: kuma.io/v1alpha1
kind: MeshGatewayConfig
metadata:
name: default-cross-mesh
spec:
crossMesh: true
and then reference it in your Gateway
:
apiVersion: gateway.networking.k8s.io/v1beta1
kind: Gateway
metadata:
name: kuma
namespace: default
spec:
gatewayClassName: kuma-cross-mesh
Multi-zone
Gateway API isn’t supported with multi-zone deployments, use Kuma’s MeshGateways
/MeshGatewayRoutes
instead.
Service to service routing
Kuma also supports routing between services with
HTTPRoute
in conformance with
the GAMMA specifications.
GAMMA is a Gateway API subproject focused on mesh implementations of Gateway API and extending the Gateway API resources to mesh use cases.
GAMMA itself as well as GAMMA in Kuma are experimental!
The key feature of HTTPRoute
for mesh routing is specifying a Kubernetes
Service
as the parentRef
, as opposed to a Gateway
.
All requests to this Service
are then filtered and routed as specified in the
HTTPRoute
.
apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
name: canary-demo-app
namespace: kuma-demo
spec:
parentRefs:
- name: demo-app
port: 5000
kind: Service
rules:
- backendRefs:
- name: demo-app-v1
port: 5000
- name: demo-app-v2
port: 5000
The namespace of the HTTPRoute
is key. If the route’s namespace and the
parentRef
’s namespace are identical, Kuma applies
the route to requests from all workloads.
If the route’s namespace differs from its parentRef
’s namespace,
the HTTPRoute
applies only to requests
from workloads in the route’s namespace.
Remember to tag your Service
ports with appProtocol: http
to use
them in an HTTPRoute
!
Because of how Kuma maps resources at the moment,
the combination of the HTTPRoute
s name and namespace and
the parent Service
name and namespace must be no more than 249 characters.
How it works
Kuma includes controllers that reconcile Gateway API CRDs and convert them into the corresponding Kuma CRDs.
This is why in the GUI, Kuma MeshGateways
/MeshGatewayRoutes
/MeshHTTPRoutes
are visible and not Kubernetes Gateway API resources.
Kubernetes Gateway API resources serve as the source of truth for Kuma gateways and routes. Any edits to the corresponding Kuma resources are overwritten.