Deploying a Spring Boot App on Kubernetes

-

Overview

In this post, I will be explaining how to deploy a simple Spring Boot Application onto Kubernetes. I will be using MicroK8s for the Kubernetes environment. For a quick guide on how setup MicroK8s refer here.

Spring Boot App Docker Image:

Let us create a simple Spring Boot application and dockerize it. The source could be downloaded from github repo here.
Build the jar file and then dockerize it. I will be using the docker image from local, we can also push/pull this image from a Docker Repository.
Docker command to dockerize the app is:

docker build -t basic-microservice:local .

Run the command 'docker images' and you should be able to see the docker image 'basic-microservice:local'. I have tagged the image as 'local' and not as latest. This is because, since we are using local images for Kubernetes, MicroK8s has a workaround for using local images.

Follow the instructions here, to upload docker image to MicroK8s cache.

Create Deployment in Kubernetes:

Let us create a deployment.yaml file which is an abstraction which specifies how many instances of the app should be there, which docker image to be used etc.


Run the following kubectl command to create the deployment:
microk8s.kubectl  apply -f basic-ms-deployment.yml

 If you observe the deployment yml, we can observe that we have mentioned the docker image name created above and also the 'imagePullPolicy' is set to 'Never', which means the docker image would not be pulled from any repository. We have also configured the 'replicas' to 1, which means only one instance will be created. 

Create Service in Kubernetes:

Let us create a service.yaml file which is an abstraction which specifies how should we access the application deployed in terms of what IP/Port should be used.

Run the following kubectl command to create the service:
microk8s.kubectl  apply -f basic-ms-service.yml
If you observe the service yml, we can observe that it has a selector node with apps tag, which points to 'basic-ms'. This should match the name we gave to our deployment.  We have also provided type as 'NodePort', which means, the application is accessible from outside the cluster using a Node IP and a static port. We have provided the port as 8086, which is the port accessible from outside.

 Run the following commands to observe the Pods/Deployment/Service which are created:
microk8s.kubectl  get pods

 microk8s.kubectl  get deployments

 microk8s.kubectl  get services



Testing the Application:

Finally, let us test our application. When we run 'get services' command, we can see that the port is 31869 which is the port assigned by Kubernetes and 8086 is the port assigned by us.

Let us try to do a curl to our application:
curl 10.152.183.96:8086/hello/message

We can see the REST API providing a response: "From Spring Boot!"

This concludes a very simple application being deployed to Kubernetes with relative ease. Let us look at more features in upcoming posts.


Comments

Post a Comment

Popular posts from this blog

Pivotal Cloud Foundry (PCF) Integration with Elastic Cloud Storage (ECS)

-
Recently, I was involved in integrating Pivotal Cloud Foundry with Elastic Cloud Storage (ECS), an object storage solution from EMC. In this post, I'm going to document the hiccups we faced during this integration and how did we resolve this, so that it is easier for other folks who would like to carry out this integration. References: We followed the blog post, https://blog.codedellemc.com/2016/01/05/emc-ecs-with-cloud-foundry/ and the service broker code from git hub, https://github.com/spiegela/ecs-cf-service-broker .  1. application.yml file Configuration: First task would be to update the application.yml file in the broker code to have the correct configuration. Note the spring profiles created in yml file. The active spring profile is defined in the build.gradle file to be 'development'. So based on that, we need to update the correct section in the yml file. Under the broker section: a) Provide a valid ECS namespace name (The namespa
Read more

Restful code example using Spring MVC

-
In my previous blog, I talked about Restful webservices design. In this blog, I will provide sample code for the same using Spring MVC framework. Spring MVC 3.x supports annotation based controllers, which are Restful in nature.  Let us create a sample Spring web application for performing CRUD on User entity. Creating project: Create a Maven project with a archetype 'maven-archetype-webapp'. pom.xml <!-- version property --> <properties> <spring.version>3.1.2.RELEASE</spring.version> </properties> <!-- servlet dependency for compilation --> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> <type>jar</type> <scope>compile</scope> </dependency> <!-- Spring MVC dependencies --> <dependency> <groupId>org.springframework</groupId> <artifactId&
Read more

Spring Integration - Bulk processing Example

-
Image
In this post, I'm going to share my experience in using Spring Integration for a bulk processing task. This was the first time I was using Spring Integration and it did not disappoint me. It was pretty robust in terms of error handling and definitely scalable. Disclaimer: The actual task being performed has been modified into a fictitious e – commerce domain task, since I cannot reveal the original task which is customer specific and confidential. However, the nature of the task in terms of processing of clob and xml remain the same and the complexity of the original task has been retained. Also, the views posted on this post are strictly personal. Objective: The objective is to work upon customer information from an ecommerce application and process it and save it into database as clob data. The task is to perform data processing by reading xml from a file in the file system and then store it as clob into a table. Following is the high level of tasks required t
Read more