PHP extension for interfacing with Apache ZooKeeper Formula was removed
Last versions were
php53-zookeeper requires the following formulae to be installed:
autoconf 2.69 Automatic configure script builder
zookeeper 3.4.10 Centralized server for distributed coordination of services

Recent formula history

Mike McQuaid Deprecate tap.
Andreas Braun Add description for zookeeper formula
Andy Blyler php53-zookeeper: convert from sha1 to sha256
Andy Blyler fix style issues
Andy Blyler Update URLs to use HTTPS

Formula code at GitHub