docs: Configuration reference and a how-to guide

This commit adds a configuration reference document for the component and a how-to-guide. How-to-guide : GitOps with Azure Arc enabled Lokomotive cluster This How-to guide targets a use case of Deploying configurations using GitOps on an Azure arc enabled Lokomotive cluster. Signed-off-by: Imran Pochi <imran@kinvolk.io>
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diff --git a/docs/configuration-reference/components/azure-arc-onboarding.md b/docs/configuration-reference/components/azure-arc-onboarding.md
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+---
+title: Azure Arc onboarding configuration reference for Lokomotive
+weight: 10
+---
+
+## Introduction
+
+Azure Arc offers simplified management, faster app development, and consistent Azure services.
+
+With Azure Arc, you can:
+
+- Centrally manage a wide range of resources, including
+[Windows](https://azure.microsoft.com/en-in/campaigns/windows-server/) and
+[Linux](https://azure.microsoft.com/en-in/overview/linux-on-azure/) servers, SQL server,
+[Kubernetes](https://azure.microsoft.com/en-in/services/kubernetes-service/) clusters and [Azure
+services](https://azure.microsoft.com/en-in/services/azure-arc/hybrid-data-services/).
+
+- Establish central visibility in the [Azure portal](https://azure.microsoft.com/en-in/features/azure-portal/)
+and enable multi-environment search with Azure Resource Graph.
+
+- Meet [governance](https://azure.microsoft.com/en-in/solutions/governance/) and compliance standards for
+apps, infrastructure and data with [Azure Policy](https://azure.microsoft.com/en-in/services/azure-policy/).
+
+- Delegate access and manage security policies for resources using role-based access control (RBAC) and [Azure
+Lighthouse](https://azure.microsoft.com/en-in/services/azure-lighthouse/).
+
+- Organise and inventory assets through a variety of Azure scopes, such as management groups, subscriptions,
+resource groups and tags.
+
+This component onboards or removes a Lokomotive cluster with Azure Arc.
+
+## Prerequisites
+
+* Microsoft Azure account with permissions to create ResourceGroup and register an application with the
+the Microsoft Identity Platform.
+
+  Detailed instructions and execution steps are mentioned in the
+  [How-to-guide](../../how-to-guides/gitops-using-azure-arc-onboarding-component.md#prerequisites).
+
+## Configuration
+
+Azure Arc onboarding component configuration example:
+
+```tf
+# azure-arc-onboarding.lokocfg
+
+component "azure-arc-onboarding" {
+  application_client_id = "29348jdw-9g23-9kot-21sa-opw129831c2k"
+  application_password  = "foobar"
+  tenant_id             = "s38kjs4k-x123-89h2-7f21-89uffo109921"
+  resource_group        = "azure-arc-lokomotive-resource"
+  cluster_name          = "mercury"
+}
+```
+
+## Attribute reference
+
+Table of all the arguments accepted by the component.
+
+| Argument                | Description                                                                                  | Default  | Type   | Required |
+|-------------------------|----------------------------------------------------------------------------------------------|:--------:|:------:|:--------:|
+| `application_client_id` | Application ID that uniquely identifies your application within the Azure identity platform. | -        | string | true     |
+| `application_password`  | A string value generated that your application can use to identity itself.                   | -        | string | true     |
+| `tenant_id`             | Unique ID of the Azure Active Directory tenant.                                              | -        | string | true     |
+| `resource_group`        | Name or Id of the Azure resource group.                                                      | -        | string | true     |
+| `cluster_name`          | Name of the Lokomotive cluster as provided in the cluster configuration.                     | -        | string | true     |
+
+## Applying
+
+To apply the Azure Arc onboarding component:
+
+```bash
+lokoctl component apply azure-arc-onboarding
+```
+## Deleting
+
+To destroy the component:
+
+```bash
+lokoctl component delete azure-arc-onboarding --delete-namespace
+```
diff --git a/docs/how-to-guides/gitops-using-azure-arc-onboarding-component.md b/docs/how-to-guides/gitops-using-azure-arc-onboarding-component.md
@@ -0,0 +1,271 @@
+---
+title: Deploy configuration using GitOps on an Azure Arc enabled Lokomotive cluster
+weight: 10
+---
+
+## Introduction
+
+Azure Arc offers simplified management, faster app development, and consistent Azure services.
+
+With Azure Arc, you can:
+
+- Centrally manage a wide range of resources, including
+[Windows](https://azure.microsoft.com/en-in/campaigns/windows-server/) and
+[Linux](https://azure.microsoft.com/en-in/overview/linux-on-azure/) servers, SQL server,
+[Kubernetes](https://azure.microsoft.com/en-in/services/kubernetes-service/) clusters and [Azure
+services](https://azure.microsoft.com/en-in/services/azure-arc/hybrid-data-services/).
+
+- Establish central visibility in the [Azure portal](https://azure.microsoft.com/en-in/features/azure-portal/)
+and enable multi-environment search with Azure Resource Graph.
+
+- Meet [governance](https://azure.microsoft.com/en-in/solutions/governance/) and compliance standards for
+apps, infrastructure and data with [Azure Policy](https://azure.microsoft.com/en-in/services/azure-policy/).
+
+- Delegate access and manage security policies for resources using role-based access control (RBAC) and [Azure
+Lighthouse](https://azure.microsoft.com/en-in/services/azure-lighthouse/).
+
+- Organise and inventory assets through a variety of Azure scopes, such as management groups, subscriptions,
+resource groups and tags.
+
+This guide provides the steps for onboarding a Lokomotive cluster on Azure Arc.
+
+## Learning objectives
+
+By the end of this guide, the following things would be accomplished:
+* Onboard a Lokomotive cluster on Azure Arc.
+* Create Azure Arc Kubernetes configuration for the GitOps agent.
+* Watch the GitOps agent deploy Kubernetes resources from the git repository.
+
+## Prerequisites
+
+* A Lokomotive cluster.
+
+* Azure command-line interface `az` installed on the local machine.
+
+* `jq` installed on the system.
+
+* Register providers for Azure Arc enabled Kubernetes:
+   ```bash
+   az provider register --namespace Microsoft.Kubernetes
+   az provider register --namespace Microsoft.KubernetesConfiguration
+   az provider register --namespace Microsoft.ExtendedLocation
+   ```
+
+   Monitor the registration process. Registration may take up to 10 minutes.
+
+   ```bash
+   az provider show -n Microsoft.Kubernetes -o table
+   az provider show -n Microsoft.KubernetesConfiguration -o table
+   az provider show -n Microsoft.ExtendedLocation -o table
+   ```
+
+   **NOTE**: This registration is needed only once per tenant.
+
+* Install `k8s-configuration` extension for Azure CLI.
+
+  ```bash
+  az extension add --name k8s-configuration
+  ```
+
+* Create a resource group:
+
+   ```bash
+   RG_NAME="AzureArcTest"
+   az group create --name "${RG_NAME}" --location EastUS --output table
+   ```
+
+* Create a service principal, its credentials and assign roles to the service principal.
+
+  ```bash
+  # Create a ServicePrincipal and its credentials.
+  SP_NAME=azure-arc-onboarding-service-principal
+  az ad sp create-for-rbac -n "${SP_NAME}" --skip-assignment -o jsonc > /tmp/sp-cred.json
+  SP_ID=$(az ad sp list -o tsv --query='[0].objectId' --display-name "${SP_NAME}")
+
+  # Get Subscription ID.
+  SUB_ID=$(az account show --query id --output tsv)
+
+  # Assign "Kubernetes Cluster - Azure Arc Onboarding" Role by its identifier.
+  az role assignment create --assignee "${SP_ID}" \
+    --role "Kubernetes Cluster - Azure Arc Onboarding" \
+    --scope /subscriptions/${SUB_ID}/resourcegroups/${RG_NAME}
+
+  # Assign "Microsoft.Kubernetes connected cluster" Role by its identifier.
+  az role assignment create --assignee "${SP_ID}" \
+    --role "Microsoft.Kubernetes connected cluster role" \
+    --scope /subscriptions/${SUB_ID}/resourcegroups/${RG_NAME}
+  ```
+
+## Steps
+
+### Step 1: Configure [azure-arc-onboarding](../configuration-reference/components/azure-arc-onboarding.md)
+Lokomotive component.
+
+#### Config
+
+Create a file named `azure-arc-onboarding.lokocfg` with the following contents:
+
+```bash
+
+# Copy values from /tmp/sp-cred.json created in the prerequisites section.
+APPLICATION_ID=$(jq -r .appId /tmp/sp-cred.json)
+APPLICATION_PASSWORD=$(jq -r .password /tmp/sp-cred.json)
+TENANT_ID=$(jq -r .tenant /tmp/sp-cred.json)
+CLUSTER_NAME=mercury
+
+cat > azure-arc-onboarding.lokocfg <<EOF
+component "azure-arc-onboarding" {
+  application_client_id = "${APPLICATION_ID}"
+  application_password  = "${APPLICATION_PASSWORD}"
+  tenant_id             = "${TENANT_ID}"
+  resource_group        = "${RG_NAME}"
+  cluster_name          = "${CLUSTER_NAME}"
+}
+EOF
+```
+
+Ensure that none of the fields is empty.
+
+Check out the component's [configuration
+reference](../configuration-reference/components/azure-arc-onboarding.md) for more information.
+
+#### Deploy the component
+
+Execute the following command to deploy the `azure-arc-onboarding` component:
+
+```bash
+lokoctl component apply azure-arc-onboarding
+```
+
+Verify the pod in the `azure-arc-onboarding` namespace is in the `Completed` state (this may take a few minutes):
+
+```bash
+$ kubectl -n azure-arc-onboarding get pods -n azure-arc-onboarding
+NAME                       READY   STATUS      RESTARTS   AGE
+azure-arc-register-4s54j   0/1     Completed   0          81m
+```
+
+Azure Arc installs various Helm charts in the `azure-arc` namespace, verify that all the deployments are in
+`Running` state:
+
+```bash
+$ kubectl -n azure-arc get pods
+NAME                                         READY   STATUS    RESTARTS   AGE
+cluster-metadata-operator-7cff574c4f-ld8cv   2/2     Running   0          83m
+clusterconnect-agent-6dfd867c68-629xg        3/3     Running   0          83m
+clusteridentityoperator-fd498bf96-dqlhr      2/2     Running   0          83m
+config-agent-bd647558d-f46xn                 2/2     Running   0          83m
+controller-manager-8676dcdc6-mv68p           2/2     Running   0          83m
+extension-manager-bcfd5b597-lsk85            2/2     Running   0          83m
+flux-logs-agent-6596f58c56-55l7r             1/1     Running   0          83m
+kube-aad-proxy-97bf4bcf8-g9djl               2/2     Running   0          83m
+metrics-agent-5b9b94754f-qf5q2               2/2     Running   0          83m
+resource-sync-agent-f8c7c6b6b-zvhx4          2/2     Running   0          83m
+```
+
+### Step 3: Create a Kubernetes configuration
+
+#### Create a configuration
+
+Once the Lokomotive cluster is onboarded on Azure Arc, we can proceed ahead with creating a configuration for
+deploying the GitOps agent.
+
+```bash
+az k8s-configuration create \
+  --name cluster-config \
+  --cluster-name "${CLUSTER_NAME}" \
+  --resource-group "${RG_NAME}" \
+  --operator-instance-name cluster-config \
+  --operator-namespace cluster-config \
+  --repository-url https://github.com/ipochi/azure-arc-nginx-demo \
+  --scope cluster \
+  --cluster-type connectedClusters \
+  --operator-params='--git-branch=main'
+```
+
+- `name` - the name of the Kubernetes configuration you want.
+- `cluster-name` - the name of the cluster provided in `azure-arc-onboarding` component configuration.
+- `resource-group` - Azure Resource group name provided in the `azure-arc-onboarding` component configuration.
+- `operator-instance-name` - the name of the Operator instance.
+- `repository-url` - the name of the git repository.
+- `scope` - scope of the operator. Accepted values: `cluster` or `namespace`.
+- `cluster-type` - Arc cluster type. Accepted values: `connectedClusters` or `managedClusters`.
+   **NOTE**: If the Lokomotive cluster is deployed on AKS, then the value of `cluster-type` is `managedClusters`
+- `operator-params` - Additional parameters to pass to the Operator. By default, the GitOps agent tracks and
+   syncs with the `master` branch. In this case, we are changing default the branch to `main`.
+
+This command creates two Deployments in the provided namespace `cluster-config`, corresponding to the GitOps
+agent that Azure Arc uses:
+
+```bash
+$ kubectl get deployments -n cluster-config
+NAME                         READY   UP-TO-DATE   AVAILABLE   AGE
+cluster-config               1/1     1            1           103m
+memcached-cluster-config     1/1     1            1           103m
+
+kubectl get pods -n cluster-config
+NAME                                          READY   STATUS    RESTARTS   AGE
+cluster-config-5f68dd9bd5-xsmc9               1/1     Running   0          5d18h
+memcached-cluster-config-857d47969f-v2g8q     1/1     Running   0          5d18h
+```
+
+Once the `cluster-config` pods are in `Running` state, you'll notice the new resources created by the GitOps
+agent in the namespace `demo`. The manifests for these resources are pulled from the provided git repository.
+
+```bash
+kubectl get all -n demo
+NAME                           READY   STATUS    RESTARTS   AGE
+pod/my-nginx-5bcdc5784-fb87k   1/1     Running   0          105m
+pod/my-nginx-5bcdc5784-g2gt2   1/1     Running   0          105m
+
+NAME               TYPE       CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
+service/my-nginx   NodePort   10.3.250.153   <none>        8080:32500/TCP   105m
+
+NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
+deployment.apps/my-nginx   2/2     2            2           105m
+
+NAME                                  DESIRED   CURRENT   READY   AGE
+replicaset.apps/my-nginx-5bcdc5784    2         2         2       105m
+replicaset.apps/my-nginx-5f4dfbff8c   0         0         0       105m
+```
+
+If you used your git repository URL, try pushing some changes to your repository. You'll notice the changes
+propagate instantly without the need for any manual intervention.
+
+## Cleanup
+
+Before removing the Lokomotive cluster from Azure arc, it is good practice to remove the GitOps agent.
+
+```bash
+az k8s-configuration delete \
+  --name cluster-config \
+  --cluster-name "${CLUSTER_NAME}" \
+  --resource-group "${RG_NAME}" \
+  --cluster-type connectedclusters \
+```
+
+Next, we remove the Lokomotive cluster from Azure Arc, by deleting the component:
+
+```bash
+lokoctl component delete azure-arc-onboarding
+```
+
+Finally, if the Lokomotive cluster is not needed, destroy the cluster:
+
+```bash
+lokoctl cluster destroy --confirm
+```
+
+**NOTE**: Store Service principal credentials somewhere safe and delete the temporary credentials file:
+
+```bash
+rm -rf /tmp/sp-cred.json
+```
+
+## Additional resources
+
+- `azure-arc-onboarding` component [configuration reference](../configuration-reference/components/azure-arc-onboarding.md) guide.
+- Azure Arc docs:
+
+  - [Configurations and GitOps with Azure Arc enabled clusters](https://docs.microsoft.com/en-us/azure/azure-arc/kubernetes/conceptual-configurations).
+  - [Using Azure Policy to apply GitOps configurations at scale](https://docs.microsoft.com/en-us/azure/azure-arc/kubernetes/use-azure-policy).