# PODNAME: App::CharmKit::Manual::WritingHooks
# ABSTRACT: How to write hooks using CharmKit

__END__

=pod

=encoding UTF-8

=head1 NAME

App::CharmKit::Manual::WritingHooks - How to write hooks using CharmKit

=head1 VERSION

version 0.011

=head1 Creating a hook

  $ charmkit generate config-changed

This places a templated hook in B<src/hooks/> where all hook development resides.

=head1 Writing a hook

We'll start with an example of a F<config-changed> hook and break down the
code piece by piece

  #!/usr/bin/env perl
  use charm;

C<use charm> is the entrypoint to exposing charm routines useful for deploying
the service. This provides facilities such as installing packages, printing logs,
getting relation information, and configuring service level options.

  log "Start of charm authoring for config-changed";

The C<log> facility uses C<juju-log> as the utility for logging what's happening
in your charm.

  my $port = config_get('port');

C<config_get> routine will pull config options defined in F<config.yaml>.

  # close existing bitlbee port

  log "Opening port for bitlbee";

  ( my $output = qq{BITLBEE_PORT=$port
  BITLBEE_OPTS="-F"
  BITLBEE_DISABLED=0
  BITLBEE_UPGRADE_DONT_RESTART=0
  } );

  path('/etc/default/bitlbee')->spew_utf8($output);

C<path> is exposed from L<Path::Tiny> so anything that applies to that module works
the same here.

  service_control('bitlbee', 'restart');

C<service_control> is another helper for start/stopping services on the system
where the charm is placed.

  open_port($port);

C<open_port> exposes a port accessible publicly, and its opposite C<close_port> will
remove that accessibility.

=head1 Further reading

There are several helpers exposed automatically in order to simply the writing of
hooks. To see what helpers are available look at the module documentation:

=over 4

=item *

L<App::CharmKit::Sys>

System utilities

=item *

L<App::CharmKit::Logging>

Logging utilities

=item *

L<App::CharmKit::Helper>

Charm specific utilities

=back

=head1 AUTHOR

Adam Stokes <adamjs@cpan.org>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2014 by Adam Stokes.

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

=head1 DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT
WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER
PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,
EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE
SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME
THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
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SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.

=cut
