Build Python Flask App using Docker

Docker is a tool designed to make it easier to create, deploy, and run applications by using containers. Containers allow a developer to package up an application with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package.

One of the main advantages of using Docker is that it allows developers to create consistent, reproducible environments for their applications. This can be especially useful when working with different teams or in different environments, as it ensures that the application will behave the same regardless of where it is deployed.

Another advantage of Docker is that it allows developers to easily scale their applications. Because containers are lightweight and can be easily deployed on multiple servers, it is simple to scale up or down as needed.

Now, let’s look at how to use Docker with a simple Python Flask application. Flask is a microweb framework written in Python, and it is a popular choice for building web applications.

Here is an example of a simple Python Flask application that you can use with Docker:

from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello, World!"

if __name__ == "__main__":
    app.run()

This code creates a Flask application with a single route, /, which returns the string "Hello, World!". When you run the application, you will be able to access this route by visiting http://localhost:5000/ in your web browser.

First, you will need to install Docker on your machine. Then, create a new file called Dockerfile in the root directory of your Flask application and add the following contents:

FROM python:3.8

WORKDIR /app

COPY requirements.txt .

RUN pip install -r requirements.txt

COPY . .

EXPOSE 5000

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

This Dockerfile specifies the base image that we will use (in this case, Python 3.8), the working directory for the application, and the commands that will be run when the container is built.

Next, create a requirements.txt file that lists all of the dependencies for your application. For example:

flask

Finally, build the Docker image by running the following command:

docker build -t myapp .

This will build the Docker image with the name “myapp”.

To run the application in a Docker container, use the following command:

docker run -p 5000:5000 myapp

This will run the Docker container and expose the Flask application on port 5000.

Using Docker with a Python Flask application is a great way to ensure that your application is portable and can be easily deployed in different environments. It is also a valuable skill for any DevOps engineer to have, as Docker is widely used in the industry for building, deploying, and running applications.

I hope this tutorial has been helpful and gives you a good starting point for using Docker with Python Flask. Happy coding!