Q:

log4j warning after `homebrew install zookeeper`

I'm running Mac OS X 10.  I just did brew install zookeeper. 
Then I created /usr/local/etc/zookeeper/zoo.cfg based on /usr/local/etc/zookeeper/zoo_sample.cfg. 
Then zkServer start works just fine. 
But, when trying to connect to Zookeeper from Clojure, which uses the Zookeeper Java client, I get this error:
log4j:WARN No appenders could be found for logger (org.apache.zookeeper. ZooKeeper). 
log4j:WARN Please initialize the log4j system properly. 
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. 

My log4j.properties file:
log4j.rootCategory=WARN, zklog
log4j.appender.zklog = org.apache.log4j. FileAppender
log4j.appender.zklog. File = /usr/local/var/log/zookeeper/zookeeper.log
log4j.appender.zklog. Append = true
log4j.appender.zklog.layout = org.apache.log4j. PatternLayout
log4j.appender.zklog.layout. ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} %c{1} [%p] %m%n

So, my questions are:

What is a reasonable log4j configuration for my situation? 
What could homebrew do, out of the box, to prevent this warning from happening? 

A:

To be clear, there are two log4j.properties files involved.  One is created by Homebrew and gets written to /usr/local/etc/zookeeper/log4j.properties.  This file is not the cause of the error message above. 
The other log4j.properties file is particular to your (my) application.  So, to answer part 1 of the question, create a log4j.properties file on the classpath of the Clojure app, such as in the src directory. 
log4j.rootLogger=WARN, A1
log4j.logger.user=DEBUG
log4j.appender. A1=org.apache.log4j. ConsoleAppender
log4j.appender. A1.layout=org.apache.log4j. PatternLayout
log4j.appender. A1.layout. ConversionPattern=%d %-5p %c: %m%n

log4j.logger.org.apache.zookeeper=WARN

I built this by starting with https://github.com/clojure/tools.logging and adding the last line. 
To answer part 2, Homebrew does not and should not have anything to do with how a Clojure application sets up its logging.