Add error_cb to confluent_cloud.py example

edenhill · edenhill · commit c257758bb524 · 2021-04-21T17:09:37.000+02:00
diff --git a/examples/confluent_cloud.py b/examples/confluent_cloud.py
@@ -48,42 +48,76 @@
 
 import uuid
 
-from confluent_kafka import Producer, Consumer
+from confluent_kafka import Producer, Consumer, KafkaError, KafkaException
 
 
+def error_cb(err):
+    """ The error callback is used for generic client errors. These
+        errors are generally to be considered informational as the client will
+        automatically try to recover from all errors, and no extra action
+        is typically required by the application.
+        For this example however, we terminate the application if the client
+        is unable to connect to any broker (_ALL_BROKERS_DOWN) and on
+        authentication errors (_AUTHENTICATION). """
+
+    print("Client error: {}".format(err))
+    if err.code() == KafkaError._ALL_BROKERS_DOWN or \
+       err.code() == KafkaError._AUTHENTICATION:
+        # Any exception raised from this callback will be re-raised from the
+        # triggering flush() or poll() call.
+        raise KafkaException(err)
+
+
+# Create producer
 p = Producer({
     'bootstrap.servers': '<ccloud bootstrap servers>',
     'sasl.mechanism': 'PLAIN',
     'security.protocol': 'SASL_SSL',
     'sasl.username': '<ccloud key>',
-    'sasl.password': '<ccloud secret>'
+    'sasl.password': '<ccloud secret>',
+    'error_cb': error_cb,
 })
 
 
 def acked(err, msg):
     """Delivery report callback called (from flush()) on successful or failed delivery of the message."""
     if err is not None:
-        print("failed to deliver message: {}".format(err.str()))
+        print('Failed to deliver message: {}'.format(err.str()))
     else:
-        print("produced to: {} [{}] @ {}".format(msg.topic(), msg.partition(), msg.offset()))
+        print('Produced to: {} [{}] @ {}'.format(msg.topic(), msg.partition(), msg.offset()))
+
 
+for n in range(0, 10):
+    # Produce message: this is an asynchronous operation.
+    # Upon successful or permanently failed delivery to the broker the
+    # callback will be called to propagate the produce result.
+    # The delivery callback is triggered from poll() or flush().
+    # For long running
+    # produce loops it is recommended to call poll() to serve these
+    # delivery report callbacks.
+    p.produce('python-test-topic', value='python test value nr {}'.format(n),
+              callback=acked)
 
-p.produce('python-test-topic', value='python test value', callback=acked)
+    # Trigger delivery report callbacks from previous produce calls.
+    p.poll(0)
 
 # flush() is typically called when the producer is done sending messages to wait
 # for outstanding messages to be transmitted to the broker and delivery report
 # callbacks to get called. For continous producing you should call p.poll(0)
 # after each produce() call to trigger delivery report callbacks.
 p.flush(10)
 
+
+# Create consumer
 c = Consumer({
     'bootstrap.servers': '<ccloud bootstrap servers>',
     'sasl.mechanism': 'PLAIN',
     'security.protocol': 'SASL_SSL',
     'sasl.username': '<ccloud key>',
     'sasl.password': '<ccloud secret>',
     'group.id': str(uuid.uuid1()),  # this will create a new consumer group on each invocation.
-    'auto.offset.reset': 'earliest'
+    'auto.offset.reset': 'earliest',
+    'error_cb': error_cb,
 })
 
 c.subscribe(['python-test-topic'])
@@ -98,10 +132,10 @@ def acked(err, msg):
             continue
         if msg.error():
             # Errors are typically temporary, print error and continue.
-            print("Consumer error: {}".format(msg.error()))
+            print('Consumer error: {}'.format(msg.error()))
             continue
 
-        print('consumed: {}'.format(msg.value()))
+        print('Consumed: {}'.format(msg.value()))
 
 except KeyboardInterrupt:
     pass
