ConfigMap and Secret Lab Guide

Difficulty: Beginner Estimated Time: 35 minutes Last Updated: February 11, 2026

Learning Objectives

• Create ConfigMaps and use them in Pods
• Create Secrets and inject them securely
• Compare environment variable and volume mount methods

Prerequisites

• [ ] kubectl, Kubernetes cluster
• [ ] Completed Configuration learning

---

Exercise 1: ConfigMap Creation and Usage

Steps

Step 1.1: Create ConfigMap

# Create from literal values
kubectl create configmap app-config \
  --from-literal=APP_ENV=production \
  --from-literal=LOG_LEVEL=info \
  --from-literal=MAX_CONNECTIONS=100

kubectl get configmap app-config -o yaml

Step 1.2: Create ConfigMap from file

cat > /tmp/app.properties << 'EOF'
database.host=mysql.default.svc.cluster.local
database.port=3306
database.name=myapp
EOF

kubectl create configmap app-properties --from-file=/tmp/app.properties
kubectl describe configmap app-properties

Step 1.3: Inject ConfigMap as environment variables

cat > /tmp/configmap-env-pod.yaml << 'EOF'
apiVersion: v1
kind: Pod
metadata:
  name: config-env-demo
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "echo APP_ENV=$APP_ENV LOG_LEVEL=$LOG_LEVEL; sleep 3600"]
    envFrom:
    - configMapRef:
        name: app-config
EOF

kubectl apply -f /tmp/configmap-env-pod.yaml
kubectl wait --for=condition=ready pod/config-env-demo --timeout=30s
kubectl logs config-env-demo

Expected output:

APP_ENV=production LOG_LEVEL=info

Step 1.4: Mount ConfigMap as volume

cat > /tmp/configmap-vol-pod.yaml << 'EOF'
apiVersion: v1
kind: Pod
metadata:
  name: config-vol-demo
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "cat /config/app.properties; sleep 3600"]
    volumeMounts:
    - name: config-volume
      mountPath: /config
  volumes:
  - name: config-volume
    configMap:
      name: app-properties
EOF

kubectl apply -f /tmp/configmap-vol-pod.yaml
kubectl wait --for=condition=ready pod/config-vol-demo --timeout=30s
kubectl logs config-vol-demo

Need a hint?

• envFrom injects all keys from ConfigMap as environment variables
• When mounting as volume, each key becomes a filename
• Volume-mounted ConfigMaps are automatically updated (environment variables require Pod restart)

---

Exercise 2: Secret Management

Steps

Step 2.1: Create Secret

kubectl create secret generic db-secret \
  --from-literal=DB_USER=admin \
  --from-literal=DB_PASSWORD=s3cr3tP@ss

kubectl get secret db-secret -o yaml

Step 2.2: Inject Secret into Pod

cat > /tmp/secret-pod.yaml << 'EOF'
apiVersion: v1
kind: Pod
metadata:
  name: secret-demo
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "echo User=$DB_USER; echo PassLength=${#DB_PASSWORD}; sleep 3600"]
    env:
    - name: DB_USER
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: DB_USER
    - name: DB_PASSWORD
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: DB_PASSWORD
EOF

kubectl apply -f /tmp/secret-pod.yaml
kubectl wait --for=condition=ready pod/secret-demo --timeout=30s
kubectl logs secret-demo

Expected output:

User=admin
PassLength=10

Step 2.3: Decode Secret

# Check base64 encoded value
kubectl get secret db-secret -o jsonpath='{.data.DB_PASSWORD}' | base64 -d
echo ""

Need a hint?

• Secret values are stored base64 encoded (this is not encryption!)
• In production, use Sealed Secrets, External Secrets, AWS Secrets Manager, etc.
• In kubectl get secret -o yaml, values in the .data field are base64 encoded

---

Exercise 3: Environment Variables vs Volume Mount Comparison

Steps

Step 3.1: Check characteristics of each method

echo "=== Environment Variable Method ==="
kubectl exec config-env-demo -- env | grep -E "APP_ENV|LOG_LEVEL|MAX_CONNECTIONS"

echo ""
echo "=== Volume Mount Method ==="
kubectl exec config-vol-demo -- ls /config/
kubectl exec config-vol-demo -- cat /config/app.properties

---

Cleanup

kubectl delete pod config-env-demo config-vol-demo secret-demo
kubectl delete configmap app-config app-properties
kubectl delete secret db-secret
rm -f /tmp/app.properties /tmp/configmap-env-pod.yaml /tmp/configmap-vol-pod.yaml /tmp/secret-pod.yaml

Next Steps

• Configuration Quiz
• EKS Cluster Creation Lab