Allow KafkaClient to take in a list of brokers for bootstrapping

Author: mrtheb

README.md

@@ -30,7 +30,7 @@ from kafka.client import KafkaClient
 from kafka.consumer import SimpleConsumer
 from kafka.producer import SimpleProducer, KeyedProducer
 
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 
 # To send messages synchronously
 producer = SimpleProducer(kafka, "my-topic")
@@ -81,7 +81,7 @@ from kafka.client import KafkaClient
 from kafka.producer import KeyedProducer
 from kafka.partitioner import HashedPartitioner, RoundRobinPartitioner
 
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 
 # HashedPartitioner is default
 producer = KeyedProducer(kafka, "my-topic")
@@ -96,7 +96,7 @@ producer = KeyedProducer(kafka, "my-topic", partitioner=RoundRobinPartitioner)
 from kafka.client import KafkaClient
 from kafka.consumer import MultiProcessConsumer
 
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 
 # This will split the number of partitions among two processes
 consumer = MultiProcessConsumer(kafka, "my-group", "my-topic", num_procs=2)
@@ -116,7 +116,7 @@ for message in consumer.get_messages(count=5, block=True, timeout=4):
 
 ```python
 from kafka.client import KafkaClient
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 req = ProduceRequest(topic="my-topic", partition=1,
     messages=[KafkaProdocol.encode_message("some message")])
 resps = kafka.send_produce_request(payloads=[req], fail_on_error=True)

example.py

@@ -14,7 +14,7 @@ def consume_example(client):
         print(message)
 
 def main():
-    client = KafkaClient("localhost", 9092)
+    client = KafkaClient("localhost:9092")
     produce_example(client)
     consume_example(client)
 

kafka/NOTES.md

@@ -18,7 +18,7 @@ There are a few levels of abstraction:
 
 # Possible API
 
-    client = KafkaClient("localhost", 9092)
+    client = KafkaClient("localhost:9092")
 
     producer = KafkaProducer(client, "topic")
     producer.send_string("hello")

kafka/client.py

@@ -8,7 +8,7 @@
 
 from kafka.common import ErrorMapping, TopicAndPartition
 from kafka.common import ConnectionError, FailedPayloadsException
-from kafka.conn import KafkaConnection
+from kafka.conn import collect_hosts, KafkaConnection
 from kafka.protocol import KafkaProtocol
 
 log = logging.getLogger("kafka")
@@ -19,13 +19,15 @@ class KafkaClient(object):
     CLIENT_ID = "kafka-python"
     ID_GEN = count()
 
-    def __init__(self, host, port, bufsize=4096, client_id=CLIENT_ID):
+    def __init__(self, hosts, bufsize=4096, client_id=CLIENT_ID):
         # We need one connection to bootstrap
         self.bufsize = bufsize
         self.client_id = client_id
-        self.conns = {               # (host, port) -> KafkaConnection
-            (host, port): KafkaConnection(host, port, bufsize)
-        }
+
+        self.hosts = collect_hosts(hosts)
+
+        # create connections only when we need them
+        self.conns = {}
         self.brokers = {}            # broker_id -> BrokerMetadata
         self.topics_to_brokers = {}  # topic_id -> broker_id
         self.topic_partitions = defaultdict(list)  # topic_id -> [0, 1, 2, ...]
@@ -35,15 +37,19 @@ def __init__(self, host, port, bufsize=4096, client_id=CLIENT_ID):
     #   Private API  #
     ##################
 
+    def _get_conn(self, host, port):
+        "Get or create a connection to a broker using host and port"
+
+        host_key = (host, port)
+        if host_key not in self.conns:
+            self.conns[host_key] = KafkaConnection(host, port, self.bufsize)
+
+        return self.conns[host_key]
+
     def _get_conn_for_broker(self, broker):
-        """
-        Get or create a connection to a broker
-        """
-        if (broker.host, broker.port) not in self.conns:
-            self.conns[(broker.host, broker.port)] = \
-                KafkaConnection(broker.host, broker.port, self.bufsize)
+        "Get or create a connection to a broker"
 
-        return self.conns[(broker.host, broker.port)]
+        return self._get_conn(broker.host, broker.port)
 
     def _get_leader_for_partition(self, topic, partition):
         key = TopicAndPartition(topic, partition)
@@ -108,7 +114,8 @@ def _send_broker_unaware_request(self, requestId, request):
         Attempt to send a broker-agnostic request to one of the available
         brokers. Keep trying until you succeed.
         """
-        for conn in self.conns.values():
+        for (host, port) in self.hosts:
+            conn = self._get_conn(host, port)
             try:
                 conn.send(requestId, request)
                 response = conn.recv(requestId)
@@ -174,7 +181,7 @@ def _send_broker_aware_request(self, payloads, encoder_fn, decoder_fn):
             except ConnectionError, e:  # ignore BufferUnderflow for now
                 log.warning("Could not send request [%s] to server %s: %s" % (request, conn, e))
                 failed_payloads += payloads
-                self.topics_to_brokers = {} # reset metadata
+                self.topics_to_brokers = {}  # reset metadata
                 continue
 
             for response in decoder_fn(response):

kafka/conn.py

@@ -2,6 +2,7 @@
 import logging
 import socket
 import struct
+from random import shuffle
 from threading import local
 
 from kafka.common import BufferUnderflowError
@@ -10,6 +11,26 @@
 log = logging.getLogger("kafka")
 
 
+def collect_hosts(hosts, randomize=True):
+    """
+    Collects a comma-separated set of hosts (host:port) and optionnaly
+    randomize the returned list.
+    """
+
+    result = []
+    for host_port in hosts.split(","):
+
+        res = host_port.split(':')
+        host = res[0]
+        port = int(res[1]) if len(res) > 1 else 9092
+        result.append((host.strip(), port))
+
+    if randomize:
+        shuffle(result)
+
+    return result
+
+
 class KafkaConnection(local):
     """
     A socket connection to a single Kafka broker
@@ -19,14 +40,14 @@ class KafkaConnection(local):
     we can do something in here to facilitate multiplexed requests/responses
     since the Kafka API includes a correlation id.
     """
-    def __init__(self, host, port, bufsize=4096):
+    def __init__(self, host, port, bufsize=4096, timeout=10):
         super(KafkaConnection, self).__init__()
         self.host = host
         self.port = port
         self.bufsize = bufsize
-        self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        self._sock.connect((host, port))
-        self._sock.settimeout(10)
+        self.timeout = timeout
+
+        self._sock = socket.create_connection((host, port), timeout=timeout)
         self._dirty = False
 
     def __str__(self):
@@ -125,7 +146,5 @@ def reinit(self):
         Re-initialize the socket connection
         """
         self.close()
-        self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        self._sock.connect((self.host, self.port))
-        self._sock.settimeout(10)
+        self._sock = socket.create_connection((self.host, self.port), timeout=self.timeout)
         self._dirty = False

setup.py

@@ -1,11 +1,12 @@
-import os.path
 import sys
 
 from setuptools import setup, Command
 
 
 class Tox(Command):
+
     user_options = []
+
     def initialize_options(self):
         pass
 
@@ -21,7 +22,7 @@ def run(self):
     name="kafka-python",
     version="0.8.1-1",
 
-    install_requires=["distribute", "tox"],
+    install_requires=["distribute", "tox", "mock"],
     tests_require=["tox"],
     cmdclass={"test": Tox},
 

test/test_integration.py

@@ -16,7 +16,7 @@ class TestKafkaClient(unittest.TestCase):
     def setUpClass(cls):  # noqa
         cls.zk = ZookeeperFixture.instance()
         cls.server = KafkaFixture.instance(0, cls.zk.host, cls.zk.port)
-        cls.client = KafkaClient(cls.server.host, cls.server.port)
+        cls.client = KafkaClient('%s:%d' % (cls.server.host, cls.server.port))
 
     @classmethod
     def tearDownClass(cls):  # noqa
@@ -554,7 +554,7 @@ def setUpClass(cls):
         cls.zk = ZookeeperFixture.instance()
         cls.server1 = KafkaFixture.instance(0, cls.zk.host, cls.zk.port)
         cls.server2 = KafkaFixture.instance(1, cls.zk.host, cls.zk.port)
-        cls.client = KafkaClient(cls.server2.host, cls.server2.port, bufsize=8192)
+        cls.client = KafkaClient('%s:%d' % (cls.server2.host, cls.server2.port), bufsize=8192)
 
     @classmethod
     def tearDownClass(cls):  # noqa
@@ -770,20 +770,23 @@ def test_large_messages(self):
             self.assertEquals(all_messages[i], message.message)
         self.assertEquals(i, 19)
 
+
 class TestFailover(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
 
         zk_chroot = random_string(10)
-        replicas   = 2
+        replicas = 2
         partitions = 2
 
         # mini zookeeper, 2 kafka brokers
-        cls.zk      = ZookeeperFixture.instance()
-        kk_args     = [cls.zk.host, cls.zk.port, zk_chroot, replicas, partitions]
+        cls.zk = ZookeeperFixture.instance()
+        kk_args = [cls.zk.host, cls.zk.port, zk_chroot, replicas, partitions]
         cls.brokers = [KafkaFixture.instance(i, *kk_args) for i in range(replicas)]
-        cls.client  = KafkaClient(cls.brokers[0].host, cls.brokers[0].port)
+
+        hosts = ','.join(['%s:%d' % (b.host, b.port) for b in cls.brokers])
+        cls.client = KafkaClient(hosts)
 
     @classmethod
     def tearDownClass(cls):
@@ -858,17 +861,19 @@ def _send_random_messages(self, producer, n):
             resp = producer.send_messages(random_string(10))
             if len(resp) > 0:
                 self.assertEquals(resp[0].error, 0)
-        time.sleep(1) # give it some time
+        time.sleep(1)  # give it some time
 
     def _kill_leader(self, topic, partition):
         leader = self.client.topics_to_brokers[TopicAndPartition(topic, partition)]
         broker = self.brokers[leader.nodeId]
         broker.close()
-        time.sleep(1) # give it some time
+        time.sleep(1)  # give it some time
         return broker
 
     def _count_messages(self, group, topic):
-        client   = KafkaClient(self.brokers[0].host, self.brokers[0].port)
+
+        hosts = '%s:%d' % (self.brokers[0].host, self.brokers[0].port)
+        client = KafkaClient(hosts)
         consumer = SimpleConsumer(client, group, topic, auto_commit=False)
         all_messages = []
         for message in consumer: