Simple Java + Docker

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1. Introduction

As a Java developer I want to build a lean Docker image for my java app. A Docker feature named "multi-stage builds" make this process so easy and straight forward.

2. Sample Project

As a simple sample project we have a Spring-Boot hello world project which responses on http://localhost:8080 You can provide your desired project or clone/download the github repository from here:
https://github.com/AmirKeshavarz/hello-docker-java

3. Dockerfile

In the root of the project there would be a file named Dockerfile containing below listing:

4. How to run

1. Docker must be installed on your system
2. In terminal go to root of the project and run below command for building docker image:
bash

sudo docker build -t hello .

1	sudo docker build -t hello .

* Please notice that there is a dot(.) at the end of above command.

3. In terminal run below commands for running the container:
bash

sudo docker run -dit hello -p 8080:8080

1	sudo docker run -dit hello -p 8080:8080

4. Check your application in browser: Go to browser and browse into http:\\localhost:8080
5. Check your docker container: Go to terminal and run below command:
bash

sudo docker ps --- output --- CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES b0c3ecbeafc0 amir/hello "java -jar hellojava…" 15 seconds ago Up 10 seconds 0.0.0.0:8080->8080/tcp intelligent_vaughan

1 2 3 4 5

sudo docker ps   --- output --- CONTAINER ID        IMAGE                          COMMAND                  CREATED             STATUS              PORTS                                            NAMES b0c3ecbeafc0        amir/hello                     "java -jar hellojava…"   15 seconds ago      Up 10 seconds       0.0.0.0:8080->8080/tcp                           intelligent_vaughan

5. Next

Below, a couple of points are mentioned which are not described here to keep this article simple.

• Use -v option of docker for mounting your local maven repository and prevent downloading maven dependencies in build repetitive phase.
• Use Maven plugins for building images instead of direct docker CLI commands.
• Push docker image into a docker hub to make it accessible from hosts outer of your local.