Deploying an application

Argo CD applies the GitOps methodology to Kubernetes. It uses Git as a source of truth for your cluster's desired state. You can use Argo CD to deploy applications, monitor their health, and sync them with the desired state. Kubernetes manifests can be specified in several ways:

• Kustomize applications
• Helm charts
• Jsonnet files
• Plain directories of Kubernetes YAML files

In this lab exercise, we'll deploy a simple applications specified in Kustomize using Argo CD. We'll use the catalog application from our EKS Workshop repository.

Create an Argo CD Application

Argo CD application is a CRD Kubernetes resource object representing a deployed application instance in an environment. It defines key information about the application, such as the application name, the Git repository, and the path to the Kubernetes manifests. The application resource also defines the desired state of the application, such as the target revision, the sync policy, and the health check policy.

Let's create a namespace for our application:

~$kubectl create ns argocd-demo

Create an Argo CD application:

~$argocd app create argocd-demo --repo https://github.com/aws-samples/eks-workshop-v2.git --path environment/workspace/modules/automation/gitops/argocd --dest-server https://kubernetes.default.svc --dest-namespace argocd-demo

 application 'argocd-demo' created

Verify that the application has been created:

~$argocd app list

NAME                CLUSTER                         NAMESPACE    PROJECT  STATUS     HEALTH   SYNCPOLICY  CONDITIONS  REPO                                                PATH                                                    TARGET

argocd/argocd-demo  https://kubernetes.default.svc  argocd-demo  default  OutOfSync  Healthy  <none>      <none>      https://github.com/aws-samples/eks-workshop-v2.git  environment/workspace/modules/automation/gitops/argocd

Alternatively, you can also intereact with Argo CD objects in the cluster using the kubectl command:

~$kubectl get apps -n argocd

NAME          SYNC STATUS   HEALTH STATUS

argocd-demo   OutOfSync     Missing

Open the Argo CD UI and navigate to the argocd-demo application. You should see the following screen:

Notice that the application is currently in OutOfSync state. This means that the application is not deployed and in sync with the desired state.

Let's check if there are any pods running in the argocd-demo namespace:

~$kubectl get pods -n argocd-demo

No resources found in argocd-demo namespace.

Now, we're going to sync the application. This will deploy the application to the cluster and bring it to the desired state.

Click on the SYNC button in the UI of the app.

Or, you can also use the argocd CLI:

~$argocd app sync argocd-demo

After a short period of time, the application should be in Synced state and the resources should be deployed, the UI should look like this:

Let's check if resources have been deployed:

~$kubectl get all -n argocd-demo

NAME                           READY   STATUS    RESTARTS        AGE

pod/catalog-6898c9f5d6-dzbl9   1/1     Running   2 (4m37s ago)   4m40s

pod/catalog-mysql-0            1/1     Running   0               4m40s

NAME                    TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE

service/catalog         ClusterIP   172.20.127.102   <none>        80/TCP     4m40s

service/catalog-mysql   ClusterIP   172.20.197.206   <none>        3306/TCP   4m40s

NAME                      READY   UP-TO-DATE   AVAILABLE   AGE

deployment.apps/catalog   1/1     1            1           4m41s

NAME                                 DESIRED   CURRENT   READY   AGE

replicaset.apps/catalog-6898c9f5d6   1         1         1       4m41s

NAME                             READY   AGE

statefulset.apps/catalog-mysql   1/1     4m41s

You've succefully deployed an application using Argo CD with the GitOps model.