Why can't I connect to Kafka/Zookeeper? (In a Docker)
<p>I'm running Kafka (0.10.0.0) in a Docker on a Mac (w/docker-machine).  I derived my Dockerfile from Spotify's, which means Kafka and Zookeeper run in the same image.</p>

<p>My instance starts cleanly and poking around inside it <em>appears</em> everything is normal/OK.</p>

<p>Docker maps ports 2181 and 9092 to high-ports 32822 and 32820 in this case.  From outside my running Kafka Docker I am able to successfully telnet 192.168.99.100 32822 (where 192.168.99.100 is the IP of my docker-machine).  From there I can issue a zookeeper command and get expected output.</p>

<p>It all seems so encouraging, but... I then try this code:</p>

<pre><code>val numPartitions = 4
val replicationFactor = 1
val topicConfig = new java.util.Properties

// zookeeper = "192.168.99.100:32822"
val zkClient = ZkUtils(zookeeper, 10000, 10000, false)
try {
  AdminUtils.createTopic(zkClient, topic, numPartitions, replicationFactor, topicConfig)
} catch {
  case k: kafka.common.TopicExistsException =&gt; // do nothing...topic exists
}
zkClient.close()
</code></pre>

<p>This produces this error output:</p>

<pre><code>DEBUG ZkConnection - Creating new ZookKeeper instance to connect to 192.168.99.100:32822.
INFO  ZkEventThread - Starting ZkClient event thread.
INFO  ZooKeeper - Client environment:zookeeper.version=3.4.6-1569965, built on 02/20/2014 09:09 GMT
INFO  ZooKeeper - Client environment:host.name=172.25.42.82
INFO  ZooKeeper - Client environment:java.version=1.8.0_60
INFO  ZooKeeper - Client environment:java.vendor=Oracle Corporation
INFO  ZooKeeper - Client environment:java.home=/Library/Java/JavaVirtualMachines/jdk1.8.0_60.jdk/Contents/Home/jre
INFO  ZooKeeper - Client environment:java.class.path=/usr/local/Cellar/sbt/0.13.11/libexec/sbt-launch.jar
INFO  ZooKeeper - Client environment:java.library.path=/Users/wmy965/Library/Java/Extensions:/Library/Java/Extensions:/Network/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:.
INFO  ZooKeeper - Client environment:java.io.tmpdir=/var/folders/ph/ccz4n1qs62n0bn8mqdg94gswt1jlwk/T/
INFO  ZooKeeper - Client environment:java.compiler=&lt;NA&gt;
INFO  ZooKeeper - Client environment:os.name=Mac OS X
INFO  ZooKeeper - Client environment:os.arch=x86_64
INFO  ZooKeeper - Client environment:os.version=10.11.5
INFO  ZooKeeper - Client environment:user.name=wmy965
INFO  ZooKeeper - Client environment:user.home=/Users/wmy965
INFO  ZooKeeper - Client environment:user.dir=/Users/wmy965/git/LateKafka
INFO  ZooKeeper - Initiating client connection, connectString=192.168.99.100:32822 sessionTimeout=10000 watcher=org.I0Itec.zkclient.ZkClient@55397e3
DEBUG ClientCnxn - zookeeper.disableAutoWatchReset is false
DEBUG ZkClient - Awaiting connection to Zookeeper server
INFO  ZkClient - Waiting for keeper state SyncConnected
INFO  ClientCnxn - Opening socket connection to server 192.168.99.100/192.168.99.100:32822. Will not attempt to authenticate using SASL (unknown error)
WARN  ClientCnxn - Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect
java.net.ConnectException: Connection refused
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
    at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1081)
DEBUG ClientCnxnSocketNIO - Ignoring exception during shutdown input
java.nio.channels.ClosedChannelException
    at sun.nio.ch.SocketChannelImpl.shutdownInput(SocketChannelImpl.java:780)
    at sun.nio.ch.SocketAdaptor.shutdownInput(SocketAdaptor.java:399)
    at org.apache.zookeeper.ClientCnxnSocketNIO.cleanup(ClientCnxnSocketNIO.java:200)
    at org.apache.zookeeper.ClientCnxn$SendThread.cleanup(ClientCnxn.java:1185)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1110)
DEBUG ClientCnxnSocketNIO - Ignoring exception during shutdown output
java.nio.channels.ClosedChannelException
    at sun.nio.ch.SocketChannelImpl.shutdownOutput(SocketChannelImpl.java:797)
    at sun.nio.ch.SocketAdaptor.shutdownOutput(SocketAdaptor.java:407)
    at org.apache.zookeeper.ClientCnxnSocketNIO.cleanup(ClientCnxnSocketNIO.java:207)
    at org.apache.zookeeper.ClientCnxn$SendThread.cleanup(ClientCnxn.java:1185)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1110)
INFO  ClientCnxn - Opening socket connection to server 192.168.99.100/192.168.99.100:32822. Will not attempt to authenticate using SASL (unknown error)
INFO  ClientCnxn - Socket connection established to 192.168.99.100/192.168.99.100:32822, initiating session
DEBUG ClientCnxn - Session establishment request sent on 192.168.99.100/192.168.99.100:32822
INFO  ClientCnxn - Session establishment complete on server 192.168.99.100/192.168.99.100:32822, sessionid = 0x155225c51720000, negotiated timeout = 10000
DEBUG ZkClient - Received event: WatchedEvent state:SyncConnected type:None path:null
INFO  ZkClient - zookeeper state changed (SyncConnected)
DEBUG ZkClient - Leaving process event
DEBUG ZkClient - State is SyncConnected
DEBUG ClientCnxn - Reading reply sessionid:0x155225c51720000, packet:: clientPath:null serverPath:null finished:false header:: 1,8  replyHeader:: 1,1,-101  request:: '/brokers/ids,F  response:: v{}
</code></pre>

<p>It looks like I can't connect (presumably to zookeeper).  Why not?</p>