Springboot-Kubernetes-Docker-Goolge Cloud Platform

Springboot-Kubernetes-Docker- Goolge Cloud Platform

Kubernetes is an open source project which can run in many different environments, from laptops to high-availability multi-node clusters, from public clouds to on-premise deployments, from virtual machines to bare metal. We Will deploy a simple Java web-based application (using Spring Boot) to Kubernetes running on Container Engine.

Goal

Goal is to run your web application with as a replicated application running on Kubernetes. You take code that we have developed on our machine, turn it into a Docker container image, and then run that image on Container Engine.

Screenshot:

If you don't already have a Google Account (Gmail or Google Apps), you must create one. Sign-in to Google Cloud Platform console (console.cloud.google.com) and create a new project:

• gcloud auth list

• gcloud config list project

• gcloud config set project <PROJECT_ID>

Use OpenJDK 8

• sudo update-alternatives --config javac

• sudo update-alternatives --config java

Get the Spring Boot Getting Started Example source code

• git clone https://github.com/spring-guides/gs-spring-boot.git

• cd gs-spring-boot/complete

Run the Application Locally

• ./mvnw -DskipTests spring-boot:run

Preview on 8080

Package the Java application as a Docker container

• ./mvnw -DskipTests package

Then, create a Dockerfile:

• touch Dockerfile

Add the following to Dockerfile using your favorite editor

FROM openjdk:8
COPY target/gs-spring-boot-0.1.0.jar /app.jar
EXPOSE 8080/tcp
ENTRYPOINT ["java", "-jar", "/app.jar"] 

Save this Dockerfile and build this image by running this command

• docker build -t gcr.io/PROJECT_ID/hello-java:v1 .

Once this completes (it will take some time to download and extract everything) you can test the image locally with the following command which will run a Docker container as a daemon on port 8080 from your newly-created container image:

• docker run -ti --rm -p 8080:8080 gcr.io/PROJECT_ID/hello-java:v1

Now that the image works as intended you can push it to the Google Container Registry, a private repository for your Docker images accessible from every Google Cloud project (but also from outside Google Cloud Platform) :

• gcloud docker -- push gcr.io/PROJECT_ID/hello-java:v1

Please note that we need to enable the google container registry before moving forward.

Create your clusters

To create cluster use the following command:

gcloud container clusters create hello-java-cluster \
  --num-nodes 2 \
  --machine-type n1-standard-1 \
  --zone us-central1-c 

Deploy your application to Kubernetes

kubectl run hello-java \
  --image=gcr.io/PROJECT_ID/hello-java:v1 \
  --port=8080

To view the deployment you just created, simply run:

• kubectl get deployments

To view the application instances created by the deployment, run this command:

• kubectl get pods

Allow external traffic

• kubectl expose deployment hello-java --type=LoadBalancer

To find the publicly-accessible IP address of the service, simply request kubectl to list all the cluster services:

• kubectl get services

Access the application

• http://<EXTERNAL_IP>:8080

Scale up your service

kubectl scale deployment hello-java --replicas=3

kubectl get deployment

Roll out an upgrade to your service

• Navigate to /gs-spring-boot/complete/src/main/java/hello/HelloController.java
• Introduce some change

Rebuild the application with the latest changes:

• ./mvnw -DskipTests package

Then build a new version of the container image:

• docker build -t gcr.io/PROJECT_ID/hello-java:v2 .

And push the image into the container image registry:

• gcloud docker -- push gcr.io/PROJECT_ID/hello-java:v2

You can use kubectl set image command to ask Kubernetes to deploy the new version of your application across the entire cluster one instance at a time with rolling update:

kubectl set image deployment/hello-java \
hello-java=gcr.io/PROJECT_ID/hello-java:v2 

Roll back

• kubectl rollout undo deployment/hello-java