How to create Docker Image and push java app in a Docker Engine

In this blog, I am going to share my knowledge on the creation of a docker image and how can we run in a Docker Engine.

Prerequisite

• Basic Knowledge of Docker
• Docker must be running on your machine.
• Good to aware of Spring boot application.

I already have one spring boot application in my IntelliJ which expose one endpoint /users/{id}. We will see how can we push and run this application in a docker container. 

We need to create one file named Dockerfile to add docker instruction (Check above image).

Now go to Terminal and check whether the docker is running or not on your machine.

Run docker build to create an image and push it to the container using the command.

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

The above command will execute all the operations that we have mentioned in our Dockerfile like pulling OpenJDK 8 from the docker hub if not exist.

Let's see if our image got pushed to docker containers or not by listing all docker images.

docker images

Great! Our image is present in the docker container. Let's run it.

docker run -p 8070:8085 docker-spring-ehcache

Over here, we are telling the Docker to start the application and map docker container port 8085 to our local port 8070. 

Note: Make sure your application has started at 8085 in docker container else it won't be able to map it. Spring boot by default start application on port 8080 so please specify server.port-8050 in application.properties file.

Now go to your browser and hit the endpoint and see if we are getting the response from localhost:8070 or not.

Happy Coding!!!