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tomcat7 init script is asynchronous

2015-02-26 by t.glaser@tarent.de (EvolvisForge blog)
Tags: work debian

TIL: the init script of tomcat7 in Debian is asynchronous.

For some piece of software, our rollout (install and upgrade) process works like this:

  • service tomcat7 stop
  • rm -rf /var/lib/tomcat7/webapps/appname{,.war}
  • cp newfile.war /var/lib/tomcat7/webapps/appname.war
  • service tomcat7 start # ← here
  • service tomcat7 stop
  • edit some config files under /var/lib/tomcat7/webapps/appname/WEB-INF/
  • service tomcat7 start

The first tomcat7 start “here” is just to unzip the *.war files. For some reason, people like to let tomcat7 do that.

This failed today; there were two webapps. Manually unzipping it also did not work for some reason.

Re-doing it, inserting a sleep 30 after the “here”, made it work.

In a perfect world, initscripts only return when the service is running, so that the next one started in a nice sequential (not parallel!) init or manual start sequence can do what it needs to, assuming the previous command has fully finished.

In this perfect world, those who do wish for faster startup times use a different init system, one that starts things in parallel, for example. Even there, dependencies will wish for the depended-on service to be fully running when they are started; even more so, since the delays between starting things seem to be less for that other init system.

So, this is not about the init system, but about the init script; a change that would be a win-win for users of both init schemes.

Update: Someone already contacted me with feedback: they suggested to wait until the “shutdown port” is listened on by tomcat7. We’ll look at this later. In the meantime, we’re trying to also get rid of the “config (and logs) in webapps/” part…


PS: If someone is interested in an init script (Debian/LSB sysvinit, I made the effort to finally learn that… some months before the other system came) that starts Wildfly (formerly known as JBoss AS) synchronously, waiting until all *.?ar files are fully “deployed” before returning (though with a timeout in case it won’t ever finish), just ask (maybe it will become a dialogue, in which we can improve it together). (We have two versions of it, the more actively maintained one is in a secret internal project though, so I’d have to merge it and ready it for publication though, plus the older one is AGPLv3, the newer one was relicenced to a BSDish licence.)

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