Docker is a powerful tool that allows developers to create, deploy, and run applications in containers. By using a Dockerfile, you can automate the process of creating Docker images. In this guide, we will show you how to create Docker images using a Dockerfile on Ubuntu 18.04 LTS. Whether you are using a Windows VPS UK or other hosting platforms, Docker provides a flexible environment for building containerized applications.

Prerequisites

Before you begin, ensure you have the following:

• An Ubuntu 18.04 LTS server, which can be hosted on a UK Windows VPS, Windows Virtual Private Servers, or another Windows VPS Hosting UK solution.
• Docker installed on your server.
• Basic knowledge of Docker and Dockerfile.

Step 1: Install Docker

If Docker is not already installed, you can install it by running the following commands:

sudo apt update
sudo apt install apt-transport-https ca-certificates curl software-properties-common
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
sudo apt update
sudo apt install docker-ce -y

Once installed, start Docker and enable it to run at startup:

sudo systemctl start docker
sudo systemctl enable docker

Step 2: Create a Dockerfile

A Dockerfile is a text document that contains all the commands needed to assemble an image. First, create a directory for your Docker project and navigate into it:

mkdir ~/mydockerapp
cd ~/mydockerapp

Next, create a Dockerfile:

nano Dockerfile

In this example, we will create a simple Dockerfile to build a Python application. Add the following content to the Dockerfile:

FROM python:3.8-slim

WORKDIR /app

COPY . /app

RUN pip install --no-cache-dir -r requirements.txt

CMD ["python", "app.py"]

Explanation of the Dockerfile commands:

• FROM: Specifies the base image (in this case, Python 3.8).
• WORKDIR: Sets the working directory inside the container.
• COPY: Copies the current directory's content into the container.
• RUN: Executes commands inside the container (e.g., installing dependencies).
• CMD: Specifies the command to run when the container starts.

Step 3: Create Your Application Files

Create a simple Python application file called app.py:

nano app.py

Add the following content:

print("Hello, World from Docker!")

Next, create a requirements.txt file for any dependencies (even if it’s empty for now):

nano requirements.txt

Leave it empty or add any necessary Python packages.

Step 4: Build the Docker Image

Now, you can build the Docker image using the Dockerfile. Run the following command:

docker build -t mydockerapp .

The -t flag allows you to tag the image (in this case, "mydockerapp"). The . at the end specifies that Docker should use the current directory as the build context.

Step 5: Run the Docker Container

Once the image is built, you can run the container with the following command:

docker run mydockerapp

You should see the output:

Hello, World from Docker!

Step 6: List Docker Images and Containers

To list all Docker images on your system, run:

docker images

To list all running containers, run:

docker ps

Conclusion

By following these steps, you have successfully created a Docker image using a Dockerfile and run the image inside a container on Ubuntu 18.04 LTS. Whether you’re hosting your Docker applications on a Windows VPS UK, Windows VPS Italy, or another Windows Virtual Private Server Hosting environment, Docker provides a powerful and flexible platform for containerized applications.