Nicely handle the missing connectivity case

On Jul 16, 2013, at 02:37 PM, Stéphane Graber wrote:

>Currently when running system-image-cli on a system without internet
>access, I get 2-3 stacktraces with the most relevant one showing a no
>route to host, I think this may be worth catching and showing a single
>error message saying that the update server can't be reached.

Can you paste the traceback? This will almost certainly change anyway when
the dbus d/l service is integrated.

root@ubuntu-phablet:/# system-image-cli
Jul 16 15:12:32 2013 (1618) uncaught exception in state machine
Traceback (most recent call last):
  File "/usr/lib/python3.3/urllib/request.py", line 1248, in do_open
    h.request(req.get_method(), req.selector, req.data, headers)
  File "/usr/lib/python3.3/http/client.py", line 1061, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python3.3/http/client.py", line 1099, in _send_request
    self.endheaders(body)
  File "/usr/lib/python3.3/http/client.py", line 1057, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python3.3/http/client.py", line 902, in _send_output
    self.send(msg)
  File "/usr/lib/python3.3/http/client.py", line 840, in send
    self.connect()
  File "/usr/lib/python3.3/http/client.py", line 1194, in connect
    self.timeout, self.source_address)
  File "/usr/lib/python3.3/socket.py", line 435, in create_connection
    raise err
  File "/usr/lib/python3.3/socket.py", line 426, in create_connection
    sock.connect(sa)
OSError: [Errno 101] Network is unreachable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/systemimage/download.py", line 172, in get_files
    list(tpe.map(_get_one_file, args))
  File "/usr/lib/python3.3/concurrent/futures/_base.py", line 546, in result_iterator
    yield future.result()
  File "/usr/lib/python3.3/concurrent/futures/_base.py", line 399, in result
    return self.__get_result()
  File "/usr/lib/python3.3/concurrent/futures/_base.py", line 351, in __get_result
    raise self._exception
  File "/usr/lib/python3.3/concurrent/futures/thread.py", line 54, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/lib/python3/dist-packages/systemimage/download.py", line 73, in _get_one_file
    response = stack.enter_context(Downloader(url, timeout))
  File "/usr/lib/python3.3/contextlib.py", line 216, in enter_context
    result = _cm_type.__enter__(cm)
  File "/usr/lib/python3/dist-packages/systemimage/download.py", line 58, in __enter__
    urlopen(request, timeout=self.timeout, cadefault=True))
  File "/usr/lib/python3.3/urllib/request.py", line 156, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib/python3.3/urllib/request.py", line 469, in open
    response = self._open(req, data)
  File "/usr/lib/python3.3/urllib/request.py", line 487, in _open
    '_open', req)
  File "/usr/lib/python3.3/urllib/request.py", line 447, in _call_chain
    result = func(*args)
  File "/usr/lib/python3.3/urllib/request.py", line 1283, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "/usr/lib/python3.3/urllib/request.py", line 1251, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [Errno 101] Network is unreachable>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 92, in __next__
    step()
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 223, in _get_channel
    (asc_url, asc_path),
  File "/usr/li...

So, I'm going to mark this bug as Invalid since the integration of u-d-m changes everything, and should greatly improve the situation. If it crops up again, let's open a new bug.