The document describes UBIC, a toolkit for writing daemons, init scripts, and services in Perl. It provides common classes that handle tasks like starting, stopping, and monitoring services that simplify writing init scripts. Services can be organized hierarchically and non-root users can run services. The toolkit also provides HTTP status endpoints and watchdog functionality to restart services that fail. UBIC sees widespread use at Yandex across many packages, clusters, and hosts.

1. UBIC
http://github.com/berekuk/ubic

2. UBIC
Toolkit for writing daemons, init scripts
and services in perl.
Batteries included.

3. case "$1" in
Usual way
start)
check_for_no_start
check_privsep_dir
echo -n "Starting OpenBSD Secure Shell server: sshd"
start-stop-daemon --start --quiet --pidfile /var/run/sshd.pid --exec /usr/sbin/sshd -- $SSHD_OPTS
echo "."
;;
stop)
echo -n "Stopping OpenBSD Secure Shell server: sshd"
start-stop-daemon --stop --quiet --oknodo --pidfile /var/run/sshd.pid
echo "."
;;
reload|force-reload)
check_for_no_start
check_config
echo -n "Reloading OpenBSD Secure Shell server's configuration"
start-stop-daemon --stop --signal 1 --quiet --oknodo --pidfile /var/run/sshd.pid --exec /usr/sbin/sshd
echo "."
;;
restart)
check_privsep_dir
check_config
echo -n "Restarting OpenBSD Secure Shell server: sshd"
start-stop-daemon --stop --quiet --oknodo --retry 30 --pidfile /var/run/sshd.pid
check_for_no_start
start-stop-daemon --start --quiet --pidfile /var/run/sshd.pid --exec /usr/sbin/sshd -- $SSHD_OPTS
echo "."
;;
*)
echo "Usage: /etc/init.d/ssh {start|stop|reload|force-reload|restart}"

4. Usual way
They are ugly.
They are verbose.
They are full of hacks.

5. Usual way
...and they don’t work consistently:
root@v5114:/etc/init.d# /etc/init.d/nscd start
Starting Name Service Cache Daemon: nscd (already running).
root@v5114:~# /etc/init.d/cron start
Starting periodic command scheduler: crond failed!
root@v5114:~# /etc/init.d/ssh start
root@v5114:~# SD Secure Shell server: sshdroot@v5114:~#
root@v5114:/etc/init.d# /etc/init.d/nscd status
Status of Name Service Cache Daemon service: not running.
root@v5114:/etc/init.d# /etc/init.d/cron status
Usage: /etc/init.d/cron {start|stop|restart|reload|force-reload}.
root@v5114:/etc/init.d# /etc/init.d/ssh status
Usage: /etc/init.d/ssh {start|stop|reload|force-reload|restart}

6. Better way
root # cat /etc/ubic/service/sleeping-daemon
use Ubic::Service::SimpleDaemon;
Ubic::Service::SimpleDaemon->new({
bin => '/bin/sleep 1000',
});

7. Better way
root # ubic start sleeping-daemon
Starting sleeping-daemon... started
root # ubic start sleeping-daemon
Starting sleeping-daemon... already running
root # ubic status
sleeping-daemon
running
ubic-ping
running

8. LSB 4.0 conformance
http://refspecs.freestandards.org/LSB_4.0.0/LSB-Core-
generic/LSB-Core-generic/iniscrptact.html
start
start the service
stop
stop the service
restart
stop and restart the service if the service is already running, otherwise start the service
try-restart
restart the service if the service is already running
reload
cause the configuration of the service to be reloaded without actually stopping and
restarting the service
force-reload
cause the configuration to be reloaded if the service supports this, otherwise restart the
service if it is running
status
print the current status of the service

9. Hierarchical services
mmcleric $ ubic status
Not a root, printing cached statuses
ubic-ping
running
yandex
yandex.swift-blogs-a
running
yandex.swift-blogs-b
running
yandex.swift-blogs-c
running
yandex.swift-blogs-d
running
yandex.swift-blogs-e
running
yandex-ppb-bulca-ds
yandex-ppb-bulca-ds.bulca_items
running
yandex-ppb-bulca-ds.bulca_items_retry
off
yandex-ppb-bulca-ds.index_blogs
running
yandex-ppb-bulca-ds.merge_swift
running
yandex-ppb-cache
yandex-ppb-cache.swift-blogs
yandex-ppb-cache.swift-blogs.lighttpd
running
yandex-ppb-cache.swift-blogs.fastcgi
running

10. Hierarchical services
root # ubic restart -f yandex-ppb-cache
yandex
Restarting yandex.swift-blogs-a... restarted
Restarting yandex.swift-blogs-b... restarted
Restarting yandex.swift-blogs-c... restarted
Restarting yandex.swift-blogs-d... restarted
Restarting yandex.swift-blogs-e... restarted

11. SysV init scripts
root # cat /etc/init.d/sleeping-daemon
#!/usr/bin/perl
use Ubic::Run; # that’s all!

12. Watchdog
root # killall sleep
root # ubic status
sleeping-daemon not running
ubic-ping running
root # ubic-watchdog
[ Fri Jun 11 03:06:32 2010 ]
sleeping-daemon is broken, restarting

13. HTTP ping
mmcleric $ wget -q -O - 'http://localhost:12345/status/service/sleeping-
daemon'
ok
mmcleric $ wget -O - 'http://localhost:12345/status/service/abc'
--03:31:21-- http://localhost:12345/status/service/abc
=> `-'
Resolving localhost... 127.0.0.1
Connecting to localhost|127.0.0.1|:12345... connected.
HTTP request sent, awaiting response... 404 Not found
03:31:21 ERROR 404: Not found.

14. Non-root users
root # cat /etc/ubic/service/sleeping-daemon
use Ubic::Service::SimpleDaemon;
Ubic::Service::SimpleDaemon->new({
bin => '/bin/sleep 1000',
user => 'nobody',
});

15. Common classes
mmcleric $ cat /etc/ubic/service/something
...
Ubic::Service::Common->new({
start => sub {
start_daemon({
bin => '/usr/bin/something’,
pidfile => '/var/tmp/something.pid',
stdout => "/var/log/something.log",
stderr => "/var/log/something.err.log",
ubic_log => "/var/log/something.ubic.log",
});
},
stop => sub {
stop_daemon('/var/log/something.pid');
},
status => sub {
check_daemon('/var/log/something.pid') ? 'running' : 'not running';
},
user => 'www-data',
});

16. Common classes
mmcleric $ cat /etc/ubic/service/something
...
Ubic::Service::PSGI->new({
server => 'Starman',
app => '/usr/share/something.psgi',
server_args => { workers => 3,
port => $port },
app_name => "something",
port => $port,
ubic_log => "$log_dir/ubic.log",
stdout => "$log_dir/stdout.log",
stderr => "$log_dir/stderr.log",
user => "www-data",
});

17. Common classes
Ubic::Service::Common
Ubic::Service::Lighttpd
Ubic::Service::Memcached
Ubic::Service::ProcManager
Ubic::Service::PSGI
Ubic::Service::SimpleDaemon
Ubic::Service::Skeleton
(not all of them are on cpan - yet)

18. Statistics
Usage in Yandex:
23 different packages
19 clusters
457 hosts

19. Credits
UBIC:
http://github.com/berekuk/ubic
http://search.cpan.org/dist/Ubic
Me:
Vyacheslav Matyukhin, Yandex
http://friendfeed.com/mmcleric
mailto:me@berekuk.ru
jabber:mmcleric@gmail.com