add gatewayapi support doc

Signed-off-by: AliceProxy <alicewasko@datawire.io>

docs/v0.2.0/design/gatewayapi-support.md

@@ -0,0 +1,76 @@
+# Gateway API Support
+
+As mentioned in the [SystemDesign][] document, Envoy Gateway's managed data plane is configured dynamically through 
+Kubernetes resources, primarily [Gateway API][] objects. Envoy Gateway supports configuration using the following Gateway API resources.
+
+## **GatewayClass**
+
+[GatewayClasses][] are used to configure which Gateways and other reliant resources should be managed by Envoy Gateway.
+
+## **Gateway**
+
+When a [Gateway][] resource is created that references the GatwewayClass Envoy Gateway is managing then Envoy Gateway will 
+create and manage a new Envoy Proxy deployment. All other Gateway API resources that are managed by this Gateway will be used
+to configure the Envoy Proxy deployment that it created.
+
+## **HTTPRoute**
+
+[HTTPRoutes][] are supported as the primary way to configure HTTP traffic in Envoy Gateway.
+All of the following HTTPRoute filters are supported by Envoy Gateway.
+
+- `requestHeaderModifier`: [RequestHeaderModifiers](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.HTTPRouteFilter) can be used to modify or add request headers before the request is proxied to its destination.
+- `responseHeaderModifier`: [ResponseHeaderModifiers](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.HTTPRouteFilter) can be used to modify or add response headers before the response is sent back to the client.
+- `requestMirror`: [RequestMirrors](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.HTTPRouteFilter) configure destinations where the requests should also be mirrored to. Responses to mirrored requests will be ignored.
+- `requestRedirect`: [RequestRedirects](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.HTTPRouteFilter) configure policied for how requests that match the HTTPRoute should be modified and then redirected.
+- `urlRewrite`: [UrlRewrites](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.HTTPRouteFilter) allow for modification of the request's hostname and path before it is proxied to its destination.
+- filters...
+
+**Note:** currently the only kind of [BackendRef][] kind (the destination where traffic should be sent to) that Envoy Gateway supports are Kubernetes services. Routing traffic to other destinations such as arbitrary URLs is not currently possible.
+
+## **TCPRoute**
+
+[TCPRoutes][] are used to configure routing of raw TCP traffic. Traffic can be forwarded to the desired BackendRef(s) based on a port.
+
+**Note:** TCPRoutes only support proxying in non-transparent mode i.e. the backend will see the source IP and port of the deployed
+Envoy instance instead of the client.
+
+## **UDPRoute**
+
+[UDPRoutes][] are used to configure routing of raw UDP traffic. Traffic can be forwarded to the desired BackendRef(s) based on a port.
+
+**Note:** Similar to TCPRoutes, UDPRoutes only support proxying in non-transparent mode i.e. the backend will see the source IP and port of the deployed
+Envoy instance instead of the client.
+
+## **GRPCRoute**
+
+[GRPCRoutes][] configure routing of [gRPC][] requests. They offer request matching by hostname, gRPC service, gRPC method, or HTTP/2 Header.
+Similar to HTTPRoutes, Envoy Gateway supports the following filters on GRPCRoutes to provide additional traffic processing.
+
+- `requestHeaderModifier`: [RequestHeaderModifiers](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.GRPCRouteFilter) can be used to modify or add request headers before the request is proxied to its destination.
+- `responseHeaderModifier`: [ResponseHeaderModifiers](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.GRPCRouteFilter) can be used to modify or add response headers before the response is sent back to the client.
+- `requestMirror`: [RequestMirrors](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.GRPCRouteFilter) configure destinations where the requests should also be mirrored to. Responses to mirrored requests will be ignored.
+
+**Note:** currently the only kind of [BackendRef](https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.GRPCRouteFilter) kind (the destination where traffic should be sent to) that Envoy Gateway supports are Kubernetes services. Routing traffic to other destinations such as arbitrary URLs is not currently possible
+
+## **TLSRoute**
+
+[TLSRoutes][] are used similarly to TCPRoutes to configure routing of TCP traffic; however, unlike TCPRoutes, TLSRoutes can match against TLS-Specific Metadata.
+
+## **ReferenceGrant**
+
+[ReferenceGrants][] are used as a way to configure which resources in other namespaces are allowed to reference specific kinds of resources in
+the namespace of the ReferenceGrant. Normally an HTTPRoute created in namespace `foo` is not allowed to specify a service in the `bar` namespace as the
+one of its BackendRefs. ReferenceGrants are commonly used to permit these types of cross-namespace references.
+
+[SystemDesign]: system-design.md
+[Gateway API]: https://gateway-api.sigs.k8s.io/
+[GatewayClasses]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.GatewayClass
+[Gateway]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.Gateway
+[HTTPRoutes]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.HTTPRoute
+[BackendRef]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1beta1.BackendRef
+[TCPRoutes]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.TCPRoute
+[UDPRoutes]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.UDPRoute
+[GRPCRoutes]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.GRPCRoute
+[gRPC]: https://grpc.io/
+[TLSRoutes]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1alpha2.TLSRoute
+[ReferenceGrants]: https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io%2fv1beta1.ReferenceGrant

docs/v0.2.0/design_docs.rst

@@ -10,3 +10,4 @@ Learn about the internal details of Envoy Gateway.
   design/gatewayapi-translator
   design/watching
   design/config-api
+  design/gatewayapi-support