mapr-streams-python

MapR Streams Python Client


License
Apache-2.0
Install
pip install mapr-streams-python==0.11.0

Documentation

Confluent's Apache Kafka client for Python

Confluent's Kafka client for Python wraps the librdkafka C library, providing full Kafka protocol support with great performance and reliability.

The Python bindings provides a high-level Producer and Consumer with support for the balanced consumer groups of Apache Kafka 0.9.

See the API documentation for more info.

License: Apache License v2.0

Usage

Producer:

from confluent_kafka import Producer

p = Producer({'bootstrap.servers': 'mybroker,mybroker2'})
for data in some_data_source:
    p.produce('mytopic', data.encode('utf-8'))
p.flush()

High-level Consumer:

from confluent_kafka import Consumer, KafkaError

c = Consumer({'bootstrap.servers': 'mybroker', 'group.id': 'mygroup',
              'default.topic.config': {'auto.offset.reset': 'smallest'}})
c.subscribe(['mytopic'])
running = True
while running:
    msg = c.poll()
    if not msg.error():
        print('Received message: %s' % msg.value().decode('utf-8'))
    elif msg.error().code() != KafkaError._PARTITION_EOF:
        print(msg.error())
        running = False
c.close()

AvroProducer

from confluent_kafka import avro 
from confluent_kafka.avro import AvroProducer

value_schema = avro.load('ValueSchema.avsc')
key_schema = avro.load('KeySchema.avsc')
value = {"name": "Value"}
key = {"name": "Key"}

avroProducer = AvroProducer({'bootstrap.servers': 'mybroker,mybroker2', 'schema.registry.url': 'http://schem_registry_host:port'}, default_key_schema=key_schema, default_value_schema=value_schema)
avroProducer.produce(topic='my_topic', value=value, key=key)

AvroConsumer

from confluent_kafka import KafkaError
from confluent_kafka.avro import AvroConsumer
from confluent_kafka.avro.serializer import SerializerError

c = AvroConsumer({'bootstrap.servers': 'mybroker,mybroker2', 'group.id': 'groupid', 'schema.registry.url': 'http://127.0.0.1:8081'})
c.subscribe(['my_topic'])
running = True
while running:
    try:
        msg = c.poll(10)
        if msg:
            if not msg.error():
                print(msg.value())
            elif msg.error().code() != KafkaError._PARTITION_EOF:
                print(msg.error())
                running = False
    except SerializerError as e:
        print("Message deserialization failed for %s: %s" % (msg, e))
        running = False
        
c.close()

See examples for more examples.

Broker compatibility

The Python client (as well as the underlying C library librdkafka) supports all broker versions >= 0.8. But due to the nature of the Kafka protocol in broker versions 0.8 and 0.9 it is not safe for a client to assume what protocol version is actually supported by the broker, thus you will need to hint the Python client what protocol version it may use. This is done through two configuration settings:

  • broker.version.fallback=YOUR_BROKER_VERSION (default 0.9.0.1)
  • api.version.request=true|false (default false)

When using a Kafka 0.10 broker or later you only need to set api.version.request=true. If you use Kafka broker 0.9 or 0.8 you should leave api.version.request=false (default) and set broker.version.fallback to your broker version, e.g broker.version.fallback=0.9.0.1.

More info here: https://github.com/edenhill/librdkafka/wiki/Broker-version-compatibility

Prerequisites

Install

Install from PyPi:

$ pip install confluent-kafka

# for AvroProducer or AvroConsumer
$ pip install confluent-kafka[avro]

Install from source / tarball:

$ pip install .

# for AvroProducer or AvroConsumer
$ pip install .[avro]

Build

$ python setup.py build

If librdkafka is installed in a non-standard location provide the include and library directories with:

$ C_INCLUDE_PATH=/path/to/include LIBRARY_PATH=/path/to/lib python setup.py ...

Tests

Run unit-tests:

In order to run full test suite, simply execute:

$ tox -r

NOTE: Requires tox (please install with pip install tox), several supported versions of Python on your path, and librdkafka installed into tmp-build.

Run integration tests:

To run the integration tests, uncomment the following line from tox.ini and add the paths to your Kafka and Confluent Schema Registry instances. If no Schema Registry path is provided then no AVRO tests will by run. You can also run the integration tests outside of tox by running this command from the source root.

examples/integration_test.py <kafka-broker> [<test-topic>] [<schema-registry>]

WARNING: These tests require an active Kafka cluster and will create new topics.

Generate documentation

Install sphinx and sphinx_rtd_theme packages and then:

$ make docs

or:

$ python setup.py build_sphinx

Documentation will be generated in docs/_build/.