Part-90: 🚀 Kubernetes Deployment with Declarative Way in Google Kubernetes Engine (GCP)

#kubernetes #devops #learning #cloud

In our previous guides, we created Deployments using the imperative way.
Now, let’s switch gears and explore the declarative approach using YAML manifests.

This is the production-grade approach, as it ensures configurations are version-controlled, reusable, and consistent.

📌 Step 01: Copy Templates from ReplicaSet

We’ll start by deleting any existing deployments/services, then create a fresh Deployment and Service using YAML definitions.

🔹 Delete Existing Deployment and Service

kubectl get deployments
kubectl delete deployment my-first-deployment

kubectl get svc
kubectl delete svc my-first-deployment-service

🔹 Create a Deployment Manifest

We’ll create a Deployment definition by modifying our earlier ReplicaSet template.
Changes made:

kind: Deployment instead of ReplicaSet
Image version updated to 3.0.0
All labels/selectors updated to myapp3

📄 01-deployment-definition.yml

apiVersion: apps/v1
kind: Deployment  
metadata:
  name: myapp3-deployment
spec:
  replicas: 3
  selector: 
    matchLabels: 
      app: myapp3
  template:
    metadata:
      name: myapp3-pod
      labels:
        app: myapp3
    spec:
      containers:
        - name: myapp3-container
          image: ghcr.io/stacksimplify/kubenginx:3.0.0
          ports: 
            - containerPort: 80

🔹 Apply Deployment

# Change Directory
cd kube-manifests

# Apply Deployment
kubectl apply -f 01-deployment-definition.yml

# Verify Deployment
kubectl get deploy
kubectl get rs
kubectl get po

🔹 Create a LoadBalancer Service

Now let’s expose our Deployment externally using a LoadBalancer Service.

📄 02-deployment-LoadBalancer-service.yml

apiVersion: v1
kind: Service 
metadata:
  name: deployment-loadbalancer-service
spec:
  type: LoadBalancer
  selector:
    app: myapp3
  ports: 
    - name: http
      port: 80       # Service Port
      targetPort: 80 # Container Port

🔹 Apply Service

kubectl apply -f 02-deployment-LoadBalancer-service.yml

# List Services
kubectl get svc

# Get Public IP (assigned by GCP LoadBalancer)
kubectl get nodes -o wide

# Access Application
http://<Load-Balancer-Service-IP>

✅ Now you should see Application Version: 3.0.0 served through your GCP LoadBalancer.

📌 Step 02: Clean-Up Kubernetes Deployment and Service

Once done testing, let’s clean up the resources.

# Delete Deployment
kubectl delete -f 01-deployment-definition.yml

# Delete LoadBalancer Service
kubectl delete -f 02-deployment-LoadBalancer-service.yml