How to use the command 'waitress-serve' (with examples)

‘waitress-serve’ is a pure Python WSGI HTTP server that allows you to run Python web applications. It provides a simple and efficient way to serve WSGI applications and can be easily configured to meet your specific needs.

Use case 1: Run a Python web app

Code:

waitress-serve import.path:wsgi_func

Motivation: This use case is useful when you have a Python web application and you want to run it using the ‘waitress-serve’ command. By specifying the import path and the WSGI function, you can start serving your application using the waitress server.

Explanation:

• import.path is the path to the Python module containing the WSGI function.
• wsgi_func is the WSGI function that will be used to serve the application.

Example output: The Python web app will be running and accessible on the default host and port.

Use case 2: Listen on port 8080 on localhost

Code:

waitress-serve --listen=localhost:8080 import.path:wsgi_func

Motivation: This use case is useful when you want to specify a custom port and hostname for your Python web application. By using the ‘–listen’ flag, you can set the desired hostname and port number.

Explanation:

• –listen=localhost:8080 specifies that the server should listen on ’localhost’ with port number ‘8080’.
• import.path:wsgi_func is the same as in the previous use case, specifying the import path and the WSGI function.

Example output: The Python web app will be running and accessible on ’localhost’ with port number ‘8080’.

Use case 3: Start waitress on a Unix socket

Code:

waitress-serve --unix-socket=path/to/socket import.path:wsgi_func

Motivation: This use case is useful when you want to start the waitress server on a Unix socket instead of a port and hostname. By using the ‘–unix-socket’ flag, you can specify the path to the Unix socket.

Explanation:

• –unix-socket=path/to/socket specifies the path to the Unix socket.
• import.path:wsgi_func is the same as in the previous use cases, specifying the import path and the WSGI function.

Example output: The Python web app will be running and accessible through the Unix socket specified.

Use case 4: Use 4 threads to process requests

Code:

waitress-serve --threads=4 import.path:wsgifunc

Motivation: This use case is useful when you want to control the number of threads used to process requests. By using the ‘–threads’ flag, you can specify the desired number of threads.

Explanation:

• –threads=4 specifies that the server should use 4 threads to process requests.
• import.path:wsgifunc is the same as in the previous use cases, specifying the import path and the WSGI function.

Example output: The Python web app will be running with 4 threads handling incoming requests.

Use case 5: Call a factory method that returns a WSGI object

Code:

waitress-serve --call import.path.wsgi_factory

Motivation: This use case is useful when you have a factory method that returns a WSGI object instead of a WSGI function. By using the ‘–call’ flag, you can specify the import path to the factory method that will be called.

Explanation:

• –call import.path.wsgi_factory specifies that the server should call the factory method ‘wsgi_factory’ from the module specified by ‘import.path’.
• The factory method should return a WSGI object.

Example output: The Python web app will be running using the WSGI object returned by the factory method.

Use case 6: Set the URL scheme to HTTPS

Code:

waitress-serve --url-scheme=https import.path:wsgi_func

Motivation: This use case is useful when you want to serve your Python web application over HTTPS instead of HTTP. By using the ‘–url-scheme’ flag, you can set the URL scheme to ‘https’.

Explanation:

• –url-scheme=https specifies that the server should use ‘https’ as the URL scheme.
• import.path:wsgi_func is the same as in the previous use cases, specifying the import path and the WSGI function.

Example output: The Python web app will be running and accessible over HTTPS.

Conclusion:

The ‘waitress-serve’ command provides different use cases for running Python web applications. By understanding how to use the different command-line options, you can configure the server according to your specific needs. Whether you need to run a web app, specify custom ports or hostnames, use Unix sockets, control the number of threads, call factory methods, or serve over HTTPS, ‘waitress-serve’ has you covered.