Run Spring boot application on Docker

In this blog, I will explain how to  run the .jar file on Docker Engine

Docker containers are the fastest growing cloud-enabling technology and driving a new era of computing and application architecture with their lightweight approach to bundle applications and dependencies into isolated, yet highly portable application packages.

What you need?

• Docker running on your computer.

Initial Plan

I will create a simple spring boot application and then create a Dockerfile to build the docker image. finally, I will run the application on Docker container

If you don't have Docker running on your computer. Here is the link to install the Docker 

Step 1: Create Spring-boot application

Navigate this link to create the initial spring-boot application.

Import the project to the Eclipse IDE or whatever you like and create the simple rest endpoint. Here is my code.

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/rest/docker/hello")
public class HelloController {

 @RequestMapping
 public String hello() {
  return "Hello Docker...!";
 }
}

application.properties

server.port=8085

Build the project to create the .jar file. I have the .jar file in the target/docker-jar.jar

Step 2: Create the Dockerfile

I have created the Dockerfile in the project folder

FROM openjdk:8
ADD target/docker-jar.jar docker-jar.jar
EXPOSE 8085
ENTRYPOINT ["java", "-jar", "docker-jar.jar"

Step 3: Build the Docker image and run the application on Docker

Use below command to build the docker image from the Dockerfile

docker build -f Dockerfile -t docker-spring-boot .

Check the docker images using the below command

docker images

output:

REPOSITORY           TAG                 IMAGE ID            CREATED             SIZE
docker-spring-boot   latest              73f02cac7fca        About an hour ago   640MB
<none>               <none>              f410a262a2df        About an hour ago   640MB
openjdk              8                   5f4603da3fbc        12 days ago         624MB
hello-world          latest              fce289e99eb9        4 weeks ago         1.84kB

Okay, Let's run Docker image

docker run -p 8085:8085 docker-spring-boot

Now the spring-boot Application is running on the docker.

check the http://localhost:8085/rest/docker/hello, you will see this output "Hello Docker...!"