Is Flask a Web Server?


Angela Bailey

Flask is a popular Python web framework that is often used to develop web applications. However, it is important to understand that Flask itself is not a web server. Instead, Flask is a microframework that allows you to build web applications by providing the necessary tools and functionalities.

What is a Web Server?
Before diving into the specifics of Flask, let’s first clarify what a web server actually is. In simple terms, a web server is a software that handles HTTP requests sent by clients, such as web browsers, and returns responses with the requested resources.

Common Web Servers
There are many web servers available in the market today. Some of the most popular ones include:

  • Apache HTTP Server: Apache is one of the oldest and most widely used web servers. It is known for its stability and flexibility.
  • Nginx: Nginx is another highly popular web server known for its high performance and scalability.
  • Microsoft Internet Information Services (IIS): IIS is Microsoft’s proprietary web server software for Windows servers.

Flask as a Web Framework
Now that we have established what a web server actually does, let’s talk about Flask’s role in the bigger picture. As mentioned earlier, Flask is not a standalone web server but rather a microframework. It provides you with the necessary tools and functionalities to build your own web application.

How Does Flask Work?

When you develop a Flask application, you write Python code to define routes (URL patterns) and their corresponding view functions (Python functions). These view functions handle incoming HTTP requests and return responses based on your application logic.

Flask uses WSGI (Web Server Gateway Interface) to communicate with the underlying web server. WSGI is a specification that defines how a web server should communicate with web applications written in Python.

Running Flask Applications

To run a Flask application, you typically need to deploy it on a web server. This can be done using various deployment options, such as:

  • Development Server: Flask provides a built-in development server that you can use for testing and development purposes. However, it is not suitable for production environments.
  • Production Server: In a production environment, you would typically deploy your Flask application on a dedicated web server like Apache or Nginx.

    These servers act as the interface between the internet and your Flask application.

  • Platform-as-a-Service (PaaS) Providers: Alternatively, you can deploy your Flask application on PaaS providers like Heroku or AWS Elastic Beanstalk. These platforms handle the underlying infrastructure and deployment for you.

The Role of Web Servers with Flask

In the context of Flask, the web server’s primary role is to handle incoming HTTP requests and forward them to your Flask application. The web server listens on a specific port (e.g., port 80 for HTTP) and routes incoming requests based on their URLs.

Flask itself does not have the capability to handle incoming requests directly from clients over the internet. Instead, it relies on an external web server to perform this task.

The Bottom Line
In conclusion, while Flask is not a web server itself, it provides you with the necessary tools and functionalities to build web applications. To run your Flask application in a production environment, you will need to deploy it on a separate web server like Apache or Nginx.

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