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Ubic::Manual::FAQ(3)  User Contributed Perl Documentation Ubic::Manual::FAQ(3)

NAME
       Ubic::Manual::FAQ - frequently asked questions about Ubic

VERSION
       version 1.58

QUESTIONS
   I changed my	service's user,	and now	it fails with "Permission denied"
       error. Please help!
       You have	to chown your service files manually. Try this:

	   find	/var/lib/ubic -name '*MY_SERVICE_NAME*'	| xargs	chown -R MY_NEW_USER

       In the future, this one-liner will be reimplemented as "ubic fix-
       permissions" command. Sorry for the inconvenience.

   Can I use ubic with perlbrew? How?
       Yes you can, but	you have to be careful.

       Perlbrew	depends	on environment variables, so you have to make sure
       that they are configured	correctly in all cases when you	call ubic.
       This especially includes	the crontab entry which	ubic installs for you.
       You'll probably have to edit it manually, like this:

	 * * * * * . /home/your_login/perl5/perlbrew/etc/bashrc	&& ubic-watchdog ubic.watchdog	  >>/dev/null 2>>/dev/null

   How is ubic compatible with SysV-style /etc/rcX.d/ symlinks?
       There are two ways of managing ubic service statuses across reboots.

       Don't use rc.d
	   Trust the ubic to manage service statuses for you. If you start a
	   service and then reboot, ubic.watchdog will bring it	back to	life
	   automatically.

	   This	is the recommended mode	of using ubic. (In other words,	this
	   is how author uses it.)

	   Downside: nobody will do "ubic stop"	on your	services before
	   reboot. shutdown(8) will send the SIGTERM, though, usually that's
	   all you need.

       Use rc.d
	   Turn	any ubic service into the init script using Ubic::Run.
	   Register it with rc.d using "chkconfig" or "update-rc.d" or however
	   your	OS wants you to	do it.

	   Downsides: 1) more manual work; 2) no persistent statuses: if you
	   stop	a service, forget to unregister	it from	rc.d, and then reboot,
	   it will start again.

	   Upside: runlevels.

   Why do I get	confusing error	messages when I	try to add the service with a
       dot in its name?
       Dot is a	reserved symbol, it separates service name parts in service
       tree (like "/" separates	directories in unix filesystems). So, if you
       really want the service "foo.bar", put its description in
       "/etc/ubic/service/foo/bar".

       Dot in config file names	is used	to distinguish different configuration
       styles. Extension-less configs are pure-perl, *.ini is ini configs,
       etc.

   Why ubic creates a new daemon every minute in an endless loop if my binary
       daemonizes itself?
       Ubic can't distinguish self-daemonizing binary from program which
       instantly exits,	so "ubic.watchdog" thinks that the service has failed
       and tries to respawn it every minute.

       You can either fix the daemon (hint: many daemons have some kind	of
       "--foreground" option), or implement your own service class.

       See Ubic::Service, Ubic::Service::Skeleton, Ubic::Service::Common and
       "Common service classes"	in Ubic::Manual::Overview for more details on
       writing custom service classes.

   Why did ubic	edit my	crontab?
       Ubic uses cron as the way to bootstrap all its services.	This crontab
       entry will bring	the "ubic.watchdog" up if it ever goes down, and it
       will then start all other services as necessary.

       Even though watchdog itself is very robust, this	mechanism is also
       useful on host reboots.

       If you really don't like	it, you	can pass "--no-crontab"	option to
       "ubic-admin setup" command while	configuring ubic instance (or just
       answer "no" to the appropriate question).

   What	is this	ubic-guardian process I	see in my "ps aux" output?
       This process guards any daemon started with "Ubic::Daemon" module.

       Optionally, ubic-guardian can write some	information to its log,	for
       example,	the exit code or signal	in case	of service failure. Despite
       its name, ubic-guardian *does not* restart the service on failures.
       It's the	job for	the completely different program, ubic-watchdog.

       It also holds the lock on the pidfile for a whole lifetime, which
       theoretically makes daemons more	secure,	but it's more of a historical
       nuance than the necessity.

       It's probable that ubic-guardian	will become optional in	the future
       (i.e. it	will only be created if	service	asks for ubic_log).  Anyway,
       don't worry about it, it's completely harmless.

   What	does ubic.update service do?
       "ubic.update" service (and ubic-update script) updates portmap -	local
       "{ port => service-name }" mapping.  It makes possible to check a
       service status via "ubic.ping" using service port instead of its	name:

	   $ wget -q -O	- 'http://localhost:12345/status/port/12345'
	   ok

       Resolving of service by port can't be done on-the-fly by	"ubic.ping",
       because all service definitions are cached internally by	Ubic.pm
       (Ubic::Multiservice, actually, but you don't have to know the
       difference), since constant reloading of	service	definition can cause
       memory leaks.  So "ubic.ping" just loads	portmap	generated by
       "ubic.update" instead, resolves service name by port, and loads cached
       service status from another local file.

       In other	words, if you don't use	"ubic.ping", you can stop both
       "ubic.update" and "ubic.ping" services.

   Why is it called "ubic", anyway?
       It's called after "Ubik"	- science fiction novel	by Philip K. Dick. I
       spelled it incorrectly in early releases, because "c" and "k" are
       indistinguishable in Russian language, and now it's too late to fix
       this.

       Why is it called	after "Ubik"? Well, these two quotes can hint to some
       suggestions:

	 "This substance, whose	name is	derived	from the word "ubiquity", has the property of preserving people	who are	in half-life."
	 "Ubik is a metaphor for God. Ubik is all-powerful and all-knowing, and	Ubik is	everywhere."

       Alternatively, one possible backronym is	"Ubic Because I	Can" :)
       (Thanks to Christopher Paulicka for suggesting it!)

AUTHOR
       Vyacheslav Matyukhin <mmcleric@yandex-team.ru>

COPYRIGHT AND LICENSE
       This software is	copyright (c) 2015 by Yandex LLC.

       This is free software; you can redistribute it and/or modify it under
       the same	terms as the Perl 5 programming	language system	itself.

perl v5.32.1			  2015-01-27		  Ubic::Manual::FAQ(3)

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