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import logging |
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from confluent_kafka import Consumer, KafkaError, KafkaException, TopicPartition |
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from kafka_influxdb.encoder.errors import EncoderError |
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from kafka_influxdb.reader.reader import ReaderAbstract |
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class Reader(ReaderAbstract): |
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""" |
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A high-performance Kafka consumer based on confluent-kafka, which uses librdkafka internally. |
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See: https://github.com/confluentinc/confluent-kafka-python |
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""" |
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def _subscribe(self): |
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""" |
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Subscribe to Kafka topics. |
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A workaround for missing Zookeeper support in confluent-python is required here. |
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Automatic partition rebalancing is not working with Kafka Versions < 0.9.0. |
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Therefore we manually assign the partitions to the consumer for legacy Kafka versions. |
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""" |
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if self.broker_version < self.KAFKA_VERSION_ZOOKEEPER_OPTIONAL: |
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self.consumer.assign([TopicPartition(self.topic, p) for p in range(0, 10)]) |
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else: |
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self.consumer.subscribe([self.topic]) |
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def _setup_connection(self): |
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""" |
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Confluent-Kafka configuration |
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""" |
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# TODO: Test async commit handling (self.consumer.commit(async=False)) |
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connection = { |
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'bootstrap.servers': self.host + ":" + self.port, |
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'group.id': self.group, |
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'offset.store.method': 'broker', |
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'default.topic.config': { |
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# TODO: Make this configurable |
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'auto.offset.reset': 'largest' # smallest |
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} |
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} |
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# Add additional flag based on the Kafka version. |
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if self.broker_version < self.KAFKA_VERSION_ZOOKEEPER_OPTIONAL: |
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connection['broker.version.fallback'] = self.broker_version |
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return connection |
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def _connect(self): |
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""" |
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Connect to Kafka and subscribe to the topic |
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""" |
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connection = self._setup_connection() |
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logging.info("Connecting to Kafka with the following settings:\n %s...", connection) |
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self.consumer = Consumer(**connection) |
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self._subscribe() |
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def _handle_read(self): |
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""" |
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Read messages from Kafka. |
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""" |
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while True: |
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msg = self.consumer.poll(timeout=1.0) |
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if __debug__: |
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logging.debug(msg) |
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if msg is None: |
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continue |
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if msg.error(): |
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self._handle_error(msg) |
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else: |
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# Proper message |
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if __debug__: |
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logging.debug('%s [%d] at offset %d with key %s:\n', |
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msg.topic(), msg.partition(), msg.offset(), str(msg.key())) |
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yield msg.value().rstrip() |
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@staticmethod |
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def _handle_error(msg): |
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if not msg.error(): |
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return |
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# Error or event |
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if msg.error().code() == KafkaError._PARTITION_EOF: |
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# End of partition event |
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logging.info('%s [%d] reached end at offset %d with key %s\n', |
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msg.topic(), msg.partition(), msg.offset(), str(msg.key())) |
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else: |
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raise EncoderError(msg.error()) |
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mre /
kafka-influxdb
