I have a production site configured with Apache2 forwarding requests to Tomcat using mod_jk. I wanted to mimic this configuration on my desktop environment, but was not able to get it to work locally on my Mac. I ended up using mod_proxy locally instead. This is the ordeal I went through…

I grabbed a binary for Mac OSX (x86) from the Tomcat Connectors site, renamed it to mod_jk.so, and dropped it in the directory with the other modules. I made the necessary changes and additions to the Apache config files. Unfortunately, when I started Apache, I received the following error:

no suitable image found.  Did find: /usr/libexec/apache2/mod_jk.so:
mach-o, but wrong architecture

Googling the error helped me realize that I wasn’t alone with my issue and I figured out that I needed to build mod_jk from source, passing in some special flags to the build:

./configure CFLAGS='-arch x86_64' APXSLDFLAGS='-arch x86_64'
-with-apxs=/usr/sbin/apxs

This was great, but the next step (i.e., “make”), kept failing for me:

jk_global.h:66:21: error: apr_lib.h: No such file or directory
jk_global.h:67:25: error: apr_strings.h: No such file or directory
make[1]: *** [jk_ajp12_worker.lo] Error 1
make: *** [all-recursive] Error 1

I found lots of other pages explaining further variations of the same basic premise that I needed to build from source:

• http://de-co-de.blogspot.com/2008/04/if-you-install-modjk.html
• http://egopoly.com/2007/10/29/how-to-install-tomcat-mod_jk-on-mac-os-x-leopard/
• http://blog.lo-fi.net/2007/10/leopard-for-web-developer-installing.html

I followed all of these instructions, but still had no luck. Then I tried going down the DarwinPorts path:

• http://mod_jk.darwinports.com/

But I didn’t get anywhere with this:

mike$ sudo port install mod_jk
...
Configuring APR library
Platform: i386-apple-darwin9.4.0
checking for working mkdir -p... yes
APR Version: 1.3.2
checking for chosen layout... apr
checking for gcc... /usr/bin/gcc-4.0
checking for C compiler default output file name...
configure: error: C compiler cannot create executables
See `config.log' for more details.

I came to suspect that I might require an install of Apple’s Xcode to get any of these solutions to work. So I started downloading it. As I was waiting for the download to complete, I started looking at mod_proxy as an alternative to mod_jk. Using mod_proxy wouldn’t accomplish my goal of mirroring the production configuration and I wasn’t sure if it could handle sticky sessions, but I didn’t need that at this point. So I gave it a whirl, fought with it a little bit, and eventually was able to configure a solution before I got anywhere with Xcode:

In Apache’s httpd.conf:

<Proxy balancer://myCluster>
   BalancerMember ajp://dev.milestoneinc.com:8010 route=node1
</Proxy>

ProxyPass /blogs !
ProxyPass /balancer-manager !
ProxyPass / balancer://myCluster/ stickysession=JSESSIONID

<Location /balancer-manager>
	SetHandler balancer-manager
</Location>

In Tomcat’s server.xml:

<Engine defaultHost="localhost" jvmRoute="node1" name="Catalina">

More information regarding mod_proxy and load-balancing/session-affinity:

• http://www.darkcoding.net/2006/02/page/2/
• http://wiki.apache.org/cocoon/LoadBalancingWithModProxy
• http://www.nabble.com/mod_ajp-and-Load-Balancing-Issue-td18283072.html
• http://www.theserverside.com/tt/kno…er.tss?l=LoadBalancingTomcatApache
• http://www.markround.com/archi…ncing-with-PHP-sticky-sessions.html

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