CF8/JRun4 Cluster for Load Balancing

The article at http://www.adobe.com/go/1e8e9170 is specific to configuring two or more cluster nodes that reside on separate networks, e.g. 10.0.1.0/24 and 10.0.2.0/24. (The article doesn't state it, but you can only use unicast peers if your cluster nodes host a single instance of JRun or multiple instances of JRun in the same cluster domain. When performing unicast discovery, JRun looks for all Jini groups and not just the cluster group.)

Anyhow, that's not your problem. The simplest solution is you haven't enabled the jrun.servlet.jrpp.JRunProxyService service. I'm most familiar with the Windows version of JRun, but I'm assuming the directory structure is similar across platforms. In <jrun_root>/servers/<name>/SERVER-INF/jrun.xml, set the deactivated attribute of the jrun.servlet.jrpp.JRunProxyService service to false and restart JRun. You should now see JRun listening on the appropriate port. (The default for the first manually created instance is 51000.) You can limit the proxy service to a single interface using the interface attribute.

If you have enabled the proxy service, verify your security settings in <jrun_root>/lib/security.properties. It's usually best to limit access to specific hosts. Comment out the jrun.subnet.restriction parameter and set the jrun.trusted.hosts to the IP address of your web server, e.g. 10.1.0.54.

Forcing all JRun processes/services to listen on a single interface isn't difficult, but it does require modifying quite a few configuration files by hand. If you need assistance with that, I can elaborate.

Configuring the JRun module under Apache is pretty straightforward. If you're not using virtual hosts, it's very simple. If you are using virtual hosts, it's still simple, but your JRun configuration can be virtual host-specific.

On your Apache server, you'll want to create a directory structure for the JRun module. I'll assume /opt/jrun/lib/wsconfig/1, but you can use anything you want. Once the directory structure is created, extract the appropriate JRun module from wsconfig.jar to the new directory. You're most likely interested in the Apache 2.0 module, wsconfig.jar/connectors/apache/intel-linux/prebuilt/mod_jrun20.so. Let's assume you've extracted the module to /opt/jrun/lib/wsconfig/1/mod_jrun20.so. Your Apache service account should have read, write, and execute permissions on the /opt/jrun/lib/wsconfig/1 directory.

The JRun module configuration is normally appended to your current httpd.conf file by wsconfig. Here's a sample configuration:

LoadModule jrun_module "/opt/jrun/lib/wsconfig/1/mod_jrun20.so"

<IfModule mod_jrun20.c>
JRunConfig Verbose false
JRunConfig Apialloc false
JRunConfig Ssl false
JRunConfig Ignoresuffixmap false
JRunConfig Serverstore "/opt/jrun/lib/wsconfig/1/jrunserver.store"
JRunConfig Bootstrap 10.1.0.70:51000
#JRunConfig Errorurl <optionally redirect to this URL on errors>
#JRunConfig ProxyRetryInterval 600
#JRunConfig ConnectTimeout 30
#JRunConfig RecvTimeout 30
#JRunConfig SendTimeout 30

AddHandler jrun-handler .jsp .jws .cfm .cfml .cfc .cfr .cfswf
</IfModule>

You may also want to update your DirectoryIndex directive with an appropriate index page, e.g. index.cfm.

After the first request to a page handled by the JRun module is received, the module will query the boostrap server, 10.1.0.70:51000, for a list of cluster peers. If you've configured your cluster correctly, a line similar to following will be written to /opt/jrun/lib/wsconfig/1/jrunserver.store:

proxyservers=10.1.0.70:51000;10.1.0.71:51000

You can create/edit this file manually as well. Unfortunately, the bootstrap option only accepts one server. If your bootstrap server is down, the JRun module will use the values in jrunserver.store directly, if the file exists.

Here's a complete list of JRun module options:

metrics *
debugger *
ssl *
verbose
traceflags
serverstore
bootstrap
errorurl
apialloc
ignoresuffixmap
proxyretryinterval
connecttimeout
recvtimeout
sendtimeout
sslcalist

Options flagged with an asterisk can only be configured at the Apache server level. All other options can be configured at the server level and/or the virtual host level. The usage of these options is in the JRun documentation, and the JRun module source code is included in wsconfig.jar. Keep in mind that versions of the JRun module shipped prior to ColdFusion 8 were coded to assign the connecttimeout and sendtimeout options to the socket connection timeout. Whichever option appeared last in your configuration ended up as the final value. This has been fixed in ColdFusion 8 and presumably the next release of the JRun updater.

I think that's a good start. If you need more information or can't find what you need in the JRun or ColdFusion documentation, let me know.

If you're looking for resiliency, I highly recommend expanding your configuration to include a second web server and a hardware load-balancer (preferably one that supports redudancy via multiple paths and devices, e.g. devices from Cisco, F5, or Foundry Networks). Often, however, running Apache on the ColdFusion server(s) provides adequate performance, and round-robin DNS records coupled with the ability to update DNS quickly in the event of a failure may be all you need for load-balancing and failover.