Updating an application
Now we can use Argo CD and Kustomize to deploy patches to our application manifests using GitOps
For example, lets increase the number of replicas for ui deployment to 3
You can execute commands to add necessary changes to the file apps/deployment.yaml:
~$yq -i '.spec.replicas = 3' ~/environment/argocd/apps/deployment.yaml
Push changes to the Git repository
~$git -C ~/environment/argocd add .
~$git -C ~/environment/argocd commit -am "Update UI service replicas"
~$git -C ~/environment/argocd push
Click Refresh and Sync in ArgoCD UI or use argocd CLI to Sync the application:
~$argocd app sync apps
We should have now 3 pods in ui deployment

To verify, run the following commands:
~$kubectl get deployment -n ui ui
NAME READY UP-TO-DATE AVAILABLE AGE
ui 3/3 3 3 3m33s
~$kubectl get pod -n ui
NAME READY STATUS RESTARTS AGE
ui-6d5bb7b95-hzmgp 1/1 Running 0 61s
ui-6d5bb7b95-j28ww 1/1 Running 0 61s
ui-6d5bb7b95-rjfxd 1/1 Running 0 3m34s