class KafkaConsumer:
"""Defines the base kafka consumer class"""
def __init__(
self,
topic_name_pattern,
message_handler,
is_avro=True,
offset_earliest=False,
sleep_secs=1.0,
consume_timeout=0.1,
):
"""Creates a consumer object for asynchronous use"""
self.topic_name_pattern = topic_name_pattern
self.message_handler = message_handler
self.sleep_secs = sleep_secs
self.consume_timeout = consume_timeout
self.offset_earliest = offset_earliest
self.broker_properties = {
"bootstrap.servers": "PLAINTEXT://localhost:9094",
"group.id": "udacity",
"auto.offset.reset": "earliest" if offset_earliest else "latest"
}
if is_avro is True:
self.broker_properties["schema.registry.url"] = "http://localhost:8081"
self.consumer = AvroConsumer(self.broker_properties)
else:
self.consumer = Consumer(self.broker_properties)
self.consumer.subscribe([self.topic_name_pattern], on_assign=self.on_assign)
def on_assign(self, consumer, partitions):
"""Callback for when topic assignment takes place"""
logger.info("on_assign is incomplete - skipping")
for partition in partitions:
partition.offset = OFFSET_BEGINNING
logger.info("partitions assigned for %s", self.topic_name_pattern)
consumer.assign(partitions)
async def consume(self):
"""Asynchronously consumes data from kafka topic"""
while True:
num_results = 1
while num_results > 0:
num_results = self._consume()
await gen.sleep(self.sleep_secs)
def _consume(self):
"""Polls for a message. Returns 1 if a message was received, 0 otherwise"""
message = self.consumer.poll(1.0)
if message.error():
logger.warning(f"Error from consumer {message.error()}")
return 0
if message:
return 1
else:
return 0
logger.info("_consume is incomplete - skipping")
return 0
def close(self):
"""Cleans up any open kafka consumers"""
self.consumer.flush()
class KafkaConsumer:
def __init__(
self,
topic_name_pattern,
offset_earliest=False,
sleep_secs=1.0,
consume_timeout=0.1,
):
self.topic_name_pattern = topic_name_pattern
self.sleep_secs = sleep_secs
self.consume_timeout = consume_timeout
self.offset_earliest = offset_earliest
self.broker_properties = {
"bootstrap.servers": BROKER_URL,
'group.id': 'consumer',
"auto.offset.reset": "earliest" if offset_earliest else "latest"
}
self.consumer = Consumer(self.broker_properties)
self.consumer.subscribe(topics=[self.topic_name_pattern])
def on_assign(self, consumer, partitions):
"""Callback for when topic assignment takes place"""
# TODO: If the topic is configured to use `offset_earliest` set the partition offset to
# the beginning or earliest
logger.info("on_assign is incomplete - skipping")
for partition in partitions:
print(f"consume message {partition.key()}: {partition.value()}")
if self.offset_earliest == True:
print('OFFSET_BEGINNING')
partition.offset = OFFSET_BEGINNING
logger.info("partitions assigned for %s", self.topic_name_pattern)
consumer.assign(partitions)
async def consume(self):
"""Asynchronously consumes data from kafka topic"""
while True:
num_results = 1
while num_results > 0:
num_results = self._consume()
await gen.sleep(self.sleep_secs)
def _consume(self):
"""Polls for a message. Returns 1 if a message was received, 0 otherwise"""
#
#
message = self.consumer.poll(1)
if message is None:
print('0')
return 0
else:
print('1')
print(message.value())
return 1
#
#
logger.info("_consume is incomplete - skipping")
return 0
def close(self):
"""Cleans up any open kafka consumers"""
self.consumer.flush()
class KafkaConsumer:
"""Defines the base kafka consumer class"""
def __init__(
self,
topic_name_pattern,
message_handler,
is_avro=True,
offset_earliest=False,
sleep_secs=1.0,
consume_timeout=0.1,
):
"""Creates a consumer object for asynchronous use"""
self.topic_name_pattern = topic_name_pattern
self.message_handler = message_handler
self.sleep_secs = sleep_secs
self.consume_timeout = consume_timeout
self.offset_earliest = offset_earliest
#
#
# TODO: Configure the broker properties below. Make sure to reference the project README
# and use the Host URL for Kafka and Schema Registry!
#
#
self.broker_properties = {
#
# TODO
#
"bootstrap.servers": BROKER_URL,
"group.id": "0",
"schema.registry.url": SCHEMA_REGISTRY_URL
}
# TODO: Create the Consumer, using the appropriate type.
if is_avro is True:
self.consumer = AvroConsumer(config=self.broker_properties)
else:
self.consumer = Consumer({
"bootstrap.servers":
self.broker_properties["bootstrap.servers"],
"group.id":
self.broker_properties["group.id"]
})
#
#
# TODO: Configure the AvroConsumer and subscribe to the topics. Make sure to think about
# how the `on_assign` callback should be invoked.
#
#
self.consumer.subscribe([self.topic_name_pattern],
on_assign=self.on_assign)
def on_assign(self, consumer, partitions):
"""Callback for when topic assignment takes place"""
# TODO: If the topic is configured to use `offset_earliest` set the partition offset to
# the beginning or earliest
logger.info("on_assign is incomplete - skipping")
for partition in partitions:
if self.offset_earliest:
partition.offset = OFFSET_BEGINNING
#
#
# TODO
#
#
logger.info("partitions assigned for %s", self.topic_name_pattern)
consumer.assign(partitions)
async def consume(self):
"""Asynchronously consumes data from kafka topic"""
while True:
num_results = 1
while num_results > 0:
num_results = self._consume()
await gen.sleep(self.sleep_secs)
def _consume(self):
"""Polls for a message. Returns 1 if a message was received, 0 otherwise"""
# Poll Kafka for messages. Make sure to handle any errors or exceptions.
# Additionally, make sure you return 1 when a message is processed, and 0 when no message is retrieved.
try:
message = self.consumer.poll(self.consume_timeout)
except Exception as e:
logger.debug(f"Poll exception {self.topic_name_pattern}: {e}")
if message is None:
return 0
elif message.error() is not None:
logger.error(
f"Consumer error {self.topic_name_pattern}: {message.error()}")
else:
self.message_handler(message)
logger.info(f"Message consumed {message.key()}: {message.value()}")
return 1
def close(self):
"""Cleans up any open kafka consumers"""
#
#
# TODO: Cleanup the kafka consumer
#
#
if self.consumer is not None:
self.consumer.flush()