Task 3 - Managing Application Initialization

Task Objective

Create a deployment named:

lab153deploy

Requirements:

Run the nginx image.
Wait 30 seconds before starting nginx.
Use an initContainer to perform the delay.

💡 Exam Tip: If a question asks to delay application startup, the expected answer is usually an initContainer.

Step 1 - Create Deployment YAML

apiVersion: apps/v1
kind: Deployment
metadata:
  name: lab153deploy

spec:
  replicas: 1

  selector:
    matchLabels:
      app: lab153deploy

  template:
    metadata:
      labels:
        app: lab153deploy

    spec:

      initContainers:
      - name: wait-30-seconds
        image: busybox
        command:
        - sh
        - -c
        - sleep 30

      containers:
      - name: nginx
        image: nginx

Step 2 - Apply the Deployment

kubectl apply -f lab153deploy.yaml

Step 3 - Verify Pod Initialization

kubectl get pods

During startup you should see:

NAME                         READY   STATUS
lab153deploy-xxxxx           0/1     Init:0/1

After approximately 30 seconds:

NAME                         READY   STATUS
lab153deploy-xxxxx           1/1     Running

Step 4 - Verify the Init Container

kubectl describe pod

Look for:

Init Containers:
  wait-30-seconds:
    State: Completed

This confirms the initialization completed before nginx was started.

Fast Exam Method

kubectl create deployment lab153deploy \
--image=nginx \
--dry-run=client -o yaml > lab153deploy.yaml

Edit the YAML and insert the initContainer section.

📝 Memory Hook:

Init Container = "Do this first."
Main Container = "Start only after init completes."

Sleep 30 → nginx starts 30 seconds later.