add multicluster gateway solution. (#441)

Signed-off-by: morvencao <lcao@redhat.com>

solutions/multicluster-gateway/README.md

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+# Set up a Multi-Cluster Gateway on OCM
+
+This guide will walk you through setting up a multi-cluster gateway with Open Cluster Management (OCM) using the [Envoy Gateway](https://gateway.envoyproxy.io/). This guide quickly boots three Kind clusters (hub, cluster1, and cluster2) on your local machine. Then, it installs the Gateway API CRDs and Envoy Gateway on the hub cluster. As a prerequisite, we employ [Submariner](https://submariner.io/) to create the multicluster environment, facilitating service export from the hub cluster to managed clusters.
+
+![multicluster-gateway](multicluster-gateway.svg)
+
+## Set up OCM Dev Environment
+
+Set up the dev environment with three Kind clusters (hub, cluster1, and cluster2) in your local machine following [setup dev environment](../setup-dev-environment).
+
+## Connect Clusters with Submariner
+
+Deploy multicluster service API and Submariner for cross-cluster traffic (from hub to managed clusters) using ServiceImport.
+
+Correct the kubeconfig master IP address before deploying Submariner:
+
+```bash
+export HUB_MASTER_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' hub-control-plane)
+export CLUSTER1_MASTER_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' cluster1-control-plane)
+export CLUSTER2_MASTER_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' cluster2-control-plane)
+kubectl config set-cluster kind-hub --server=https://${HUB_MASTER_IP}:6443
+kubectl config set-cluster kind-cluster1 --server=https://${CLUSTER1_MASTER_IP}:6443
+kubectl config set-cluster kind-cluster2 --server=https://${CLUSTER2_MASTER_IP}:6443
+```
+
+Deploy Submariner with globalnet enabled:
+
+```bash
+subctl deploy-broker --context kind-hub --globalnet
+subctl join --context kind-hub broker-info.subm --clusterid hub --natt=false
+subctl join --context kind-cluster1 broker-info.subm --clusterid cluster1 --natt=false
+subctl join --context kind-cluster2 broker-info.subm --clusterid cluster2 --natt=false
+```
+
+## Install Envoy Gateway on Hub Cluster
+
+Install the Gateway API CRDs and Envoy Gateway in hub cluster:
+
+```bash
+helm install eg oci://docker.io/envoyproxy/gateway-helm --version v1.0.1 -n envoy-gateway-system --create-namespace --kube-context kind-hub
+```
+
+Wait for Envoy Gateway to become available:
+
+```bash
+kubectl wait --timeout=5m -n envoy-gateway-system deployment/envoy-gateway --for=condition=Available --context kind-hub
+```
+
+## Deploy Application from Hub:
+
+Deploy and enable the application addon:
+
+```bash
+clusteradm install hub-addon --names application-manager --context kind-hub
+clusteradm addon enable --names application-manager --clusters cluster1,cluster2 --context kind-hub
+kubectl get managedclusteraddon --all-namespaces --context kind-hub
+```
+
+Deploy the nginx application to managed clusters:
+
+```bash
+clusteradm clusterset bind default --namespace default --context kind-hub
+kubectl label managedcluster cluster1 purpose=test --overwrite --context kind-hub
+kubectl label managedcluster cluster2 purpose=test --overwrite --context kind-hub
+kubectl apply -f manifests/nginx-application --context kind-hub
+```
+
+Export the nginx application with subctl command:
+
+```bash
+export NGINX_BACKEND_SERVICE_CLUSTER1=$(oc get svc -n default -l app=nginx-ingress,component=default-backend -o jsonpath='{.items[0].metadata.name}' --context kind-cluster1)
+export NGINX_BACKEND_SERVICE_CLUSTER2=$(oc get svc -n default -l app=nginx-ingress,component=default-backend -o jsonpath='{.items[0].metadata.name}' --context kind-cluster2)
+subctl export service ${NGINX_BACKEND_SERVICE_CLUSTER1} -n default --context kind-cluster1
+subctl export service ${NGINX_BACKEND_SERVICE_CLUSTER2} -n default --context kind-cluster2
+```
+
+## Create Gateway API Objects
+
+Create the Gateway API objects GatewayClass, Gateway and HTTPRoute in hub cluster to set up the routing:
+
+```bash
+sed -i "s|nginx-ingress-1-default-backend|${NGINX_BACKEND_SERVICE_CLUSTER1}|g" manifests/gateway/httproute.yaml
+sed -i "s|nginx-ingress-2-default-backend|${NGINX_BACKEND_SERVICE_CLUSTER2}|g" manifests/gateway/httproute.yaml
+kubectl apply -f manifests/gateway --context kind-hub
+```
+
+## Verify the Multi-Cluster Gateway
+
+Get the name of the Envoy service created the by the example Gateway:
+
+```bash
+export ENVOY_SERVICE=$(kubectl get svc -n envoy-gateway-system --selector=gateway.envoyproxy.io/owning-gateway-namespace=default,gateway.envoyproxy.io/owning-gateway-name=eg -o jsonpath='{.items[0].metadata.name}' --context kind-hub)
+```
+
+Port forward to the Envoy service:
+
+```bash
+kubectl --context kind-hub -n envoy-gateway-system port-forward service/${ENVOY_SERVICE} 8888:80 &
+```
+
+Curl the example nginx default backend through Envoy proxy:
+
+```bash
+curl --verbose --header "Host: www.example.com" http://localhost:8888/healthz
+```

solutions/multicluster-gateway/manifests/gateway/gateway.yaml

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+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  name: eg
+  namespace: default
+spec:
+  gatewayClassName: eg
+  listeners:
+    - name: http
+      protocol: HTTP
+      port: 80

solutions/multicluster-gateway/manifests/gateway/gatewayclass.yaml

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+apiVersion: gateway.envoyproxy.io/v1alpha1
+kind: EnvoyProxy
+metadata:
+  name: custom-proxy-config
+  namespace: envoy-gateway-system
+spec:
+  provider:
+    kubernetes:
+      envoyService:
+        type: ClusterIP
+    type: Kubernetes
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: GatewayClass
+metadata:
+  name: eg
+spec:
+  controllerName: gateway.envoyproxy.io/gatewayclass-controller
+  parametersRef:
+    group: gateway.envoyproxy.io
+    kind: EnvoyProxy
+    name: custom-proxy-config
+    namespace: envoy-gateway-system

solutions/multicluster-gateway/manifests/gateway/httproute.yaml

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+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: backend
+  namespace: default
+spec:
+  parentRefs:
+    - name: eg
+  hostnames:
+    - "www.example.com"
+  rules:
+    - backendRefs:
+        - group: multicluster.x-k8s.io
+          kind: ServiceImport
+          name: nginx-ingress-1-default-backend
+          namespace: default
+          port: 80
+        - group: multicluster.x-k8s.io
+          kind: ServiceImport
+          name: nginx-ingress-2-default-backend
+          namespace: default
+          port: 80
+      matches:
+        - path:
+            type: PathPrefix
+            value: /

solutions/multicluster-gateway/manifests/gateway/referencegrant.yaml

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+apiVersion: gateway.networking.k8s.io/v1beta1
+kind: ReferenceGrant
+metadata:
+  namespace: default
+  name: referencegrant-1
+spec:
+  from:
+    - group: gateway.networking.k8s.io
+      kind: HTTPRoute
+      namespace: default
+  to:
+    - group: multicluster.x-k8s.io
+      kind: ServiceImport

solutions/multicluster-gateway/manifests/nginx-application/channel.yaml

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+apiVersion: apps.open-cluster-management.io/v1
+kind: Channel
+metadata:
+  name: demo-helmrepo
+  namespace: default
+spec:
+    type: HelmRepo
+    pathname: https://charts.helm.sh/stable/
+    insecureSkipVerify: true

solutions/multicluster-gateway/manifests/nginx-application/placement.yaml

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+apiVersion: cluster.open-cluster-management.io/v1beta1
+kind: Placement
+metadata:
+  name: demo-placement
+  namespace: default
+spec:
+  numberOfClusters: 2
+  clusterSets:
+    - default
+  predicates:
+    - requiredClusterSelector:
+        labelSelector:
+          matchLabels:
+            purpose: test

solutions/multicluster-gateway/manifests/nginx-application/subscription.yaml

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+apiVersion: apps.open-cluster-management.io/v1
+kind: Subscription
+metadata:
+  name: demo-subscription
+  namespace: default
+spec:
+  channel: default/demo-helmrepo
+  name: nginx-ingress
+  placement:
+    placementRef:
+      name: demo-placement
+      kind: Placement
+  packageOverrides:
+  - packageName: nginx-lego
+    packageAlias: nginx-lego-simple
+    packageOverrides:
+    - path: spec
+      value:
+        defaultBackend:
+          replicaCount: 1