Proxy connections requiring authentication are failing

[danielmitterdorfer]

Rally version (get with esrally --version): 1.0.3

Steps to reproduce:

1. Setup an HTTP proxy server that requires authentication
2. export http_proxy=http://username:[email protected]:8080
3. Invoke Rally

Expected behavior:

Rally uses the proxy to connect to the Internet

Actual behavior:

Rally reports that no Internet connection is available. On the command line we can see.

[WARNING] No Internet connection detected. Automatic download of track data sets etc. is disabled. 

Provide logs (if relevant):

2019-01-23 15:19:43,262 -not-actor-/PID:16740 esrally.utils.net INFO Rally connects via proxy URL [http://username:[email protected]:8080] to the Internet (picked up from the environment variable [http_proxy]).
2019-01-23 15:19:43,263 -not-actor-/PID:16740 esrally.utils.net DEBUG Checking for internet connection against [https://github.com/]
2019-01-23 15:19:43,347 -not-actor-/PID:16740 esrally.utils.net DEBUG Could not detect a working Internet connection
Traceback (most recent call last):
  File "/usr/local/python3/lib/python3.6/site-packages/urllib3/connectionpool.py", line 595, in urlopen
    self._prepare_proxy(conn)
  File "/usr/local/python3/lib/python3.6/site-packages/urllib3/connectionpool.py", line 816, in _prepare_proxy
    conn.connect()
  File "/usr/local/python3/lib/python3.6/site-packages/urllib3/connection.py", line 294, in connect
    self._tunnel()
  File "/usr/local/python3/lib/python3.6/http/client.py", line 919, in _tunnel
    message.strip()))
OSError: Tunnel connection failed: 407 Proxy Authentication Required

Analysis:

The problem is that Python does not take the provided credentials in the URL into account. Thus, Rally needs to provide them separately using a ProxyBasicAuthHandler.