1111 **client_id** (`str`): ID to place in CONNECT packet. Must be unique across all devices/clients.
1212 If an ID is already in use, the other client will be disconnected.
1313
14- Optional Keyword Arguments:
14+ Optional Keyword Arguments (omit, or set `None` to get default value) :
1515
1616 **on_connection_interrupted** (`Callable`): Callback invoked whenever the MQTT connection is lost.
1717 The MQTT client will automatically attempt to reconnect.
@@ -106,6 +106,20 @@ def _check_required_kwargs(**kwargs):
106106 raise TypeError ("Builder needs keyword-only argument '{}'" .format (required ))
107107
108108
109+ def _get (kwargs , name , default = None ):
110+ """
111+ Returns kwargs['name'] if it exists and is not None.
112+ Otherwise returns default.
113+
114+ This function exists so users can pass some_arg=None to get its default
115+ value, instead of literally passing None.
116+ """
117+ val = kwargs .get (name )
118+ if val is None :
119+ val = default
120+ return val
121+
122+
109123_metrics_str = None
110124
111125
@@ -132,64 +146,64 @@ def _builder(
132146 websocket_proxy_options = None ,
133147 ** kwargs ):
134148
135- ca_bytes = kwargs . get ( 'ca_bytes' )
136- ca_filepath = kwargs . get ( 'ca_filepath' )
137- ca_dirpath = kwargs . get ( 'ca_dirpath' )
149+ ca_bytes = _get ( kwargs , 'ca_bytes' )
150+ ca_filepath = _get ( kwargs , 'ca_filepath' )
151+ ca_dirpath = _get ( kwargs , 'ca_dirpath' )
138152 if ca_bytes :
139153 tls_ctx_options .override_default_trust_store (ca_bytes )
140154 elif ca_filepath or ca_dirpath :
141155 tls_ctx_options .override_default_trust_store_from_path (ca_dirpath , ca_filepath )
142156
143- if use_websockets :
144- port = 443
145- if awscrt .io .is_alpn_available ():
146- tls_ctx_options .alpn_list = ['http/1.1' ]
147- else :
148- port = 8883
149- if awscrt .io .is_alpn_available ():
157+ port = _get (kwargs , 'port' )
158+ if port is None :
159+ # prefer 443, even for direct MQTT connections, since it's less likely to be blocked by firewalls
160+ if use_websockets or awscrt .io .is_alpn_available ():
150161 port = 443
151- tls_ctx_options .alpn_list = ['x-amzn-mqtt-ca' ]
162+ else :
163+ port = 8883
152164
153- port = kwargs .get ('port' , port )
165+ if port == 443 and awscrt .io .is_alpn_available ():
166+ tls_ctx_options .alpn_list = ['http/1.1' ] if use_websockets else ['x-amzn-mqtt-ca' ]
154167
155168 socket_options = awscrt .io .SocketOptions ()
156- socket_options .connect_timeout_ms = kwargs . get ( 'tcp_connect_timeout_ms' , 5000 )
169+ socket_options .connect_timeout_ms = _get ( kwargs , 'tcp_connect_timeout_ms' , 5000 )
157170 # These have been inconsistent between keepalive/keep_alive. Resolve both for now to ease transition.
158- socket_options .keep_alive = kwargs .get ('tcp_keep_alive' , kwargs .get ('tcp_keepalive' , False ))
159- socket_options .keep_alive_timeout_secs = kwargs .get (
160- 'tcp_keep_alive_timeout_secs' , kwargs .get (
161- 'tcp_keepalive_timeout_secs' , 0 ))
162- socket_options .keep_alive_interval_secs = kwargs .get (
163- 'tcp_keep_alive_interval_secs' , kwargs .get (
164- 'tcp_keepalive_interval_secs' , 0 ))
165- socket_options .keep_alive_max_probes = kwargs .get (
166- 'tcp_keep_alive_max_probes' , kwargs .get (
167- 'tcp_keepalive_max_probes' , 0 ))
168-
169- username = kwargs .get ('username' , '' )
170- if kwargs .get ('enable_metrics_collection' , True ):
171+ socket_options .keep_alive = \
172+ _get (kwargs , 'tcp_keep_alive' , _get (kwargs , 'tcp_keepalive' , False ))
173+
174+ socket_options .keep_alive_timeout_secs = \
175+ _get (kwargs , 'tcp_keep_alive_timeout_secs' , _get (kwargs , 'tcp_keepalive_timeout_secs' , 0 ))
176+
177+ socket_options .keep_alive_interval_secs = \
178+ _get (kwargs , 'tcp_keep_alive_interval_secs' , _get (kwargs , 'tcp_keepalive_interval_secs' , 0 ))
179+
180+ socket_options .keep_alive_max_probes = \
181+ _get (kwargs , 'tcp_keep_alive_max_probes' , _get (kwargs , 'tcp_keepalive_max_probes' , 0 ))
182+
183+ username = _get (kwargs , 'username' , '' )
184+ if _get (kwargs , 'enable_metrics_collection' , True ):
171185 username += _get_metrics_str ()
172186
173- client_bootstrap = kwargs . get ( 'client_bootstrap' )
187+ client_bootstrap = _get ( kwargs , 'client_bootstrap' )
174188 tls_ctx = awscrt .io .ClientTlsContext (tls_ctx_options )
175189 mqtt_client = awscrt .mqtt .Client (client_bootstrap , tls_ctx )
176190
177191 return awscrt .mqtt .Connection (
178192 client = mqtt_client ,
179- on_connection_interrupted = kwargs . get ( 'on_connection_interrupted' ),
180- on_connection_resumed = kwargs . get ( 'on_connection_resumed' ),
181- client_id = kwargs . get ( 'client_id' ),
182- host_name = kwargs . get ( 'endpoint' ),
193+ on_connection_interrupted = _get ( kwargs , 'on_connection_interrupted' ),
194+ on_connection_resumed = _get ( kwargs , 'on_connection_resumed' ),
195+ client_id = _get ( kwargs , 'client_id' ),
196+ host_name = _get ( kwargs , 'endpoint' ),
183197 port = port ,
184- clean_session = kwargs . get ( 'clean_session' , False ),
185- reconnect_min_timeout_secs = kwargs . get ( 'reconnect_min_timeout_secs' , 5 ),
186- reconnect_max_timeout_secs = kwargs . get ( 'reconnect_max_timeout_secs' , 60 ),
187- keep_alive_secs = kwargs . get ( 'keep_alive_secs' , 1200 ),
188- ping_timeout_ms = kwargs . get ( 'ping_timeout_ms' , 3000 ),
189- protocol_operation_timeout_ms = kwargs . get ( 'protocol_operation_timeout_ms' , 0 ),
190- will = kwargs . get ( 'will' ),
198+ clean_session = _get ( kwargs , 'clean_session' , False ),
199+ reconnect_min_timeout_secs = _get ( kwargs , 'reconnect_min_timeout_secs' , 5 ),
200+ reconnect_max_timeout_secs = _get ( kwargs , 'reconnect_max_timeout_secs' , 60 ),
201+ keep_alive_secs = _get ( kwargs , 'keep_alive_secs' , 1200 ),
202+ ping_timeout_ms = _get ( kwargs , 'ping_timeout_ms' , 3000 ),
203+ protocol_operation_timeout_ms = _get ( kwargs , 'protocol_operation_timeout_ms' , 0 ),
204+ will = _get ( kwargs , 'will' ),
191205 username = username ,
192- password = kwargs . get ( 'password' ),
206+ password = _get ( kwargs , 'password' ),
193207 socket_options = socket_options ,
194208 use_websockets = use_websockets ,
195209 websocket_handshake_transform = websocket_handshake_transform ,
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