add a solution to deploy argocd apps

Signed-off-by: Yang Le <yangle@redhat.com>

solutions/deploy-argocd-apps/README.md

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+# Deploy applications with Argo CD
+
+The script and instructions provided in this doc help you to setup an Open Cluster Management (OCM) environment with Kind clusters and integrate it with Argo CD. And then you can deploy Argo CD applications to OCM managed clusters.
+
+## Prerequisite
+
+- [kind](https://kind.sigs.k8s.io) must be installed on your local machine. The Kubernetes version must be >= 1.19, see [kind user guide](https://kind.sigs.k8s.io/docs/user/quick-start/#creating-a-cluster) for more details.
+
+- Download and install [clusteradm](https://github.com/open-cluster-management-io/clusteradm/releases). For Linux OS, run the following commands:
+
+    ```
+    wget -qO- https://github.com/open-cluster-management-io/clusteradm/releases/latest/download/clusteradm_linux_amd64.tar.gz | sudo tar -xvz -C /usr/local/bin/
+
+    sudo chmod +x /usr/local/bin/clusteradm
+    ```
+
+## Setup the clusters
+
+1. Edit the kind configuration files, including `cluster1-config.yaml` and `cluster2-config.yaml`, for managed clusters to update the value in `apiServerAddress` to match your private IP address, which makes the kube apiserver of the managed clusters accessable for Argo CD running on the hub cluster. 
+
+2. Run `./setup-ocm.sh`, you will see two clusters registered on the hub cluster.
+
+    ```
+    NAME       HUB ACCEPTED   MANAGED CLUSTER URLS                  JOINED   AVAILABLE   AGE
+    cluster1   true           https://cluster1-control-plane:6443                        18s
+    cluster2   true           https://cluster2-control-plane:6443                        1s
+    ```
+
+## Install Argo CD
+
+1. Install Argo CD on the OCM hub cluster
+
+    ```bash
+    kubectl create namespace argocd
+    kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml
+    ```
+
+    See more informatin from [Argo CD Getting Started](https://argo-cd.readthedocs.io/en/stable/getting_started/).
+
+2. Confirm that all pods are running.
+
+    ```bash
+    $ kubectl -n argocd get pods
+    argocd-application-controller-0                    1/1     Running        0          22s
+    argocd-applicationset-controller-7f466f7cc-9hdlq   1/1     Running        0          22s
+    argocd-dex-server-54cd4596c4-t5sb5                 1/1     Running        0          22s
+    argocd-notifications-controller-8445d56d96-8745z   1/1     Running        0          22s
+    argocd-redis-65596bf87-lkrg2                       1/1     Running        0          22s
+    argocd-repo-server-5ccf4bd568-hxlzw                1/1     Running        0          22s
+    argocd-server-7dff66c8f8-qxzp9                     1/1     Running        0          22s
+    ```
+
+3. Download Argo CD CLI
+
+    Download the latest version of Argo CD CLI `argocd` from https://github.com/argoproj/argo-cd/releases/latest. More detailed installation instructions can be found via the [CLI installation documentation](https://argo-cd.readthedocs.io/en/stable/cli_installation/).
+
+## Integrate OCM with Argo CD
+
+1. Start port forwarding to expose Argo CD API server on the hub cluster.
+
+    ```bash
+    kubectl port-forward svc/argocd-server -n argocd 8080:443
+    ```
+
+2. Run `./setup-argocd.sh`, you will see two clusters registered on Argo CD.
+
+    ```
+    SERVER                          NAME        VERSION  STATUS      MESSAGE
+    https://10.0.109.2:11443        cluster2    1.23     Successful  
+    https://10.0.109.2:10443        cluster1    1.23     Successful 
+    ```
+
+## Deploy an application to managed clusters
+
+1. Create a placement to select a set of managed clusters. 
+
+    ```bash
+    kubectl apply -f ./manifests/guestbook-app-placement.yaml
+    ```
+
+    Confirm the the placemet selects all managed clusters. 
+
+    ```bash
+    $ kubectl -n argocd get placementdecisions -l cluster.open-cluster-management.io/placement=guestbook-app-placement -o yaml
+    apiVersion: v1
+    items:
+    - apiVersion: cluster.open-cluster-management.io/v1beta1
+      kind: PlacementDecision
+      metadata:
+        labels:
+          cluster.open-cluster-management.io/placement: guestbook-app-placement
+        name: guestbook-app-placement-decision-1
+        namespace: argocd
+      status:
+        decisions:
+        - clusterName: cluster1
+          reason: ""
+        - clusterName: cluster2
+          reason: ""
+    kind: List
+    metadata:
+      resourceVersion: ""
+      selfLink: ""
+    ```
+
+2. Create an Argo CD `ApplicationSet`.
+
+    ```bash
+    kubectl apply -f ./manifests/guestbook-app.yaml
+    ```
+
+    With references to the OCM Placement generator, `argocd/ocm-placement-generator`, and a placement, an `ApplicationSet` can target the application to the clusters selected by the placement.
+
+3. Confirm the `ApplicationSet` is created and an `Application` is generated for each selected managed cluster.
+
+    ```bash
+    $ kubectl -n argocd get applicationsets
+    NAME            AGE
+    guestbook-app   4s
+
+    $ kubectl -n argocd get applications
+    NAME                     SYNC STATUS   HEALTH STATUS
+    cluster1-guestbook-app   Synced        Progressing
+    cluster2-guestbook-app   Synced        Progressing
+    ```
+
+4. Confirm the `Application` is running on the selected managed clusters
+
+    ```bash
+    $ kubectl --context kind-cluster1 -n guestbook get pods
+    NAME                           READY   STATUS    RESTARTS   AGE
+    guestbook-ui-6b689986f-cdrk8   1/1     Running   0          112s
+
+    $ kubectl --context kind-cluster2 -n guestbook get pods
+    NAME                           READY   STATUS    RESTARTS   AGE
+    guestbook-ui-6b689986f-x9tsq   1/1     Running   0          2m33s
+    ```

solutions/deploy-argocd-apps/cluster1-config.yaml

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+# cluster1-config.yaml
+kind: Cluster
+apiVersion: kind.x-k8s.io/v1alpha4
+networking:
+   # replace the IP address with your real IP address
+  apiServerAddress: "192.168.1.123"
+  apiServerPort: 10443

solutions/deploy-argocd-apps/cluster2-config.yaml

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+# cluster2-config.yaml
+kind: Cluster
+apiVersion: kind.x-k8s.io/v1alpha4
+networking:
+  # replace the IP address with your real IP address
+  apiServerAddress: "192.168.1.123"
+  apiServerPort: 11443

solutions/deploy-argocd-apps/manifests/guestbook-app-placement.yaml

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+apiVersion: cluster.open-cluster-management.io/v1beta1
+kind: Placement
+metadata:
+  name: guestbook-app-placement
+  namespace: argocd
+spec: {}

solutions/deploy-argocd-apps/manifests/guestbook-app.yaml

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+apiVersion: argoproj.io/v1alpha1
+kind: ApplicationSet
+metadata:
+  name: guestbook-app
+  namespace: argocd
+spec:
+  generators:
+    - clusterDecisionResource:
+        configMapRef: ocm-placement-generator
+        labelSelector:
+          matchLabels:
+            cluster.open-cluster-management.io/placement: guestbook-app-placement
+        requeueAfterSeconds: 30
+  template:
+    metadata:
+      name: '{{clusterName}}-guestbook-app'
+    spec:
+      project: default
+      source:
+        repoURL: 'https://github.com/argoproj/argocd-example-apps.git'
+        targetRevision: HEAD
+        path: guestbook
+      destination:
+        name: '{{clusterName}}'
+        namespace: guestbook
+      syncPolicy:
+        automated:
+          prune: true
+        syncOptions:
+          - CreateNamespace=true

solutions/deploy-argocd-apps/manifests/ocm-placement-consumer-role.yaml

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+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: ocm-placement-consumer
+  namespace: argocd
+rules:
+# Allow controller to manage placements/placementdecisions
+- apiGroups: ["cluster.open-cluster-management.io"]
+  resources: ["placements"]
+  verbs: ["get", "list"]
+- apiGroups: ["cluster.open-cluster-management.io"]
+  resources: ["placementdecisions"]
+  verbs: ["get", "list"]

solutions/deploy-argocd-apps/manifests/ocm-placement-consumer-rolebinding.yaml

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+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: ocm-placement-consumer:argocd
+  namespace: argocd
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: ocm-placement-consumer
+subjects:
+- kind: ServiceAccount
+  namespace: argocd
+  name: argocd-applicationset-controller

solutions/deploy-argocd-apps/manifests/ocm-placement-generator-cm.yaml

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+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: ocm-placement-generator
+  namespace: argocd
+data:
+  apiVersion: cluster.open-cluster-management.io/v1beta1
+  kind: placementdecisions
+  statusListKey: decisions
+  matchKey: clusterName

solutions/deploy-argocd-apps/setup-argocd.sh

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+#!/bin/bash
+set -e
+
+# login to Argo CD
+echo "Login to Argo CD"
+admin_pass=$(kubectl -n argocd get secret argocd-initial-admin-secret -o=jsonpath='{.data.password}' | base64 -d)
+argocd login localhost:8080 --username=admin --password="${admin_pass}" --insecure
+
+# register the two OCM managed clusters to Argo CD
+echo "Register cluster1 and cluster2 to Argo CD"
+argocd cluster add kind-cluster1 --name=cluster1
+argocd cluster add kind-cluster2 --name=cluster2
+
+# grant permission to Argo CD to access OCM placement API
+echo "Grant permission to Argo CD to access OCM placement API"
+kubectl apply -f ./manifests/ocm-placement-consumer-role.yaml
+kubectl apply -f ./manifests/ocm-placement-consumer-rolebinding.yaml
+
+# bind the global clusterset which includes all OCM managed clusters to argocd namespace
+echo "Bind the global clusterset to argocd namespace"
+clusteradm clusterset bind global --namespace argocd
+
+# create the configuration of the OCM Placement generator
+echo "Create the OCM Placement generator"
+kubectl apply -f ./manifests/ocm-placement-generator-cm.yaml
+
+# list registered clusters
+argocd cluster list

solutions/deploy-argocd-apps/setup-ocm.sh

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+#!/bin/bash
+set -e
+
+hub=${CLUSTER1:-hub}
+c1=${CLUSTER1:-cluster1}
+c2=${CLUSTER2:-cluster2}
+
+hubctx="kind-${hub}"
+c1ctx="kind-${c1}"
+c2ctx="kind-${c2}"
+
+kind create cluster --name "${hub}"
+kind create cluster --name "${c1}" --config cluster1-config.yaml
+kind create cluster --name "${c2}" --config cluster2-config.yaml
+
+kubectl config use ${hubctx}
+echo "Initialize the ocm hub cluster"
+joincmd=$(clusteradm init --use-bootstrap-token | grep clusteradm)
+
+kubectl config use ${c1ctx}
+echo "Join cluster1 to hub"
+$(echo ${joincmd} --force-internal-endpoint-lookup --wait | sed "s/<cluster_name>/$c1/g")
+
+kubectl config use ${c2ctx}
+echo "Join cluster2 to hub"
+$(echo ${joincmd} --force-internal-endpoint-lookup --wait | sed "s/<cluster_name>/$c2/g")
+
+kubectl config use ${hubctx}
+echo "Accept join of cluster1 and cluster2"
+clusteradm accept --clusters ${c1},${c2} --wait
+
+kubectl get managedclusters