Use Gitops delivery with Argo CD

This topic explains how you can deliver Carvel Packages, created by the Carvel Package Supply Chains, from a GitOps repository to one or more run clusters using Argo CD for Supply Chain Choreographer.

Prerequisites

To use Gitops Delivery with Argo CD, you must complete the following prerequisites:

Create a Workload that uses a Carvel Package Supply Chain. You must have at least one Carvel Package generated by this Workload stored in your GitOps repository. See Carvel Package Supply Chains.
Have at least one run cluster. Run clusters serve as your deployment environments. They can either be Tanzu Application Platform clusters, or Kubernetes clusters, but they must have kapp-controller and Contour installed. See the Carvel documentation and the Contour documentation.
Create a build cluster that has network access to your run clusters to use a build cluster to control the deployment on all the run clusters. You must also install Argo CD. If you intend to deploy directly on the run cluster without a build cluster, a build cluster is only necessary for building the package.

Set up run cluster namespaces

Each run cluster must have a namespace and ServiceAccount with the correct permissions to deploy the Carvel Packages.

If your run cluster is a Tanzu Application Platform cluster, see Set up developer namespaces to use installed packages.

If your run cluster is not a Tanzu Application Platform cluster, create a namespace and ServiceAccount with the following permissions:

---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: <run-cluster-ns>
  name: app-cr-role
rules:
- apiGroups: ["apps"]
  resources: ["deployments"]
  verbs: ["get", "list", "create", "update", "delete"]
- apiGroups: [""]
  resources: ["configmaps", "services"]
  verbs: ["get", "list", "create", "update", "delete"]
- apiGroups: ["networking.k8s.io"]
  resources: ["ingresses"]
  verbs: ["get", "list", "create", "update", "delete"]

Create Carvel PackageInstalls and secrets

For each Carvel Package and run cluster, you must create a Carvel PackageInstall and a Secret. The Carvel PackageInstall and the Secret are stored in your GitOps repository and deployed to run clusters by Flux CD.

The following example shows a GitOps repository structure after completing this section:

app.default.tap/
  packages/
    20230321004057.0.0.yaml  # Package
  staging/
    packageinstall.yaml      # PackageInstall
    params.yaml              # Secret
  prod/
    packageinstall.yaml      # PackageInstall
    params.yaml              # Secret

For each run cluster:

Create a Secret that has the values for each Package parameter. You can view the configurable properties of the Package by inspecting the Package CR’s valuesSchema, or in the Carvel Package Supply Chains documentation. Store the Secret in your GitOps repository at <package_name>/<run_cluster>/params.yaml.

Note
You can skip this step to use the default parameter values.
```
---
apiVersion: v1
kind: Secret
metadata:
  name: app-values
stringData:
  values.yaml: |
    ---
    workload_name: app
    replicas: 2
    hostname: app.mycompany.com
```

Create a PackageInstall. Reference the Secret you created earlier. Store the PackageInstall in your GitOps repository at <package_name>/<run_cluster>/packageinstall.yaml.

Note
If you skipped creation of the Secret, omit the values key.

---
apiVersion: packaging.carvel.dev/v1alpha1
kind: PackageInstall
metadata:
  name: app
spec:
  serviceAccountName: <run-cluster-ns-sa> # ServiceAccount on run cluster with permissions to deploy Package, see "Set up run Cluster Namespaces"
  packageRef:
    refName: app.default.tap # name of the Package
    versionSelection:
      constraints: 20230321004057.0.0 # version of the Package
  values:
  - secretRef:
      name: app-values # Secret created in previous step

Note
To continuously deploy the latest version of your Package, you can set versionSelection.constraints: >=0.0.0

Push the PackageInstalls and Secrets to your GitOps repository.

Create an Argo CD application on the Build cluster

Configure Argo CD on the Build cluster to deploy your Packages, PackageInstalls, and Secrets to each run cluster.

Note
You start by registering a cluster’s credentials to Argo CD. This is only necessary when deploying to an external cluster.

First list all clusters contexts in your current kubeconfig:
```
kubectl config get-contexts -o name
```
Choose a context name from the list and supply it to the argocd cluster. This command installs a ServiceAccount, argocd-manager, into the kube-system namespace of that kubectl context, binding the service account to an admin-level ClusterRole. Argo CD uses this service account token to perform its management tasks, such as deployment and monitoring.

For example, for run-cluster1 context, run:
```
argocd cluster add run-cluster-1
```
Note
You can modify the rules of the argocd-manager-role role so that it only has create, update, patch, delete privileges to a limited set of namespaces, groups, kinds. However get, list, and watch privileges are required at the cluster-scope.

Set the current namespace to argocd:

kubectl config set-context --current --namespace=argocd

Create hello-world-app:

argocd app create hello-world-app --repo https://github.com/mycompany/gitops-repo

After you create the application, you can view its status by running:

argocd app get hello-world-app

The output is similar to the following:

Name:               hello-world-app
Server:             https://kubernetes.default.svc
Namespace:          default
URL:                https://10.97.164.88/applications/hello-world-app
Repo:               https://github.com/mycompany/gitops-repo.git
Target:
Path:               hello-world-app
Sync Policy:        <none>
Sync Status:        OutOfSync from  (1ff8a67)
Health Status:      Missing

GROUP  KIND        NAMESPACE  NAME                 STATUS     HEALTH
apps   Deployment  default    hello-world-app-dep  OutOfSync  Missing
      Service     default    hello-world-app-svc  OutOfSync  Missing

This command retrieves the manifests from the repository and performs a kubectl apply. The hello-world-app app is running and you can now view its resource components, logs, events, and health status.

The application status is initially in OutOfSync state since the application has yet to be deployed, and no Kubernetes resources have been created. To sync (deploy) the application, run:
```
argocd app sync hello-world-app
```

Verify installation

To verify your installation:

On your Build cluster, confirm that your Flux CD GitRepository and Kustomizations are reconciling by running:
```
kubectl get gitrepositories,kustomizations -A
```
Target a run cluster. Confirm that all Packages from the GitOps repository are deployed by running:
```
kubectl get packages -A
```
Target a run cluster. Confirm that all PackageInstalls are reconciled by running:
```
kubectl get packageinstalls -A
```

Now you can access your application on each run cluster.