Improve confluent-kafka instrumentation examples (#3369)

* Improve confluent-kafka instrumentation example

* Improve confluent-kafka tracer provider example

* Apply suggestions from code review

---------

Co-authored-by: Riccardo Magliocchetti <[email protected]>

Author: andremm

instrumentation/opentelemetry-instrumentation-confluent-kafka/src/opentelemetry/instrumentation/confluent_kafka/__init__.py

@@ -34,6 +34,9 @@
     # report a span of type consumer with the default settings
     consumer = Consumer(conf2)
 
+    def msg_process(msg):
+        print(msg)
+
     def basic_consume_loop(consumer, topics):
         try:
             consumer.subscribe(topics)
@@ -44,7 +47,7 @@ def basic_consume_loop(consumer, topics):
                 if msg.error():
                     if msg.error().code() == KafkaError._PARTITION_EOF:
                         # End of partition event
-                        sys.stderr.write(f"{msg.topic() [{msg.partition()}] reached end at offset {msg.offset()}}")
+                        sys.stderr.write(f"{msg.topic()} [{msg.partition()}] reached end at offset {msg.offset()}")
                     elif msg.error():
                         raise KafkaException(msg.error())
                 else:
@@ -53,7 +56,7 @@ def basic_consume_loop(consumer, topics):
             # Close down consumer to commit final offsets.
             consumer.close()
 
-    basic_consume_loop(consumer, "my-topic")
+    basic_consume_loop(consumer, ["my-topic"])
 
 The _instrument method accepts the following keyword args:
   tracer_provider (TracerProvider) - an optional tracer provider
@@ -72,14 +75,16 @@ def instrument_consumer(consumer: Consumer, tracer_provider=None)
 .. code:: python
 
     from opentelemetry.instrumentation.confluent_kafka import ConfluentKafkaInstrumentor
+    from opentelemetry.trace import get_tracer_provider
 
     from confluent_kafka import Producer, Consumer
 
     inst = ConfluentKafkaInstrumentor()
+    tracer_provider = get_tracer_provider()
 
-    p = confluent_kafka.Producer({'bootstrap.servers': 'localhost:29092'})
-    c = confluent_kafka.Consumer({
-        'bootstrap.servers': 'localhost:29092',
+    p = Producer({'bootstrap.servers': 'localhost:9092'})
+    c = Consumer({
+        'bootstrap.servers': 'localhost:9092',
         'group.id': 'mygroup',
         'auto.offset.reset': 'earliest'
     })