Ubic YAPC 2012

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

1-minute intro

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

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

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

Flexible perl-based service manager

Flexible perl-based polymorphic service manager

APIs everywhere

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

Ubic.pm API

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

Service state is different fromservice status# ubic status foofoo running (pid 29551)# kill 29551# ubic status foofoo not running# ubic stop fooStopping foo... not running# ubic statusfoo off

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

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

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)

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

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

Services API

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

Start codecan 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 }

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 } } }

Services inherit from other services Ubic::ServiceUbic::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

Custom status() methods Example from Ubic::Service::MongoDBsub 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); }}

SimpleDaemon is themost 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’ }, };

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)

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)

Multiservices API

All services belong tothe global service tree# ubic statusfoo running (pid 1234)bar running (pid 1235)ubic ubic.ping running (pid 2182) ubic.update running (pid 2181) ubic.watchdog running (pid 1996)

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’, );

Subdirectoriesbecome 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)

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; }

Another use case:create N servicesuse 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)});

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

Service loaders

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

Conﬁgs with anyextension 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)

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!

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)

More ideas

There are nocross-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

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

The End

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

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Ubic YAPC 2012

by Vyacheslav Matyukhin

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