mod_jk load balancing and cluster node health

["Nathan E. Pilling" <np...@corda.com>]

Is it possible to configure mod_jk to check node status by requesting a specific web application path to see if a cluster node is healthy (and should be included or excluded from the cluster)?

I have a web application that runs across multiple tomcat instances and any request be processed by any tomcat node. If an instance of the web app on one of the tomcat servers is not configured properly, I want the connector to exclude it from the cluster.

I have written a servlet that returns a status of 503 if something is wrong or 200 if everything is okay.

Thanks,
Nathan Pilling

Re: mod_jk load balancing and cluster node health

[Rainer Jung <ra...@kippdata.de>]

Nathan E. Pilling wrote:
> Is it possible to configure mod_jk to check node status by requesting
> a specific web application path to see if a cluster node is healthy
> (and should be included or excluded from the cluster)?
> 
> I have a web application that runs across multiple tomcat instances
> and any request be processed by any tomcat node. If an instance of
> the web app on one of the tomcat servers is not configured properly,
> I want the connector to exclude it from the cluster.
> 
> I have written a servlet that returns a status of 503 if something is
> wrong or 200 if everything is okay.

There's not the full story build in yet, but you can combine the various 
pieces to get the same result:

Write an external script, that refularly calls your servlet and add 
";jsessionid=.MYNODENAME" to the end of the URL (but before the query 
string). The load balancer will then send the request to it's member 
named "MYNODENAME" (stickyness).

Now you set fail_on_status to 503 for all LB members. Then the load 
balancer should put the node into ERROR, whenever it sees a 503 coming 
back for any request.

See http://tomcat.apache.org/connectors-doc/reference/workers.html for 
fail_on_status.

Does that sound plausible?

> Thanks, Nathan Pilling

Regards,

Rainer

---------------------------------------------------------------------
To start a new topic, e-mail: users@tomcat.apache.org
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org