Greengrass china endpoint (#198)

* Temporary fix for connection with greengrass china endpoint * replace '-' with '.' * add optional parameter for endpoint * update comment on region usage * add type hint

Author: jmklix

awsiot/greengrass_discovery.py

@@ -17,7 +17,8 @@ class DiscoveryClient:
  bootstrap: Client bootstrap
  socket_options: Socket options
  tls_context: Client TLS context
- region: AWS region
+ region: AWS region (not used if gg_server_name is set)
+ gg_server_name: optional full server name
  """
  __slots__ = [
  '_bootstrap',
@@ -34,16 +35,23 @@ def __init__(
  bootstrap: ClientBootstrap,
  socket_options: SocketOptions,
  tls_context: ClientTlsContext,
- region: str):
+ region: str,
+ gg_server_name: str = None):
  assert isinstance(bootstrap, ClientBootstrap)
  assert isinstance(socket_options, SocketOptions)
  assert isinstance(tls_context, ClientTlsContext)
  assert isinstance(region, str)
+ if gg_server_name is not None: 
+ assert isinstance(gg_server_name, str)
 
  self._bootstrap = bootstrap
  self._socket_options = socket_options
  self._region = region
- self._gg_server_name = 'greengrass-ats.iot.{}.amazonaws.com'.format(region)
+ if gg_server_name is None:
+ self._gg_server_name = 'greengrass-ats.iot.{}.amazonaws.com'.format(region)
+ else:
+ self._gg_server_name = gg_server_name
+
  self._tls_connection_options = tls_context.new_connection_options()
  self._tls_connection_options.set_server_name(self._gg_server_name)
  self.port = 8443