asynchronous aiohttp requests fails, but synchronous requests succeed

Tim picture Tim · Apr 23, 2015 · Viewed 9.6k times · Source

With the following code I get Cannot connect to host ...:443 ssl:True when I use the asynchronous aiohttp. When I use synchronous requests, it succeeds.

The whitehouse.gov links fail, but the google.com succeeds for both async and sync cases.

What is going wrong? This is with python 3.4.2 on FreeBSD8, aiohttp 0.14.4, requests 2.5.3

import asyncio
import aiohttp
import requests

urls = [
    'http://www.whitehouse.gov/cea/', 
    'http://www.whitehouse.gov/omb', 
    'http://www.google.com']


def test_sync():
    for url in urls:
        r = requests.get(url)
        print(r.status_code)


def test_async():
    for url in urls:
        try:
            r = yield from aiohttp.request('get', url)
        except aiohttp.errors.ClientOSError as e:
            print('bad eternal link %s: %s' % (url, e))
        else:
            print(r.status)


if __name__ == '__main__':
    print('async')
    asyncio.get_event_loop().run_until_complete(test_async())
    print('sync')
    test_sync()

The output from this is:

async
bad eternal link http://www.whitehouse.gov/cea: Cannot connect to host www.whitehouse.gov:443 ssl:True
bad eternal link http://www.whitehouse.gov/omb: Cannot connect to host www.whitehouse.gov:443 ssl:True
200
sync
200
200
200

Answer

Andrew Svetlov picture Andrew Svetlov · Apr 25, 2015

I suspect certificate validation chain is broken on your machine. On Ubuntu everything is working, as @dano mentioned.

Anyway, you may disable ssl validation by creating custom Connector instance:

import asyncio
import aiohttp

urls = [
    'http://www.whitehouse.gov/cea/',
    'http://www.whitehouse.gov/omb',
    'http://www.google.com']


def test_async():
    connector = aiohttp.TCPConnector(verify_ssl=False)
    for url in urls:
        try:
            r = yield from aiohttp.request('get', url, connector=connector)
        except aiohttp.errors.ClientOSError as e:
            print('bad eternal link %s: %s' % (url, e))
        else:
            print(r.status)


if __name__ == '__main__':
    print('async')
    asyncio.get_event_loop().run_until_complete(test_async())

BTW, requests library is shipped with own certificate bundle. Maybe we need to do the same for aiohttp?

UPD. See also https://github.com/aio-libs/aiohttp/issues/341