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August 2014

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Subject:
From:
Vladimir Mosgalin <[log in to unmask]>
Reply To:
Vladimir Mosgalin <[log in to unmask]>
Date:
Tue, 26 Aug 2014 03:36:54 +0400
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Hi Ken Teh!

 On 2014.08.25 at 12:58:21 -0500, Ken Teh wrote next:

> I read the following article on systemd
> 
> http://ifwnewsletters.newsletters.infoworld.com/t/9625863/474699771/826094/14/
> 
> The comments suggested one could still revert to sysvinit.  Is this just wishful thinking on my part?

Yes. As an exercise, why don't you revert EL6's upstart to sysvinit?
Note that enabling/disabling some services on EL6 *requires* you to use
upstart-specific initctl, you simply won't notice these services if you
will only look at chkconfig.

systemd offers many benefits for system administrators, like:
- simple and predictable service files
- ability to wrap a random application into service with just a few lines of config
- no more extra-complicated init scripts using various hacks and magic
for non-C applications (if you ever tried to wrap some random python or
java application into service, you'll know what I'm talking about right
away)
- automatic restart of services
- thanks to these features (service created with few lines of code,
automatic restart, some others) - no more need for runit, daemontools or
supervisord , you can have all the benefits of these systems while having
only one flat init system (systemd) for both system and your services
- reliable pid tracking, which even follows the forks - that's something
not current init system or others like runit are able to do. No more
hassle with complex pgrep's for applications that didn't leave pidfile
behind (again, applications that rename or fork themselves and non-C
applications can be extremely annoying here). But systemd has reliable
way of knowing all the pids that each service has created without any
hacks at all - thanks to cgroups support.
- ... many more, like various niceties for supporting lightweight
containers with blazing fast startup, where systemd cares about
organizing namespaces and initializing network by itself (not sure these
features are in EL7's systemd, though)

really, for everyone who spent many hours wrapping developers'
applications into services or had to bother with various hacks and
scripts "to let this stupid application daemonize more easily" like
forever, runit, supervisord or misses various features of solaris smf in
linux, systemd is a real bliss.

-- 

Vladimir

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