Deploying an application

We have successfully configured Argo CD on our cluster so now we can deploy an application. To demonstrate the difference between a GitOps-based delivery of an application and other methods, we'll migrate the UI component of the sample application which is currently using the kubectl apply -k approach to the new Argo CD deployment approach.

First let's remove the existing UI component so we can replace it:

~$kubectl delete -k /workspace/manifests/ui --ignore-not-found=true

namespace "ui" deleted

serviceaccount "ui" deleted

configmap "ui" deleted

service "ui" deleted

deployment.apps "ui" deleted

Now, let's get into the cloned Git repository and start creating our GitOps configuration. Copy the existing kustomize configuration for the UI service:

~$cp -R /workspace/manifests/ui ~/environment/argocd/apps

We'll then need to create a kustomization in the apps directory:

/workspace/modules/automation/gitops/argocd/kustomization.yaml

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- ui

Copy this file to the Git repository directory:

~$cp /workspace/modules/automation/gitops/argocd/kustomization.yaml ~/environment/argocd/apps/kustomization.yaml

You Git directory should now look something like this which you can validate by running tree ~/environment/argocd:

.
└── apps
    ├── kustomization.yaml
    └── ui
        ├── configMap.yaml
        ├── deployment.yaml
        ├── kustomization.yaml
        ├── namespace.yaml
        ├── serviceAccount.yaml
        └── service.yaml

2 directories, 7 files

Open the Argo CD UI and navigate to the apps application.

Finally we can push our configuration to the Git repository:

~$git -C ~/environment/argocd add .

~$git -C ~/environment/argocd commit -am "Adding the UI service"

~$git -C ~/environment/argocd push

The default Refresh interval is 3 minutes (180 seconds). You could change the interval by updating the "timeout.reconciliation" value in the argocd-cm config map. If the interval is to 0 then Argo CD will not poll Git repositories automatically and alternative methods such as webhooks and/or manual syncs should be used.

For training purposes, let's set Refresh interval to 5s and restart argocd application controller to deploy our changes faster

~$kubectl patch configmap/argocd-cm -n argocd --type merge \

-p '{"data":{"timeout.reconciliation":"5s"}}'

~$kubectl -n argocd rollout restart deploy argocd-repo-server

~$kubectl -n argocd rollout status deploy/argocd-repo-server

~$kubectl -n argocd rollout restart statefulset argocd-application-controller

~$kubectl -n argocd rollout status statefulset argocd-application-controller

We can also use the Sync button or the argocd CLI to Sync an application:

~$argocd app sync apps --prune

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:

That shows that Argo CD created the basic kustomization, and that it's in sync with the cluster.

We've now successfully migrated the UI component to deploy using Argo CD, and any further changes pushed to the Git repository will be automatically reconciled to our EKS cluster.

You should now have all the resources related to the UI services deployed. To verify, run the following commands:

~$kubectl get deployment -n ui ui

NAME   READY   UP-TO-DATE   AVAILABLE   AGE

ui     1/1     1            1           61s

~$kubectl get pod -n ui

NAME                 READY   STATUS   RESTARTS   AGE

ui-6d5bb7b95-rjfxd   1/1     Running  0          62s