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From André Warnier ...@ice-sa.com>
Subject Re: Monitoring Tomcat availability in a load balanced capacity
Date Thu, 13 Nov 2008 22:59:11 GMT
Not to interfere with Dave, but just as another halfway idea :
You could define 2 other workers in the Jk config, which are not 
load-balanced, each going to one Tomcat.
You would still not be testing the exact same path as the clients, but 
would be checking Apache, mod_jk itself and the Tomcats.

Adam Gordon wrote:
> We've discovered a problem with simply adding another (HTTP) Connector 
> in that by allowing a different form of connection to our web app and 
> using this connector for our monitoring, we aren't testing the path that 
> a user would take, which is through the load balancer and mod JK.  One 
> of the issues we had was that we had an errant script that was rsync-ing 
> from one Tomcat server to the other (when we had one active and one as a 
> backup) to ensure that the second machine was always up-to-date with the 
> latest version of the web app.  When we went from active/passive to 
> active/active w/ a load-balancer, we forgot to remove this script so the 
> server.xml file, where the JVM Route is defined, was getting clobbered 
> with the source Tomcat server's server.xml file and causing major 
> accessibility issues.  Having another connector and using that for our 
> monitoring would actually have told us that the server was fine when in 
> fact no one could get to it because Apache became confused when it now 
> has two load balanced servers but they both have the same JVM Route.
> 
> The 'wget' command allows the user to play with Cookies so our next step 
> is to see if we can specify a fake JSESSIONID in cookie form to see if 
> we can dictate to which server Apache will send us.  As previously 
> mentioned, we cannot simply put this on the URL as a parameter because 
> we are using sticky sessions.
> 
> --adam
> 
> David Rees wrote:
>> On Wed, Nov 12, 2008 at 1:15 PM, Adam Gordon 
>> <adam.gordon@readytalk.com> wrote:
>>  
>>> See my reply to Hassan.  I think setting up a proxy would be 
>>> overkill, and
>>> besides, when running Tomcat in a load-balanced capacity w/ sticky 
>>> sessions
>>> using mod JK, while you can connect directly to the port on which 
>>> Tomcat is
>>> listening for mod JK requests, unless you speak mod JK, it doesn't do
>>> anything.
>>>     
>>
>> Did you not see my earlier post? It sounds like you should be able to
>> do what you want without any configuration changes at all.
>>
>> -Dave
>>
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>>  
>>   
> 
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