instruction: Explain example: deploying php guestbook application with redis | kubernetes
output: Example: Deploying PHP Guestbook application with Redis
  This tutorial shows you how to build and deploy a simple
  (not production
  ready)
  , multi-tier web application using Kubernetes and
  Docker
  . This example consists of the following
  components:
  A single-instance
  Redis
  to store guestbook entries
  Multiple web frontend instances
  Objectives
  Start up a Redis leader.
  Start up two Redis followers.
  Start up the guestbook frontend.
  Expose and view the Frontend Service.
  Clean up.
  Before you begin
  You need to have a Kubernetes cluster, and the kubectl command-line tool must
  be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a
  cluster, you can create one by using
  minikube
  or you can use one of these Kubernetes playgrounds:
  iximiuz Labs
  Killercoda
  KodeKloud
  Play with Kubernetes
  Your Kubernetes server must be at or later than version v1.14.
  To check the version, enter
  kubectl version
  .
  Start up the Redis Database
  The guestbook application uses Redis to store its data.
  Creating the Redis Deployment
  The manifest file, included below, specifies a Deployment controller that runs a single replica Redis Pod.
  application/guestbook/redis-leader-deployment.yaml
  # SOURCE: https://cloud.google.com/kubernetes-engine/docs/tutorials/guestbook
  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
  Launch a terminal window in the directory you downloaded the manifest files.
  Apply the Redis Deployment from the
  redis-leader-deployment.yaml
  file:
  kubectl apply -f https://k8s.io/examples/application/guestbook/redis-leader-deployment.yaml
  Query the list of Pods to verify that the Redis Pod is running:
  kubectl get pods
  The response should be similar to this:
  NAME READY STATUS RESTARTS AGE
  redis-leader-fb76b4755-xjr2n 1/1 Running 0 13s
  Run the following command to view the logs from the Redis leader Pod:
  kubectl logs -f deployment/redis-leader
  Creating the Redis leader Service
  The guestbook application needs to communicate to the Redis to write its data.
  You need to apply a
  Service
  to
  proxy the traffic to the Redis Pod. A Service defines a policy to access the
  Pods.
  application/guestbook/redis-leader-service.yaml
  # SOURCE: https://cloud.google.com/kubernetes-engine/docs/tutorials/guestbook
  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 Redis Service from the following
  redis-leader-service.yaml
  file:
  kubectl apply -f https://k8s.io/examples/application/guestbook/redis-leader-service.yaml
  Query the list of Services to verify that the Redis Service is running:
  kubectl get service
  The response should be similar to this:
  NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
  kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 1m
  redis-leader ClusterIP 10.103.78.24 <none> 6379/TCP 16s
  Note:
  This manifest file creates a Service named
  redis-leader
  with a set of labels
  that match the labels previously defined, so the Service routes network
  traffic to the Redis Pod.
  Set up Redis followers
  Although the Redis leader is a single Pod, you can make it highly available
  and meet traffic demands by adding a few Redis followers, or replicas.
  application/guestbook/redis-follower-deployment.yaml
  # SOURCE: https://cloud.google.com/kubernetes-engine/docs/tutorials/guestbook
  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
  :
  us-docker.pkg.dev/google-samples/containers/gke/gb-redis-follower:v2
  resources
  :
  requests
  :
  cpu
  :
  100m
  memory
  :
  100Mi
  ports
  :
  -
  containerPort
  :
  6379
  Apply the Redis Deployment from the following
  redis-follower-deployment.yaml
  file:
  kubectl apply -f https://k8s.io/examples/application/guestbook/redis-follower-deployment.yaml
  Verify that the two Redis follower replicas are running by querying the list of Pods:
  kubectl get pods
  The response should be similar to this:
  NAME READY STATUS RESTARTS AGE
  redis-follower-dddfbdcc9-82sfr 1/1 Running 0 37s
  redis-follower-dddfbdcc9-qrt5k 1/1 Running 0 38s
  redis-leader-fb76b4755-xjr2n 1/1 Running 0 11m
  Creating the Redis follower service
  The guestbook application needs to communicate with the Redis followers to
  read data. To make the Redis followers discoverable, you must set up another
  Service
  .
  application/guestbook/redis-follower-service.yaml
  # SOURCE: https://cloud.google.com/kubernetes-engine/docs/tutorials/guestbook
  apiVersion
  :
  v1
  kind
  :
  Service
  metadata
  :
  name
  :
  redis-follower
  labels
  :
  app
  :
  redis
  role
  :
  follower
  tier
  :
  backend
  spec
  :
  ports
  :
  # the port that this service should serve on
  -
  port
  :
  6379
  selector
  :
  app
  :
  redis
  role
  :
  follower
  tier
  :
  backend
  Apply the Redis Service from the following
  redis-follower-service.yaml
  file:
  kubectl apply -f https://k8s.io/examples/application/guestbook/redis-follower-service.yaml
  Query the list of Services to verify that the Redis Service is running:
  kubectl get service
  The response should be similar to this:
  NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
  kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 3d19h
  redis-follower ClusterIP 10.110.162.42 <none> 6379/TCP 9s
  redis-leader ClusterIP 10.103.78.24 <none> 6379/TCP 6m10s
  Note:
  This manifest file creates a Service named
  redis-follower
  with a set of
  labels that match the labels previously defined, so the Service routes network
  traffic to the Redis Pod.
  Set up and Expose the Guestbook Frontend
  Now that you have the Redis storage of your guestbook up and running, start
  the guestbook web servers. Like the Redis followers, the frontend is deployed
  using a Kubernetes Deployment.
  The guestbook app uses a PHP frontend. It is configured to communicate with
  either the Redis follower or leader Services, depending on whether the request
  is a read or a write. The frontend exposes a JSON interface, and serves a
  jQuery-Ajax-based UX.
  Creating the Guestbook Frontend Deployment
  application/guestbook/frontend-deployment.yaml
  # SOURCE: https://cloud.google.com/kubernetes-engine/docs/tutorials/guestbook
  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
  :
  us-docker.pkg.dev/google-samples/containers/gke/gb-frontend:v5
  env
  :
  -
  name
  :
  GET_HOSTS_FROM
  value
  :
  "dns"
  resources
  :
  requests
  :
  cpu
  :
  100m
  memory
  :
  100Mi
  ports
  :
  -
  containerPort
  :
  80
  Apply the frontend Deployment from the
  frontend-deployment.yaml
  file:
  kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-deployment.yaml
  Query the list of Pods to verify that the three frontend replicas are running:
  kubectl get pods -l
  app
  =
  guestbook -l
  tier
  =
  frontend
  The response should be similar to this:
  NAME READY STATUS RESTARTS AGE
  frontend-85595f5bf9-5tqhb 1/1 Running 0 47s
  frontend-85595f5bf9-qbzwm 1/1 Running 0 47s
  frontend-85595f5bf9-zchwc 1/1 Running 0 47s
  Creating the Frontend Service
  The
  Redis
  Services you applied is only accessible within the Kubernetes
  cluster because the default type for a Service is
  ClusterIP
  .
  ClusterIP
  provides a single IP address for the set of Pods the Service is
  pointing to. This IP address is accessible only within the cluster.
  If you want guests to be able to access your guestbook, you must configure the
  frontend Service to be externally visible, so a client can request the Service
  from outside the Kubernetes cluster. However a Kubernetes user can use
  kubectl port-forward
  to access the service even though it uses a
  ClusterIP
  .
  Note:
  Some cloud providers, like Google Compute Engine or Google Kubernetes Engine,
  support external load balancers. If your cloud provider supports load
  balancers and you want to use it, uncomment
  type: LoadBalancer
  .
  application/guestbook/frontend-service.yaml
  # SOURCE: https://cloud.google.com/kubernetes-engine/docs/tutorials/guestbook
  apiVersion
  :
  v1
  kind
  :
  Service
  metadata
  :
  name
  :
  frontend
  labels
  :
  app
  :
  guestbook
  tier
  :
  frontend
  spec
  :
  # if your cluster supports it, uncomment the following to automatically create
  # an external load-balanced IP for the frontend service.
  # type: LoadBalancer
  #type: LoadBalancer
  ports
  :
  # the port that this service should serve on
  -
  port
  :
  80
  selector
  :
  app
  :
  guestbook
  tier
  :
  frontend
  Apply the frontend Service from the
  frontend-service.yaml
  file:
  kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-service.yaml
  Query the list of Services to verify that the frontend Service is running:
  kubectl get services
  The response should be similar to this:
  NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
  frontend ClusterIP 10.97.28.230 <none> 80/TCP 19s
  kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 3d19h
  redis-follower ClusterIP 10.110.162.42 <none> 6379/TCP 5m48s
  redis-leader ClusterIP 10.103.78.24 <none> 6379/TCP 11m
  Viewing the Frontend Service via
  kubectl port-forward
  Run the following command to forward port
  8080
  on your local machine to port
  80
  on the service.
  kubectl port-forward svc/frontend 8080:80
  The response should be similar to this:
  Forwarding from 127.0.0.1:8080 -> 80
  Forwarding from [::1]:8080 -> 80
  load the page
  http://localhost:8080
  in your browser to view your guestbook.
  Viewing the Frontend Service via
  LoadBalancer
  If you deployed the
  frontend-service.yaml
  manifest with type:
  LoadBalancer
  you need to find the IP address to view your Guestbook.
  Run the following command to get the IP address for the frontend Service.
  kubectl get service frontend
  The response should be similar to this:
  NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
  frontend LoadBalancer 10.51.242.136 109.197.92.229 80:32372/TCP 1m
  Copy the external IP address, and load the page in your browser to view your guestbook.
  Note:
  Try adding some guestbook entries by typing in a message, and clicking Submit.
  The message you typed appears in the frontend. This message indicates that
  data is successfully added to Redis through the Services you created earlier.
  Scale the Web Frontend
  You can scale up or down as needed because your servers are defined as a
  Service that uses a Deployment controller.
  Run the following command to scale up the number of frontend Pods:
  kubectl scale deployment frontend --replicas
  =
  5
  Query the list of Pods to verify the number of frontend Pods running:
  kubectl get pods
  The response should look similar to this:
  NAME READY STATUS RESTARTS AGE
  frontend-85595f5bf9-5df5m 1/1 Running 0 83s
  frontend-85595f5bf9-7zmg5 1/1 Running 0 83s
  frontend-85595f5bf9-cpskg 1/1 Running 0 15m
  frontend-85595f5bf9-l2l54 1/1 Running 0 14m
  frontend-85595f5bf9-l9c8z 1/1 Running 0 14m
  redis-follower-dddfbdcc9-82sfr 1/1 Running 0 97m
  redis-follower-dddfbdcc9-qrt5k 1/1 Running 0 97m
  redis-leader-fb76b4755-xjr2n 1/1 Running 0 108m
  Run the following command to scale down the number of frontend Pods:
  kubectl scale deployment frontend --replicas
  =
  2
  Query the list of Pods to verify the number of frontend Pods running:
  kubectl get pods
  The response should look similar to this:
  NAME READY STATUS RESTARTS AGE
  frontend-85595f5bf9-cpskg 1/1 Running 0 16m
  frontend-85595f5bf9-l9c8z 1/1 Running 0 15m
  redis-follower-dddfbdcc9-82sfr 1/1 Running 0 98m
  redis-follower-dddfbdcc9-qrt5k 1/1 Running 0 98m
  redis-leader-fb76b4755-xjr2n 1/1 Running 0 109m
  Cleaning up
  Deleting the Deployments and Services also deletes any running Pods. Use
  labels to delete multiple resources with one command.
  Run the following commands to delete all Pods, Deployments, and Services.
  kubectl delete deployment -l
  app
  =
  redis
  kubectl delete service -l
  app
  =
  redis
  kubectl delete deployment frontend
  kubectl delete service frontend
  The response should look similar to this:
  deployment.apps "redis-follower" deleted
  deployment.apps "redis-leader" deleted
  deployment.apps "frontend" deleted
  service "frontend" deleted
  Query the list of Pods to verify that no Pods are running:
  kubectl get pods
  The response should look similar to this:
  No resources found in default namespace.
  What's next
  Complete the
  Kubernetes Basics
  Interactive Tutorials
  Use Kubernetes to create a blog using
  Persistent Volumes for MySQL and Wordpress
  Read more about
  connecting applications with services
  Read more about
  using labels effectively
  Feedback
  Was this page helpful?
  Yes
  No
  Thanks for the feedback. If you have a specific, answerable question about how to use Kubernetes, ask it on
  Stack Overflow
  .
  Open an issue in the
  GitHub Repository
  if you want to
  report a problem
  or
  suggest an improvement
  .
  Last modified August 24, 2023 at 6:38 PM PST:
  Use code_sample shortcode instead of code shortcode (e8b136c3b3)
  
  ## Kubernetes Deployment Example
  
  ```yaml
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: my-app
    labels:
      app: my-app
  spec:
    replicas: 3
    selector:
      matchLabels:
        app: my-app
    template:
      metadata:
        labels:
          app: my-app
      spec:
        containers:
        - name: my-app
          image: my-app:latest
          ports:
          - containerPort: 8080
          env:
          - name: NODE_ENV
            value: "production"
          resources:
            requests:
              memory: "128Mi"
              cpu: "100m"
            limits:
              memory: "256Mi"
              cpu: "200m"
          livenessProbe:
            httpGet:
              path: /health
              port: 8080
            initialDelaySeconds: 30
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /ready
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 5
  ---
  apiVersion: v1
  kind: Service
  metadata:
    name: my-app-service
  spec:
    selector:
      app: my-app
    ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
    type: ClusterIP
  ```