Re: spontaneous redeployment of a webapp

On 10/12/2025 18:52, Linus Kamb wrote:
> All,
> 
> Context:
> We have several public facing tomcats (all behind a firewall, no fronting
> Apache.)  They are mostly 10.1.44, but there is one 8.5.100.  There is a
> mix of webapps on all of them, but they all have one particular webapp in
> common.  That webapp often uses a fair amount of memory.  (Not sure if that
> is relevant here.)
> 
> Situation:
> The night before last *all* of the instances of that particular common
> webapp were undeployed and redeployed in the middle of the night. (3 at
> ~1am, 1 at ~2am, and 2 at ~2:30.)  There was no apparent nefarious network
> traffic, and in several cases, no network access to the tomcats at all for
> hours in either direction.  And the timestamps of the war files and web.xml
> files had not (or do not appear to have) changed.
> 
> One possibly significant detail is that around that time, the disk from
> which all the tomcats run was on the edge (and occasionally over that edge)
> of running out of space.  For instance, in some cases where it didn't
> already exist, tomcat reported it was unable to create the
> catalina.2025-12-09.txt log file as there was no space on the device, which
> it was presumably trying to create to log the undeployment and redeployment
> of the webapp.  (It was logged there in other tomcats where the file
> already existed.)
> 
> There were no OutOfMemoryErrors thrown by any of the tomcats, and none of
> the tomcats themselves were shut down and restarted.  Just all the
> instances of that one webapp in all the tomcats reloaded.
> 
> Any ideas what might have happened?  Have you ever seen anything like
> this?   Can Tomcat spontaneously redeploy specific webapps unprompted?

Is there some form of shared disk arrangement between multiple machines 
here? Is the web application on the shared disk?

If the shared disk goes off-line for any reason and auto-deployment is 
enabled, Tomcat will undeploy the web application and redeploy it when 
the shared disk returns.

Mark