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 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 VPSVirtual Private Server Hosting, or another VPS Windows VPS 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 or Microsoft SQL VPS Windows, 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, or another server environment, Docker simplifies the process of building and deploying applications in containers.