100 Days of DevOps: Day 67

Three-Tier Guestbook Application Deployment on Kubernetes

Executive Summary

I have successfully deployed the required three-tier Guestbook application on the Kubernetes cluster. All six resources—three Deployments and three Services—were created and are now running correctly. The Redis master and slave tiers, along with the PHP frontend, are operational, and the application is exposed externally via the required NodePort 30009.

---

Deployment Execution and Manifest (guestbook-deployment.yaml)

The following unified YAML manifest (guestbook-deployment.yaml) was used to create all application components:

# ----------------------------------------------------
# BACK-END TIER: REDIS MASTER DEPLOYMENT
# ----------------------------------------------------
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-master
  labels:
    app: redis
    role: master
    tier: backend
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
      role: master
  template:
    metadata:
      labels:
        app: redis
        role: master
        tier: backend
    spec:
      containers:
      - name: master-redis-datacenter
        image: redis
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        ports:
        - containerPort: 6379

---
# ----------------------------------------------------
# BACK-END TIER: REDIS MASTER SERVICE
# ----------------------------------------------------
apiVersion: v1
kind: Service
metadata:
  name: redis-master
  labels:
    app: redis
    role: master
    tier: backend
spec:
  ports:
  - port: 6379
    targetPort: 6379
  selector:
    app: redis
    role: master

---
# ----------------------------------------------------
# BACK-END TIER: REDIS SLAVE DEPLOYMENT
# ----------------------------------------------------
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-slave
  labels:
    app: redis
    role: slave
    tier: backend
spec:
  replicas: 2
  selector:
    matchLabels:
      app: redis
      role: slave
  template:
    metadata:
      labels:
        app: redis
        role: slave
        tier: backend
    spec:
      containers:
      - name: slave-redis-datacenter
        image: gcr.io/google_samples/gb-redisslave:v3
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 6379

---
# ----------------------------------------------------
# BACK-END TIER: REDIS SLAVE SERVICE
# ----------------------------------------------------
apiVersion: v1
kind: Service
metadata:
  name: redis-slave
  labels:
    app: redis
    role: slave
    tier: backend
spec:
  ports:
  - port: 6379
    targetPort: 6379
  selector:
    app: redis
    role: slave

---
# ----------------------------------------------------
# FRONT-END TIER DEPLOYMENT
# ----------------------------------------------------
apiVersion: apps/v1
kind: Deployment
metadata:
  name: frontend
  labels:
    app: guestbook
    tier: frontend
spec:
  replicas: 3
  selector:
    matchLabels:
      app: guestbook
      tier: frontend
  template:
    metadata:
      labels:
        app: guestbook
        tier: frontend
    spec:
      containers:
      - name: php-redis-datacenter
        image: gcr.io/google-samples/gb-frontend@sha256:a908df8486ff66f2c4daa0d3d8a2fa09846a1fc8efd65649c0109695c7c5cbff
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
        env:
        - name: GET_HOSTS_FROM
          value: dns
        ports:
        - containerPort: 80

---
# ----------------------------------------------------
# FRONT-END TIER SERVICE (NODEPORT)
# ----------------------------------------------------
apiVersion: v1
kind: Service
metadata:
  name: frontend
  labels:
    app: guestbook
    tier: frontend
spec:
  type: NodePort
  ports:
  - port: 80
    targetPort: 80
    nodePort: 30009
  selector:
    app: guestbook
    tier: frontend

---

Deployment Execution and Verification

The following commands and their outputs confirm the successful creation and status of all components:

Execution Commands

Command	Output
thor@jumphost ~$ kubectl apply -f guestbook-deployment.yaml	deployment.apps/redis-master created service/redis-master created deployment.apps/redis-slave created service/redis-slave created deployment.apps/frontend created service/frontend created

Deployment Health Check

Command	Output
thor@jumphost ~$ kubectl get deployments	NAME READY UP-TO-DATE AVAILABLE AGE frontend 3/3 3 3 50s redis-master 1/1 1 1 51s redis-slave 2/2 2 2 51s

Pod Status Check

Command	Output
thor@jumphost ~$ kubectl get pods	NAME READY STATUS RESTARTS AGE frontend-5dc567d575-9mfnq 1/1 Running 0 50s frontend-5dc567d575-tmq4s 1/1 Running 0 50s frontend-5dc567d575-xfxng 1/1 Running 0 50s redis-master-554f64dc8b-fwbt8 1/1 Running 0 51s redis-slave-bf4ff5dbf-krsb4 1/1 Running 0 51s redis-slave-bf4ff5dbf-r6h2q 1/1 Running 0 50s

Service and Networking Verification

Command	Output
thor@jumphost ~$ kubectl get services	NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE frontend NodePort 10.96.58.65 <none> 80:30009/TCP 40s kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 11m redis-master ClusterIP 10.96.127.189 <none> 6379/TCP 41s redis-slave ClusterIP 10.96.34.8 <none> 6379/TCP 41s

The application is deployed and ready for access on NodePort 30009.