Deploying a Java Spring Server with a Docker Container

In this guide, I'll show you how to deploy a Java Spring server using Docker. Below are the steps to follow:

1. Launch an Ubuntu Server

For this demo, let's assume you have launched a server running Ubuntu 14.04. Install Docker using the APT repository:

sudo apt-get update
sudo apt-get install apt-transport-https ca-certificates
sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D

Open /etc/apt/sources.list.d/docker.list with your favorite text editor and add the following line:

deb [https://apt.dockerproject.org/repo](https://apt.dockerproject.org/repo) ubuntu-trusty main

Proceed to install Docker on the server:

sudo apt-get update
sudo apt-get install docker-engine
sudo service docker start

2. Build the Docker Image

Log in to Docker Hub (https://hub.docker.com/) and create a new repository. Then, in your terminal, run:

docker login

Enter your username and password when prompted.

In your local development Java Spring folder, create a Dockerfile with the following content:

FROM frolvlad/alpine-oraclejdk8:slim
VOLUME /tmp
ADD target/fleet-beacon*.jar app.jar
EXPOSE 8080
RUN sh -c 'touch /app.jar'
ENTRYPOINT ["java", "-jar", "/app.jar"]

To build the image, execute:

docker build -t username/repo-name .

Here, -t stands for "tag." Replace username and repo-name with your Docker Hub username and repository name. Also, don't forget the trailing dot.

Push the built image to your remote repository:

docker push username/repo-name

3. Pull the Docker Image

On your remote Ubuntu server, log in to Docker and pull the image:

docker pull username/repo-name

Run the container in the background:

docker run -d -p 8080:8080 username/repo-name

Here, -d means "detached," and -p specifies that all exposed ports (e.g., 8080) should be published to the host interfaces.

4. Set Up Nginx

Using the Vim editor, open /etc/nginx/sites-available/default and modify it as follows:

server {
  listen 80 default_server;
  listen [::]:80 default_server ipv6only=on;

  root /usr/share/nginx/html;
  index index.html index.htm;
  server_name localhost;

  location / {
    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-Server $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_pass [http://localhost:8080/](http://localhost:8080/);
  }
}

Exit and save with :wq!.

That's it! Open a browser and navigate to your remote server's IP address; you should see the Java Spring page running smoothly.

5. Troubleshooting

If you encounter an issue with the Docker daemon connection, showing:

Cannot connect to the Docker daemon. Is the Docker daemon running on this host?

Run the following command:

eval $(docker-machine env default)

If you're testing locally and can't find your IP address, use this command to find it:

docker-machine ls

Feel free to leave a comment below if you encounter any other issues.