Ubic is a flexible Perl-based polymorphic service manager. It allows services to be configured and managed through Perl code and provides APIs for starting, stopping and checking the status of services. Services can inherit behaviors from other service classes and be organized hierarchically into multiservices. The service state is persisted even after reboots. Various service loaders allow services to be configured through different file formats like ini files to support non-Perl users. The project aims to improve cross-platform support and provide additional features through plugins.

1. Friends, this is clean-up time and we're
discounting all our silent, electric Ubiks
by this much money. Yes' we're throwing
away the bluebook. And remember: every Ubik
on our lot has been used only as directed.
Phillip K. Dick. “Ubik”.
Ubic
Polymorphic service manager
github.com/berekuk/ubic

2. 1-minute intro

3. Install
Debian/Ubuntu:
apt-add-repository ppa:berekuk/ubic && apt-get install ubic
FreeBSD:
cd /usr/ports/sysutils/p5-Ubic && make install
Everywhere else:
cpanm Ubic && ubic-admin setup

4. Write service config
# cat >/etc/ubic/service/foo
use Ubic::Service::SimpleDaemon;
Ubic::Service::SimpleDaemon->new(
bin => ‘sleep 1000’,
stdout => ‘/var/log/foo.log’,
);

5. Run it
# ubic start foo
Starting foo... started (pid 28152)

6. Flexible perl-based
service manager

7. Flexible perl-based
polymorphic
service manager

8. APIs everywhere

9. I’ll talk about APIs
instead of features today
• Ubic.pm glue code
• services
• multiservices
• service loaders

10. Ubic.pm API

11. Ubic.pm API
Ubic->start(‘foo’);
Ubic->stop(‘foo’);
# and many other methods

12. Service state is different from
service status
# ubic status foo
foo running (pid 29551)
# kill 29551
# ubic status foo
foo not running
# ubic stop foo
Stopping foo... not running
# ubic status
foo off

13. Watchdog adjusts service status
in accordance with service state.
# ubic status foo
foo running (pid 29551)
# kill 29551
# ubic status foo
foo not running
# ubic-watchdog foo
[Fri Dec 9 03:45:37 2011] foo status is 'not running',
restarting

14. Ubic is not a supervisor
There is no global supervisor process.
Ubic is more similar to init scripts than
to upstart or launchd in this aspect.

15. Service state is persistent
• state is stored on disk and kept even after
reboot
• you don’t have to stop services on host
shutdown and start them on reboot
(I know some people want a proper
shutdown; I’ll get to that later)

16. Ubic.pm API
consumers
• /usr/bin/ubic — command-line frontend
• ubic.watchdog service — monitors everything
• ubic.ping — reports service status via http

17. Ideas for more features
• ubic-web — html app frontend
• ‘ubic shutdown’ command which stops
everything but don’t change state
• parameterized commands

18. Services API

19. Service is an object
Services conform to simple API:
use parent qw(Ubic::Service);
sub start { ... }
sub stop { ... }
sub status { ... }

20. Start code
can get complicated
use parent qw(Ubic::Service);
sub start {
# check if daemon is running
# start daemon
# sleep for some time
# check status
# sleep more
# check status
# ... etc
}

21. So Ubic::Service::Skeleton
provides shortcuts
use parent qw(Ubic::Service::Skeleton);
sub start_impl { ... }
sub start_impl { ... }
sub status_impl { ... }
sub timeout_options
{ start => { step => 0.1, trials => 3 } }
}

22. Services inherit from
other services
Ubic::Service
Ubic::Multiservice Ubic::Service::Skeleton
Ubic::Service::SimpleDaemon Ubic::Service::InitScriptWrapper
Ubic::Service::ZooKeeper Ubic::Service::MongoDB
Ubic::Service::Plack Ubic::Service::Memcached
Ubic::Service::Starman

23. Custom status() methods
Example from Ubic::Service::MongoDB
sub status_impl {
my $self = shift;
my $running = check_daemon($self->pidfile);
return result('not running') unless $running;
my $status = MongoDB::Connection->new(...)->admin->run_command({ serverStatus => 1 });
if (!$status->{ok} || $status->{ok} != 1) {
return result('broken');
} else {
return result('running');
}
}

24. SimpleDaemon is the
most popular service class
Ubic::Service::SimpleDaemon->new(
bin => ‘plackup /usr/share/foo/app.psgi’,
stdout => ‘/var/log/foo.log’,
stderr => ‘/var/log/foo.err.log’,
ubic_log => ‘/var/log/foo.ubic.log’,
user => ‘daemon’,
group => ‘daemon’,
cwd => ‘/’,
env => { PERL5LIB => ‘/usr/share/foo/lib’ },
};

25. Ideas for
new service modules
• restart (report ‘broken’ status) on
memory leaks
• or on code changes
• or once per N seconds
• or if service doesn’t answer http ping
(parameterize with url, port and
timeout)

26. More ideas for
new service modules
• better mechanism for adding features
(decorators/roles/middlewares)
• simple daemonizer which uses
Proc::Daemon instead of Ubic::Daemon
• wrappers for other service managers
(turn daemontools service to ubic
service)

27. Multiservices API

28. All services belong to
the global service tree
# ubic status
foo running (pid 1234)
bar running (pid 1235)
ubic
ubic.ping running (pid 2182)
ubic.update running (pid 2181)
ubic.watchdog running (pid 1996)

29. Files in service dir describe
services with perl code
# cat /etc/ubic/service/foo
use Ubic::Service::SimpleDaemon;
Ubic::Service::SimpleDaemon->new(
bin => ‘sleep 1000’,
stdout => ‘/var/log/foo.log’,
);

30. Subdirectories
become multiservices
# ls ~/ubic/service/ubic/
ping update watchdog
# ubic status ubic
ubic
ubic.ping running (pid 2182)
ubic.update running (pid 2181)
ubic.watchdog running (pid 1996)

31. Or you can implement
multiservice in perl
# cat /etc/ubic/service/psgi
use parent qw(Ubic::Multiservice);
use Ubic::Service::Plack;
sub simple_service {
my ($self, $name) = @_;
return Ubic::Service::Plack->new(...);
}
sub service_names {
my @configs = glob “/psgi_apps/*.psgi”;
s{^/psgi_apps(.*).psgi$}{$1} for @configs;
return @configs;
}

32. Another use case:
create N services
use Ubic::Multiservice::Simple;
use Ubic::Service::SimpleDaemon;
return Ubic::Multiservice::Simple->new({
map {
"worker$_" =>
Ubic::Service::SimpleDaemon->new({
bin => "/usr/bin/worker.pl",
})
} (1..10)
});

33. Ideas for more
multiservices
• bind the whole /etc/init.d/ or /service/
to ubic
• “stash” multiservice — create services
from command-line without creating
any configs

34. Service loaders

35. Configs with .ini
extension are different
# cat /etc/ubic/service/foo.ini
module = Ubic::Service::SimpleDaemon
[options]
bin = sleep 1000
stdout = /var/log/foo.log

36. Configs with any
extension are different
• ini configs are loaded with
Ubic::ServiceLoader::Ext::ini
• experimental yaml service loader is in
separate repo (not sure if extra
dependency is worth it)

37. Now we can reach to
non-perl users
• Node.JS guys at Yandex use Ubic
• Java guys at Yandex use Ubic
• admins who don’t know Perl use Ubic
• all of them do it because they like it, not
because I forced them :)
• tell your non-perl friends about Ubic
today!

38. Ideas for more
service loaders
• .bin — turn symlink to binary into
service
• new [addons] section to ini config,
which would wrap service object in
listed decorators
• .xml, .json (I know we don’t need so
many of different formats, but Node.JS
people like to reinvent the wheel)

39. More ideas

40. There are no
cross-platform service managers
• Let’s port Ubic to Windows!
• several guys tried to help but disappeared
• github.com/berekuk/Ubic/wiki/Windows
is the current plan

41. Plugins
• add a new command to /usr/bin/ubic
• or add memory leaks monitoring to all
services at once
• API: apply the given middleware to all
services

42. The End

43. Questions? Patches?
github.com/berekuk/Ubic
#ubic at irc.perl.org
“Like” Ubic on metacpan: metacpan.org/release/Ubic

44. This is the slide #42