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Ubic-1.29
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NAME

Ubic::Manual::Intro - General ubic concepts and architecture

VERSION

version 1.29

DESCRIPTION

Ubic is a perl-based service manager.

Ubic can run any program as a service and provides frontend script ubic to manage services.

Ubic includes centralized watchdog process which checks every service periodically and brings them back online if necessary.

GLOSSARY

Service

Ubic service is an object describing how your service works.

Service object must conform to the API of the Ubic::Service class, so it must implement start, stop and status methods.

It can also provide other methods: which user should be used to run the service, how often the service should be checked by the watchdog, etc.

Service class

Most services don't implement start/stop methods themselves. Instead, they are declared as instances of some existing service class, for example, Ubic::Service::SimpleDaemon.

Service dir

Service declarations are stored in ubic service dir.

Service delaration is a single file with perl code which returns service object when executed with do.

If you're using host-level installation, service dir is /etc/ubic/service. If you're using installation to home dir, service dir is ~/ubic/service.

Multiservice and service tree

Service dir can contain another type of object: multiservices.

Multiservice is an object implementing Ubic::Multiservice API.

Multiservices allow to generate a list of services dynamically and fill it by other means than by writing perl code for each service.

All services collected by evaluation of service delaration and traversing multiservices, make up the service tree.

Status

Every service implements status() method. You can see it by invoking ubic status command from terminal.

Watchdog

Default installation provides some services out of the box. The most important of them is ubic.watchdog.

Watchdog service checks every service status periodically and restarts them if they broke.

INSTALLATION

Installing Ubic is easy.

First, install the module using your favorite CPAN client, for example, cpanm Ubic.

Second, invoke ubic-admin script to perform initial configuration: ubic-admin setup.

If you don't like that setup process asks too many questions, you can invoke it as ubic-admin setup --batch-mode --quiet.

Alternatively, if you're using Debian or Ubuntu, you can install ubic .deb package from official launchpad PPA repository: https://launchpad.net/~berekuk/+archive/ubic.

WRITE YOUR FIRST SERVICE

Put this code in your service dir, i.e. in file /etc/ubic/service/example (or if you're using home-dir installation, in ~/ubic/service/example):

use Ubic::Service::SimpleDaemon;
Ubic::Service::SimpleDaemon->new(
    bin => 'sleep 1000',
);

Start it:

$ ubic start example
Starting example... started (pid 41209)

Check its status:

$ ubic status
example running (pid 41209)
ubic
    ubic.ping   off
    ubic.update off
    ubic.watchdog   running (pid 93226)

Or:

$ ubic status example
example running (pid 41209)

Now let's see how watchdog works by killing the process (don't forget to change pid with the pid you got in status command above):

$ kill 41209

$ ubic status example
example not running

$ ubic-watchdog
[Thu May 26 20:20:54 2011]  example is broken, restarting

You don't have to run ubic-watchdog manually; it will do its work in background in a minute.

SEE ALSO

Ubic::Service::SimpleDaemon allows you to tune other service aspects other than bin. Check it out.

Series of blog posts written as tutorials

AUTHOR

Vyacheslav Matyukhin <mmcleric@yandex-team.ru>

COPYRIGHT AND LICENSE

This software is copyright (c) 2011 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.