Set up a simple HTTPS server with asyncio

Overview

I've set up a simple HTTPS server to practice the asyncio module for event loops and the uvloop. uvloop is a module based on asyncio and libuv. Since 2016, new micro-frameworks such as Sanic and japronto that have adopted uvloop have emerged.

Premise

It assumes Python 3.6. In Python 3.6, the SSLContext default values for the ssl module have been changed and constants have been consolidated.

About uvloop

uvloop implements ʻasyncio.AbstractEventLoop` and provides an API compatible with uvloop. Due to libuv constraints, uvloop does not support Windows, so asyncio is responsible for the uvloop fallback.

Create a self-signed certificate

You can create a self-signed certificate with the following one-liner.

# https://stackoverflow.com/a/41366949/531320
openssl req -x509 -newkey rsa:4096 -sha256 \
-nodes -keyout server.key -out server.crt \
-subj "/CN=example.com" -days 3650

Set up an HTTPS server

Let's set up an echo server that returns a string regardless of the HTTP method.

server.py

import asyncio
import ssl

async def request_handler(reader, writer):
    msg = (
      'HTTP/1.1 200 OK\r\n'
      'Content-Type: text/plain; charset=utf-8\r\n'
      '\r\n'
      'hello\r\n'
    )
    writer.write(msg.encode())
    await writer.drain()
    writer.close()

host = '127.0.0.1'
port = 8000

ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
ctx.load_cert_chain('server.crt', keyfile='server.key')
ctx.options |= ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1

loop = asyncio.get_event_loop()
coro = asyncio.start_server(
  request_handler, 
  host, port, ssl=ctx, loop=loop
)
server = loop.run_until_complete(coro)

print('Serving on {}'.format(server.sockets[0].getsockname()))

try:
    loop.run_forever()
except KeyboardInterrupt:
    pass

server.close()
loop.run_until_complete(server.wait_closed())
loop.close()

Create an HTTPS client

Now let's create an HTTPS client.

client.py

import asyncio
import ssl

async def http_client(host, port, msg, ctx, loop):
    reader, writer = await asyncio.open_connection(
        host, port, ssl=ctx, loop=loop
    )

    writer.write(msg.encode())
    data = await reader.read()
    print("Received: %r" % data.decode())
    writer.close()

host = '127.0.0.1'
port = 8000
msg = (
  'GET / HTTP/1.1\r\n'
  'Host: localhost:8000\r\n'
  '\r\n'
  '\r\n'
)

ctx = ssl.create_default_context()
ctx.options |= ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1
ctx.check_hostname = False
ctx.verify_mode = ssl.CERT_NONE

loop = asyncio.get_event_loop()
loop.run_until_complete(http_client(host, port, msg, ctx, loop))
loop.close()

aiohttp

aiohttp is an HTTP module developed based on asyncio, and also comes with application development functions. The installation is as follows:

pip3 install aiohttp

Let's set up a server that displays HTML files.

server.py

from aiohttp import web
from pathlib import Path
import ssl

host='localhost'
port=8000
ctx = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
ctx.load_cert_chain('server.crt', keyfile='server.key')
ctx.options |= ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1

app = web.Application()
app.router.add_static('/static', path=str(Path.cwd().joinpath('static')), show_index=True)
web.run_app(app, host=host, port=port, ssl_context=ctx)