How to quickly deploy Flask applications

How to quickly deploy Flask applications requires specific code examples

Flask is a lightweight Python web application framework with a simple, clear, flexible and scalable design concept. Used by more and more Python developers. However, deploying a Flask application to a server can be tricky for newbies.

This article will introduce how to quickly deploy Flask applications to the server and provide specific code examples.

Step 1: Install the necessary software

Before you start deploying the Flask application, you need to install the necessary software tools. The software that needs to be installed is listed below:

1. Apache or Nginx as the web server
2. WSGI interface
3. Flask framework

Steps 2: Create a Flask application

In this example, we use the following code snippet to create a Flask application:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return 'Hello, World!'
    
if __name__ == '__main__':
    app.run()

This code will create a simple Flask application. When we access it in the browser When accessing the website, "Hello, World!" will be returned.

Step 3: Install mod_wsgi

Now, we need to install mod_wsgi according to the server's operating system.

On Ubuntu, you can install it with the following command:

sudo apt-get install libapache2-mod-wsgi-py3

On CentOS, you need to use the following command to install it:

sudo yum install mod_wsgi

Step 4: Configure Apache or Nginx

To deploy the Flask application to the server, we need to configure Apache or Nginx. In this example, we will use Apache as the web server.

First, you need to specify the directory of the Flask application in the Apache configuration file.

On Ubuntu, the configuration file path is /etc/apache2/sites-available/000-default.conf.

On CentOS, the configuration file path is /etc/httpd/conf/httpd.conf.

After opening the configuration file, add the following content:

WSGIDaemonProcess myapp threads=5
WSGIScriptAlias / /var/www/html/myapp.wsgi

<Directory /var/www/html/>
    WSGIProcessGroup myapp
    WSGIApplicationGroup %{GLOBAL}
    Order deny,allow
    Allow from all
</Directory>

Here, myapp refers to the name of the Flask application, and threads=5 means using 5 processes to handle requests. myapp.wsgi is a WSGI script used to connect Flask applications with Apache.

Next, we need to create the myapp.wsgi file.

#!/usr/bin/python
import sys
import logging
logging.basicConfig(stream=sys.stderr)
sys.path.insert(0,"/var/www/html/")
from myapp import app as application

This file will go into the root directory of the Flask application and import the app variables in the application.

Step 5: Restart Apache

If everything went well, we can now restart Apache and check whether the Flask application has been successfully deployed.

On Ubuntu, you can use the following command to restart Apache:

sudo service apache2 restart

On CentOS, you need to use the following command:

sudo systemctl restart httpd.service

Now, open the server in the browser IP address, you can see "Hello, World!".

Summary

In this article, we introduce how to quickly deploy Flask applications and provide specific code examples. Although deploying Flask applications may be tricky for novices, as long as you follow the above steps, I believe everyone can successfully deploy Flask applications to the server and provide services on the network.

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