Catch connection errors and improve error messages

Bắt đầu bằng cách lần theo luồng deliver qua datadelivery/commands.py và datadelivery/s3.py, đặc biệt là _get_current_endpoint và _get_request, sau đó tái hiện lệnh với một API URL không khả dụng. Hoàn thành khi lỗi kết nối HTTP được báo cáo dưới dạng một lỗi ngắn gọn dành cho người dùng thay vì traceback đầy đủ.

I had a stale configuration my ~/.datadelivery.yml file, pointing to a URL that's not live:

url: http://127.0.0.1:8000/api/v2/

When I tried to run a deliver command, I get the following:

$ datadelivery deliver -b sample --email [email protected]
Traceback (most recent call last):
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/connection.py", line 141, in _new_conn
    (self.host, self.port), self.timeout, **extra_kw)
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/util/connection.py", line 83, in create_connection
    raise err
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/util/connection.py", line 73, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 61] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/connectionpool.py", line 601, in urlopen
    chunked=chunked)
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/connectionpool.py", line 357, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1239, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1285, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1234, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1026, in _send_output
    self.send(msg)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 964, in send
    self.connect()
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/connection.py", line 166, in connect
    conn = self._new_conn()
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/connection.py", line 150, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x10af6c908>: Failed to establish a new connection: [Errno 61] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/requests-2.18.4-py3.6.egg/requests/adapters.py", line 440, in send
    timeout=timeout
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/connectionpool.py", line 639, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/urllib3-1.22-py3.6.egg/urllib3/util/retry.py", line 388, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='127.0.0.1', port=8000): Max retries exceeded with url: /api/v2/s3-endpoints/?name=default (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x10af6c908>: Failed to establish a new connection: [Errno 61] Connection refused',))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/bin/datadelivery", line 11, in <module>
    load_entry_point('datadelivery==0.0.1', 'console_scripts', 'datadelivery')()
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/__main__.py", line 14, in main
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/argparser.py", line 26, in parse_and_run_commands
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/argparser.py", line 73, in _run_deliver
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/commands.py", line 24, in deliver
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/commands.py", line 14, in _create_s3
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/s3.py", line 11, in __init__
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/s3.py", line 62, in _get_current_endpoint
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/datadelivery-0.0.1-py3.6.egg/datadelivery/s3.py", line 27, in _get_request
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/requests-2.18.4-py3.6.egg/requests/api.py", line 72, in get
    return request('get', url, params=params, **kwargs)
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/requests-2.18.4-py3.6.egg/requests/api.py", line 58, in request
    return session.request(method=method, url=url, **kwargs)
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/requests-2.18.4-py3.6.egg/requests/sessions.py", line 508, in request
    resp = self.send(prep, **send_kwargs)
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/requests-2.18.4-py3.6.egg/requests/sessions.py", line 618, in send
    r = adapter.send(request, **kwargs)
  File "/Users/dcl9/Code/python/datadelivery-cli/venv/lib/python3.6/site-packages/requests-2.18.4-py3.6.egg/requests/adapters.py", line 508, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=8000): Max retries exceeded with url: /api/v2/s3-endpoints/?name=default (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x10af6c908>: Failed to establish a new connection: [Errno 61] Connection refused',))
$ 

While we don't expect end-users to override their API url here, HTTP connection errors should be expected and relayed more succintcly :)