How to deploy guestbook-app on Kubernetes

This document describe step-by-step how to deploy a guestbook-app on STACKIT Kubernetes Engine.

This deployment is not suitable for production use cases!

Prerequisites

• Create a customer account
• Project is created
• Create a Kubernetes Cluster
• Access a Kubernetes Cluster

Create the Redis database

In this Tutorial, we will use Redis to write and retrieve guestbook entries. To make the Service highly available, we will create a single pod deployment to write the data to the database and create a multiple pod deployment to retrieve the data.

Redis leader deployment

Create the deployment manifest redis-leader-deployment.yaml.

redis-leader-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-leader
  labels:
    app: redis
    role: leader
    tier: backend
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
        role: leader
        tier: backend
    spec:
      containers:
        - name: leader
          image: "docker.io/redis:6.0.5"
          resources:
            requests:
              cpu: 100m
              memory: 100Mi
          ports:
            - containerPort: 6379

Apply the deployment file against your cluster.

kubectl apply -f redis-leader-deployment.yaml

Check your Pods to be sure that the Redis Pod is running.

kubectl get pods

The result should look similar like this:

redis-leader-fb76b4755-fmfq2 1/1 Running 0 79s

Redis Leader Service

The guestbook frontend will have to communicate to the Redis leader through a Service ressource. A Service in Kubernetes is an abstract way to expose an application running on a set of Pods as a network service.

Create the Redis Leader Service manifest.

redis-leader-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: redis-leader
  labels:
    app: redis
    role: leader
    tier: backend
spec:
  ports:
    - port: 6379
      targetPort: 6379
  selector:
    app: redis
    role: leader
    tier: backend

Apply the service file against your cluster.

kubectl apply -f redis-leader-service.yaml

Check the Service to be sure that the Redis Service is running.

kubectl get service

The result should look similar to this:

redis-leader ClusterIP 100.66.106.69 <none> 6379/TCP 5s

Redis follower deployment

To retrieve the data from the Redis Database, we will add Pods to carry the demand.

Create the redis-follower-deployment.yaml.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis-follower
  labels:
    app: redis
    role: follower
    tier: backend
spec:
  replicas: 2
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
        role: follower
        tier: backend
    spec:
      containers:
        - name: follower
          image: registry.ske.eu01.stackit.cloud/test/guestbook-redis-follower:v1
          resources:
            requests:
              cpu: 100m
              memory: 100Mi
          ports:
            - containerPort: 6379

Apply the Deployment file against your cluster.

kubectl apply -f redis-follower-deployment.yaml

Check your Pods to be sure that the Redis Pod is running.

kubectl get pods

The result should look similar like this:

redis-follower-dddfbdcc9-2sc2h 1/1 Running 0 9s
redis-follower-dddfbdcc9-wkrbg 1/1 Running 0 9s
redis-leader-fb76b4755-fmfq2 1/1 Running 0 79s

Redis Follower - Service

The frontend application needs to get data from the Redis Follower. To access the Pods, we will create another Service.

redis-follower-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: redis-follower
  labels:
    app: redis
    role: follower
    tier: backend
spec:
  ports:
    - port: 6379
  selector:
    app: redis
    role: follower
    tier: backend

Apply the service file against your cluster.

kubectl apply -f redis-follower-service.yaml

Check the Service to be sure that the Redis Service is running.

kubectl get service

The result should look similar to this:

redis-follower ClusterIP 100.69.108.108 <none> 6379/TCP 32s
redis-leader ClusterIP 100.66.106.69 <none> 6379/TCP 5s

Create the guestbook frontend

The frontend application will receive guestbook entries and store it into the Redis database. It is configured to talk to either the Redis leader or follower, depending on if the application receives a new guestbook entry or if it should serve existing ones.

Frontend application deployment

Create the frontend-deployment.yaml.

frontend-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: frontend
spec:
  replicas: 3
  selector:
    matchLabels:
      app: guestbook
      tier: frontend
  template:
    metadata:
      labels:
        app: guestbook
        tier: frontend
    spec:
      containers:
        - name: php-redis
          image: registry.ske.eu01.stackit.cloud/test/guestbook-frontend:v1
          env:
            - name: GET_HOSTS_FROM
              value: "dns"
          resources:
            requests:
              cpu: 100m
              memory: 100Mi
          ports:
            - containerPort: 80

Apply the deployment file against your cluster.

kubectl apply -f frontend-deployment.yaml

Check the Pods to be sure that the Frontend Deployment works.

kubectl get pods

The result should look similar to this:

frontend-85595f5bf9-5p4xd 0/1 ContainerCreating 0 25s
frontend-85595f5bf9-n2ftd 0/1 ContainerCreating 0 25s
frontend-85595f5bf9-vnd7d 0/1 ContainerCreating 0 25s

Frontend application service

To access the application from outside the Cluster, we need a service to configure the application externally visible.

Create the frontend-service.yaml.

frontend-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: frontend
  labels:
    app: guestbook
    tier: frontend
spec:
  type: LoadBalancer
  ports:
    - port: 80
  selector:
    app: guestbook
    tier: frontend

Apply the Service file against your cluster.

kubectl apply -f frontend-service.yaml

Check the Service to be sure it works.

kubectl get service

The result should look similar to this:

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
frontend LoadBalancer 100.70.46.37 <pending> 80:31620/TCP 11s
kubernetes ClusterIP 100.64.0.1 <none> 443/TCP 87d
redis-follower ClusterIP 100.69.108.108 <none> 6379/TCP 18h
redis-leader ClusterIP 100.66.106.69 <none> 6379/TCP 18h

Notice that the frontend External-IP is in the state pending. Wait a couple of seconds and check your service again. Now you should get something similar like this:

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
frontend LoadBalancer 100.70.46.37 193.148.175.214 80:31620/TCP 66s

Use the External-IP and paste it into the webbrowser of your choice. You should see something similar to this: