Minimal Python Webserver

main.py

"""
# Minimal Python Webserver (adopted from https://de.wikipedia.org/wiki/Socket_(Software)#Server)

## Notes

- It does not close the socket on exit (e.g. on interrupt) => it may take some time until the OS releases the port for reuse.
- It does not speak HTTP yet - you need to implement it yourself.
- It does not read the full client request, just the first 1024 bytes. Then, it sends its answer. When implementing HTTP, you need to first read all headers (=> until you receive `\r\n\r\n` = blank line). Using the headers, you need to identify whether a message body will follow. In the easiest case (other cases are out of scope for here), a `Content-Length` header signalizes how many bytes of message body will follow. With this number, you know how many bytes you need to read to receive the full request.
- Don't name the file `socket.py`. This will result in a (Python-specific) error.

"""

import socket

host = "127.0.0.1"  # IP adress of the server
port = 5000  # Port used by the server

s = socket.socket()
s.bind((host, port))
s.listen()

while True:
    client, addr = s.accept()
    print(f"Connected to {addr}")

    data = client.recv(1024)
    if not data:
        client.close()

    print(f"Received from client: {data.decode()}")
    client.sendall(data)
    client.close()

For responding with HTTP (minimal example), replace the line client.sendall(...) with:

    client.sendall(b"""HTTP/1.1 200 OK

""")

Notes

• b => bytes literal (see https://www.studytonight.com/post/significance-of-prefix-b-in-a-string-in-python for more)
• The empty line before the closing quotes is important (or you will receive a "socket hung up" error)
• When using the """ notation in Python, youy need to make sure every line does not contain leading whitespace (this whitespace will end up in the string!).