Docker is a powerful tool for automating the deployment of applications using containerization. One of Docker’s core functionalities is building images using a Dockerfile, which is a script that contains a series of instructions for building a Docker image. In this guide, we will show you how to create Docker images with a Dockerfile on Ubuntu 20.04 LTS. Whether you're using a Windows VPS UK or another VPS solution, this guide will help you streamline your containerization process.

Prerequisites

Before you begin, make sure you have the following:

• An Ubuntu 20.04 LTS server, which could be hosted on a UK Windows VPS, Windows Virtual Private Server Hosting, or another VPS Windows Servers.
• Docker installed on your server.
• Root or sudo privileges on your server.

Step 1: Install Docker

If Docker is not installed on your Ubuntu 20.04 system, you can install it by following these steps. Start by updating your package list:

sudo apt update && sudo apt upgrade

Next, install the necessary dependencies:

sudo apt install apt-transport-https ca-certificates curl software-properties-common

Add Docker’s GPG key and the Docker repository:

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 focal stable"

Now, install Docker:

sudo apt update
sudo apt install docker-ce

Once installed, start and enable Docker:

sudo systemctl start docker
sudo systemctl enable docker

Step 2: Create a Dockerfile

To create a Docker image, you need to define a Dockerfile. This file contains the instructions Docker will use to build the image. Start by creating a new directory for your Dockerfile:

mkdir ~/mydockerapp
cd ~/mydockerapp

Now create a Dockerfile using your preferred text editor:

nano Dockerfile

Here is an example of a simple Dockerfile for a Python application:

FROM python:3.8-slim-buster

WORKDIR /app

COPY . /app

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

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

In this example:

• FROM: Specifies the base image (Python 3.8-slim-buster).
• WORKDIR: Sets the working directory inside the container.
• COPY: Copies files from the host machine to the container.
• RUN: Executes commands (e.g., installing Python dependencies).
• CMD: Specifies the command to run when the container starts.

Step 3: Build the Docker Image

Once your Dockerfile is ready, you can build the Docker image using the docker build command. Run the following command to build the image:

sudo docker build -t mydockerapp .

This command builds the image using the Dockerfile in the current directory and tags the image as mydockerapp. You can replace mydockerapp with your preferred image name.

Step 4: Run the Docker Container

After building the image, you can run a container based on it using the docker run command. For example:

sudo docker run -d -p 8080:8080 mydockerapp

This command runs the container in detached mode (-d) and maps port 8080 on the host to port 8080 in the container.

Step 5: Verify the Running Container

You can verify that the container is running by using the docker ps command:

sudo docker ps

This will display the running containers along with their status and port mappings.

Step 6: Push the Docker Image to a Registry (Optional)

If you want to share your Docker image with others or use it in different environments like Windows VPS UK or Windows VPS Italy, you can push the image to a Docker registry like Docker Hub. First, log in to Docker Hub:

sudo docker login

Then, tag the image with your Docker Hub username:

sudo docker tag mydockerapp your-dockerhub-username/mydockerapp

Finally, push the image to Docker Hub:

sudo docker push your-dockerhub-username/mydockerapp

Conclusion

By following these steps, you have successfully created a Docker image using a Dockerfile on Ubuntu 20.04 LTS. Whether you're working in a Windows VPS UK, Windows Virtual Dedicated Server Hosting, or another server environment, Docker simplifies the process of building and deploying applications in containers.