Simple TCP server that echo everything with prepended HTTP response headers.

http_echo.py

#!/usr/bin/env python3
import asyncio
from asyncio import StreamReader, StreamWriter


LISTEN = ('::', 8080)
WAIT_SECS = 3
BUF_SIZE = 4096
HTTP_RESPONSE = [
    'HTTP/1.1 200 OK',
    'Server: http_echo',
    'Connection: Closed',
    'Content-Type: text/plain'
]


async def handle_client(reader: StreamReader, writer: StreamWriter):
    peer = writer.get_extra_info('peername')
    print(f'Accept {peer}')

    head = '\r\n'.join(HTTP_RESPONSE) + '\r\n\r\n'
    writer.write(head.encode())
    await writer.drain()

    try:
        while not reader.at_eof():
            data = await asyncio.wait_for(reader.read(BUF_SIZE), WAIT_SECS)
            if data:
                writer.write(data)
                await writer.drain()
    except TimeoutError:
        pass

    writer.write_eof()
    writer.close()
    await writer.wait_closed()


async def main():
    server = await asyncio.start_server(handle_client, *LISTEN)
    addrs = ', '.join(str(sock.getsockname()) for sock in server.sockets)
    print(f'Listen on {addrs}')
    async with server:
        await server.serve_forever()


if __name__ == '__main__':
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        pass