This blog post will walk you through the process of dockerizing a Python application, that is, packaging a Python application into a Docker image.
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  • A Linux system with Docker installed and running
  • A root user or a user account with sudo privileges

Preparing a Python environment

Before starting, you will need to install a Python package and additional Python dependencies on your system.

Let's use the apt command to install all required packages.

apt install python3 python3-pip python3.10-venv -y

Then, create a directory to store your application.

mkdir app

Next, change the directory to your app directory.

cd app

Next, create a Python virtual environment to isolate all dependencies.

python3 -m venv python-app

After that, activate the virtual environment.

source python-app/bin/activate

Then, install the Flask package using the PIP command.

pip3 install Flask
Installing the Flask application

Installing the Flask application

Creating a Python application

Your Python virtual environment is now ready to create and deploy a Python application.

First, create an for your Python application.


Add the following Python code:

# Import the Flask module for your application and define your app.
from flask import Flask, render_template
app = Flask(__name__)
# Define the basic route and the request handler.
def home():
return render_template('index.html')
# Run the application.
if __name__ == '__main__':,host='')

Save and close the file.

Then, create a templates directory and an HTML file for your application.

mkdir templates
nano templates/index.html

Add the following HTML code:

<!DOCTYPE html>
    <meta charset="utf-8" />
        .multicolor-text {
            text-align: center;
            font-size: 50px;
            background: linear-gradient(to left,
            -webkit-background-clip: text;
            color: transparent;

    <div class="multicolor-text">
        Dockerizing a Python application: A step-by-step tutorial!

Save and close the file. Then, create a requirements.txt file to define any dependency that your application needs.

nano requirements.txt

Add the following dependency:


Save and close the file.

Finally, run your Python application locally.


If everything is OK, you will see the following screen:

Starting the Python application

Starting the Python application

Your application is now running and listening on Port 5000. You can access it using the URL http://your-server-ip:5000 in your web browser.

Verifying the Python application

Verifying the Python application

Dockerizing a Python application

A Dockerfile is a text file that contains a set of instructions for building a Docker image from your local application.

Let's create a Dockerfile in your application directory.

nano Dockerfile

Add the following configuration to build a docker image from your application code.

FROM python:3.8
COPY . .
RUN pip install -r requirements.txt
CMD ["python",""]

Save and close the file when you are done.

Here is a brief explanation of each command used in the above file.

  • FROM: Specify a Python base image that matches your application's requirements.
  • WORKDIR: Define a working directory for your application.
  • COPY: Copy your application's source code and files into the container.
  • RUN: Specify a command to install all required dependencies inside the container.
  • CMD: Specify a command to run your Python application inside the container.

Build and run a Python app in a container

At this point, your Dockerfile is ready to build the Docker image.

Let's build the docker container image using the docker build command.

docker build -t python-app .

This will build the image named python-app using the specified Dockerfile.

Building a docker image from a dockerfile

Building a docker image from a dockerfile

Verify your built Docker image using the following command:

docker images

You will see your python-app Docker image on the following screen.

Listing docker images

Listing docker images

Finally, create and run python-app containers from your built image.

docker run -dit --name python-app -p 8080:5000 python-app

The above command will create a new container from the python-app docker image and map Port 8080 on your host to Port 5000 in the container.

You can also verify your running container using the below command:

docker ps

You will see the status of your python-app container on the following screen.

Showing the status of the running container

Showing the status of the running container

Now, open your web browser and verify your Python application is running inside a container using the URL http://your-server-ip:8080. You will see the following screen:

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Verifying the Python application running inside the container

Verifying the Python application running inside the container


In this post, you learned how to package a Python application into a Docker image and run it in an isolated environment. Dockerizing Python applications will improve your deployment process and streamline all your deployment workflows.


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