---
title: "Example: Deploying PHP Guestbook application with Redis"
reviewers:
- ahmetb
- jimangel
content_type: tutorial
weight: 20
card:
name: tutorials
weight: 30
title: "Stateless Example: PHP Guestbook with Redis"
min-kubernetes-server-version: v1.14
source: https://cloud.google.com/kubernetes-engine/docs/tutorials/guestbook
---
<!-- overview -->
This tutorial shows you how to build and deploy a simple _(not production
ready)_, multi-tier web application using Kubernetes and
[Docker](https://www.docker.com/). This example consists of the following
components:
* A single-instance [Redis](https://www.redis.io/) to store guestbook entries
* Multiple web frontend instances
## {{% heading "objectives" %}}
* Start up a Redis leader.
* Start up two Redis followers.
* Start up the guestbook frontend.
* Expose and view the Frontend Service.
* Clean up.
## {{% heading "prerequisites" %}}
{{< include "task-tutorial-prereqs.md" >}}
{{< version-check >}}
<!-- lessoncontent -->
## 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.
{{% code_sample file="application/guestbook/redis-leader-deployment.yaml" %}}
1. Launch a terminal window in the directory you downloaded the manifest files.
1. Apply the Redis Deployment from the `redis-leader-deployment.yaml` file:
<!---
for local testing of the content via relative file path
kubectl apply -f ./content/en/examples/application/guestbook/redis-leader-deployment.yaml
-->
```shell
kubectl apply -f https://k8s.io/examples/application/guestbook/redis-leader-deployment.yaml
```
1. Query the list of Pods to verify that the Redis Pod is running:
```shell
kubectl get pods
```
The response should be similar to this:
```
NAME READY STATUS RESTARTS AGE
redis-leader-fb76b4755-xjr2n 1/1 Running 0 13s
```
1. Run the following command to view the logs from the Redis leader Pod:
```shell
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](/docs/concepts/services-networking/service/) to
proxy the traffic to the Redis Pod. A Service defines a policy to access the
Pods.
{{% code_sample file="application/guestbook/redis-leader-service.yaml" %}}
1. Apply the Redis Service from the following `redis-leader-service.yaml` file:
<!---
for local testing of the content via relative file path
kubectl apply -f ./content/en/examples/application/guestbook/redis-leader-service.yaml
-->
```shell
kubectl apply -f https://k8s.io/examples/application/guestbook/redis-leader-service.yaml
```
1. Query the list of Services to verify that the Redis Service is running:
```shell
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.
{{< /note >}}
### 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.
{{% code_sample file="application/guestbook/redis-follower-deployment.yaml" %}}
1. Apply the Redis Deployment from the following `redis-follower-deployment.yaml` file:
<!---
for local testing of the content via relative file path
kubectl apply -f ./content/en/examples/application/guestbook/redis-follower-deployment.yaml
-->
```shell
kubectl apply -f https://k8s.io/examples/application/guestbook/redis-follower-deployment.yaml
```
1. Verify that the two Redis follower replicas are running by querying the list of Pods:
```shell
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](/docs/concepts/services-networking/service/).
{{% code_sample file="application/guestbook/redis-follower-service.yaml" %}}
1. Apply the Redis Service from the following `redis-follower-service.yaml` file:
<!---
for local testing of the content via relative file path
kubectl apply -f ./content/en/examples/application/guestbook/redis-follower-service.yaml
-->
```shell
kubectl apply -f https://k8s.io/examples/application/guestbook/redis-follower-service.yaml
```
1. Query the list of Services to verify that the Redis Service is running:
```shell
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.
{{< /note >}}
## 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
{{% code_sample file="application/guestbook/frontend-deployment.yaml" %}}
1. Apply the frontend Deployment from the `frontend-deployment.yaml` file:
<!---
for local testing of the content via relative file path
kubectl apply -f ./content/en/examples/application/guestbook/frontend-deployment.yaml
-->
```shell
kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-deployment.yaml
```
1. Query the list of Pods to verify that the three frontend replicas are running:
```shell
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](/docs/concepts/services-networking/service/#publishing-services-service-types).
`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`.
{{< /note >}}
{{% code_sample file="application/guestbook/frontend-service.yaml" %}}
1. Apply the frontend Service from the `frontend-service.yaml` file:
<!---
for local testing of the content via relative file path
kubectl apply -f ./content/en/examples/application/guestbook/frontend-service.yaml
-->
```shell
kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-service.yaml
```
1. Query the list of Services to verify that the frontend Service is running:
```shell
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`
1. Run the following command to forward port `8080` on your local machine to port `80` on the service.
```shell
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
```
1. load the page [http://localhost:8080](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.
1. Run the following command to get the IP address for the frontend Service.
```shell
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
```
1. 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.
{{< /note >}}
## 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.
1. Run the following command to scale up the number of frontend Pods:
```shell
kubectl scale deployment frontend --replicas=5
```
1. Query the list of Pods to verify the number of frontend Pods running:
```shell
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
```
1. Run the following command to scale down the number of frontend Pods:
```shell
kubectl scale deployment frontend --replicas=2
```
1. Query the list of Pods to verify the number of frontend Pods running:
```shell
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
```
## {{% heading "cleanup" %}}
Deleting the Deployments and Services also deletes any running Pods. Use
labels to delete multiple resources with one command.
1. Run the following commands to delete all Pods, Deployments, and Services.
```shell
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
```
1. Query the list of Pods to verify that no Pods are running:
```shell
kubectl get pods
```
The response should look similar to this:
```
No resources found in default namespace.
```
## {{% heading "whatsnext" %}}
* Complete the [Kubernetes Basics](/docs/tutorials/kubernetes-basics/) Interactive Tutorials
* Use Kubernetes to create a blog using [Persistent Volumes for MySQL and Wordpress](/docs/tutorials/stateful-application/mysql-wordpress-persistent-volume/#visit-your-new-wordpress-blog)
* Read more about [connecting applications with services](/docs/tutorials/services/connect-applications-service/)
* Read more about [using labels effectively](/docs/concepts/overview/working-with-objects/labels/#using-labels-effectively)