Practicing the ApplicationSet

You've deployed todo-app to a single namespace from two sources.

Here is what we did previously (we're going to use this as a starting point):

cat < $HOME/todo/app/manifests/app-multi-source.yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: todo-app
  namespace: argocd
spec:
  destination:
    namespace: default
    server: https://kubernetes.default.svc
  project: default
  sources:
    - repoURL: $GITLAB_URL
      targetRevision: main
      ref: valsrc
    - chart: todo
      repoURL: $HELM_REPO_URL
      targetRevision: 0.2.0
      helm:
        valueFiles:
          - $valsrc/manifests/values-override.yaml
  syncPolicy:
    automated:
      prune: true
      selfHeal: true
      allowEmpty: true
EOF

Now here's what we want to do: convert this into an ApplicationSet that deploys the same app to two namespaces on the same cluster, dev and prod, with different configuration per environment.

Produce 2 Applications from 1 ApplicationSet, with 1 Application per environment.

Field	`todo-dev`	`todo-prod`
Namespace	`dev`	`prod`
replicaCount	1	3
Values file	`values-dev.yaml`	`values-prod.yaml`

We will keep everything else the same as before: the destination cluster, the todo chart from $HELM_REPO_URL at 0.2.0, the values file loaded from Git through a ref source, auto-created namespaces, and automated sync with prune and self-heal.

You're done when these verifications pass:

# 2 Applications, generated from one file
kubectl get applications -n argocd
# Expect: todo-dev and todo-prod, both Synced/Healthy

# The per-namespace replica counts actually differ
kubectl get deploy -n dev todo -o jsonpath='{.spec.replicas}'    # 1
kubectl get deploy -n prod todo -o jsonpath='{.spec.replicas}'   # 3

Here's the solution.

First, create and commit the two values files. The starting point used a single values-override.yaml; the exercise needs one per environment, differing only in replicaCount.

cat < $HOME/todo/app/manifests/values-dev.yaml
replicaCount: 1
EOF

cat < $HOME/todo/app/manifests/values-prod.yaml
replicaCount: 3
EOF

Commit and push them, since the ref source reads from Git, not your local disk:

cd $HOME/todo/app && \
  git add manifests/values-dev.yaml manifests/values-prod.yaml && \
  git commit -m "Add per-environment values files for dev and prod" && \

GitOps the Hard Way, with Argo CD

Build Real GitOps Pipelines From Empty Clusters to Automated Deploys

Enroll now to unlock all content and receive all future updates for free.

Unlock now $20.99 Learn More

Previous Next