$brew install zookeeper
==> Downloading https://homebrew.bintray.com/bottles/zookeeper-3.4.6_1.mavericks.bottle.2.tar.gz
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==> Pouring zookeeper-3.4.6_1.mavericks.bottle.2.tar.gz
==> Caveats
To have launchd start zookeeper at login:
  ln -sfv /usr/local/opt/zookeeper/*.plist ~/Library/LaunchAgents
Then to load zookeeper now:
  launchctl load ~/Library/LaunchAgents/homebrew.mxcl.zookeeper.plist
Or, if you don't want/need launchctl, you can just run:
  zkServer start
==> Summary

# The number of milliseconds of each tick
tickTime=2000
# The number of ticks that the initial
# synchronization phase can take
initLimit=10
# The number of ticks that can pass between
# sending a request and getting an acknowledgement
syncLimit=5
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just
# example sakes.
dataDir=/usr/local/var/run/zookeeper/data
# the port at which the clients will connect
clientPort=2181
# the maximum number of client connections.
# increase this if you need to handle more clients
#maxClientCnxns=60
#
# Be sure to read the maintenance section of the
# administrator guide before turning on autopurge.
#
# http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance
#
# The number of snapshots to retain in dataDir
#autopurge.snapRetainCount=3
# Purge task interval in hours
# Set to "0" to disable auto purge feature
#autopurge.purgeInterval=1