File Coverage

blib/lib/Mojolicious/Plugin/Systemd.pm

Criterion	Covered	Total	%
statement	60	60	100.0
branch	28	32	87.5
condition	13	17	76.4
subroutine	13	13	100.0
pod	1	1	100.0
total	115	123	93.5

package Mojolicious::Plugin::Systemd;
use Mojo::Base 'Mojolicious::Plugin';

use Mojo::File 'path';
use Mojo::Util qw(trim unquote);

use constant DEBUG => $ENV{MOJO_SYSTEMD_DEBUG} || 0;

our $VERSION = '0.01';

has config_map => sub {
  return {
    hypnotoad => {
      accepts            => sub { (MOJO_SERVER_ACCEPTS            => 0) },
      backlog            => sub { (MOJO_SERVER_BACKLOG            => 0) },
      clients            => sub { (MOJO_SERVER_CLIENTS            => 0) },
      graceful_timeout   => sub { (MOJO_SERVER_GRACEFUL_TIMEOUT   => 0) },
      heartbeat_interval => sub { (MOJO_SERVER_HEARTBEAT_INTERVAL => 0) },
      heartbeat_timeout  => sub { (MOJO_SERVER_HEARTBEAT_TIMEOUT  => 0) },
      inactivity_timeout => sub { (MOJO_SERVER_INACTIVITY_TIMEOUT => 0) },
      listen          => sub { (MOJO_LISTEN                 => [qr{\s+}]) },
      pid_file        => sub { (MOJO_SERVER_PID_FILE        => '') },
      proxy           => sub { (MOJO_SERVER_PROXY           => 0) },
      requests        => sub { (MOJO_SERVER_REQUESTS        => 0) },
      spare           => sub { (MOJO_SERVER_SPARE           => 0) },
      upgrade_timeout => sub { (MOJO_SERVER_UPGRADE_TIMEOUT => 0) },
      workers         => sub { (MOJO_SERVER_WORKERS         => 0) },
    },
  };
};

sub register {
  my ($self, $app, $config) = @_;
  $self->_merge_config_map($config->{config_map}, $self->config_map)
    if $config->{config_map};

  my $file = $config->{service_file} || $ENV{SYSTEMD_SERVICE_FILE};
  $self->_parse_unit_file($file) if $file or $ENV{XDG_SESSION_ID};

  $self->_config_from_env($app->config, $self->config_map);
}

sub _config_from_env {
  my ($self, $config, $config_map) = @_;

  for my $k (sort keys %$config_map) {
    if (ref $config_map->{$k} eq 'HASH') {
      $self->_config_from_env($config->{$k} ||= {}, $config_map->{$k});
    }
    elsif (ref $config_map->{$k} eq 'CODE') {
      my ($ek, $template) = $config_map->{$k}->();
      warn sprintf "[Systemd] config %s=%s\n", $ek, $ENV{$ek} // '' if DEBUG;
      $config->{$k} = $self->_config_val($ENV{$ek}, $template)
        if defined $ENV{$ek};
    }
  }
}

sub _config_val {
  my ($self, $val, $template) = @_;
  return ref $template eq 'ARRAY' ? [split $template->[0], $val] : $val;
}

sub _merge_config_map {
  my ($self, $source, $target) = @_;

  for my $k (sort keys %$source) {
    if (!defined $source->{$k}) {
      delete $target->{$k};
    }
    elsif (ref $source->{$k} eq 'HASH') {
      $self->_merge_config_map($source->{$k}, $target->{$k} ||= {});
    }
    elsif (ref $source->{$k} eq 'CODE') {
      $target->{$k} = $source->{$k};
    }
  }
}

sub _parse_environment_file {
  my ($self, $file) = @_;
  warn sprintf "[Systemd] EnvironmentFile=%s\n", $file if DEBUG;

  my $flag = $file =~ s!^(-)!! ? $1 : '';
  return if $flag eq '-' and !-r $file;

  my $FH = path($file)->open;
  while (<$FH>) {
    $self->_set_environment($1, $2) if /^(\w+)=(.*)/;
  }
}

sub _parse_unit_file {
  my ($self, $file) = @_;

  warn sprintf "[Systemd] SYSTEMD_UNIT_FILE=%s\n", $file if DEBUG;
  my $UNIT = path($file || 'SYSTEMD_UNIT_FILE_MISSING')->open;
  while (<$UNIT>) {
    $self->_set_multiple_environment($1)       if /^\s*\bEnvironment=(.+)/;
    $self->_parse_environment_file(unquote $1) if /^\s*\bEnvironmentFile=(.+)/;
    $self->_unset_multiple_environment($1)     if /^\s*\bUnsetEnvironment=(.+)/;
  }
}

sub _set_environment {
  my ($self, $key, $val) = @_;
  warn sprintf "[Systemd] set %s=%s\n", $key, unquote($val // 'undef') if DEBUG;
  $ENV{$key} = unquote $val;
}

sub _set_multiple_environment {
  my ($self, $str) = @_;
  $str =~ s!\#.*!!;

  # "FOO=word1 word2" BAR=word3 "BAZ=$word 5 6" FOO="w=1"
  while ($str =~ m!("[^"]*"|\w+=\S+)!g) {
    my $expr = unquote $1;
    $self->_set_environment($1, $2) if $expr =~ /^(\w+)=(.*)/;
  }
}

sub _unset_multiple_environment {
  my ($self, $str) = @_;

  for my $k (map { trim unquote $_ } grep {length} split /\s+/, $str) {
    warn sprintf "[Systemd] unset %s\n", $k if DEBUG;
    delete $ENV{$k};
  }
}

1;

=encoding utf8

=head1 NAME

Mojolicious::Plugin::Systemd - Configure your app from within systemd service file

=head1 SYNOPSIS

=head2 Example application

  package MyApp;
  use Mojo::Base "Mojolicious";
  sub startup {
    my $app = shift;
    $app->plugin("Systemd");
  }

=head2 Example systemd unit file

    [Unit]
    Description=MyApp service
    After=network.target

    [Service]
    Environment=SYSTEMD_SERVICE_FILE=/etc/systemd/system/my_app.service
    Environment=MOJO_SERVER_PID_FILE=/var/run/my_app.pid
    Environment=MYAPP_HOME=/var/my_app
    EnvironmentFile=-/etc/default/my_app

    User=www
    Type=forking
    PIDFile=/var/run/my_app.pid
    ExecStart=/path/to/hypnotoad /home/myapp/script/my_app
    ExecReload=/path/to/hypnotoad /home/myapp/script/my_app
    KillMode=process
    SyslogIdentifier=my_app

    [Install]
    WantedBy=multi-user.target

=head1 DESCRIPTION

L is a L plugin that allows your
application to read configuration from a Systemd service (unit) file.

It works by parsing the C, C and
C statements in the service file and inject those environment
variables into your application. This is especially useful if your application
is run by L, since you cannot "inject" environment
variables into a running application, meaning C below won't change
anything in your already started application:

  $ SOME_VAR=42 /path/to/hypnotoad /home/sri/myapp/script/my_app

See L
for more information about C, C and C.

=head1 ATTRIBUTES

=head2 config_map

  $hash_ref = $self->config_map;

Returns a structure for how L can be set from environment
variables. By default the environment variables below are supported:

  $app->config->{hypnotoad}{accepts}            = $ENV{MOJO_SERVER_ACCEPTS}
  $app->config->{hypnotoad}{backlog}            = $ENV{MOJO_SERVER_BACKLOG}
  $app->config->{hypnotoad}{clients}            = $ENV{MOJO_SERVER_CLIENTS}
  $app->config->{hypnotoad}{graceful_timeout}   = $ENV{MOJO_SERVER_GRACEFUL_TIMEOUT}
  $app->config->{hypnotoad}{heartbeat_interval} = $ENV{MOJO_SERVER_HEARTBEAT_INTERVAL}
  $app->config->{hypnotoad}{heartbeat_timeout}  = $ENV{MOJO_SERVER_HEARTBEAT_TIMEOUT}
  $app->config->{hypnotoad}{inactivity_timeout} = $ENV{MOJO_SERVER_INACTIVITY_TIMEOUT}
  $app->config->{hypnotoad}{listen}             = [split /\s+/, $ENV{MOJO_LISTEN}];
  $app->config->{hypnotoad}{pid_file}           = $ENV{MOJO_SERVER_PID_FILE}
  $app->config->{hypnotoad}{proxy}              = $ENV{MOJO_SERVER_PROXY}
  $app->config->{hypnotoad}{requests}           = $ENV{MOJO_SERVER_REQUESTS}
  $app->config->{hypnotoad}{spare}              = $ENV{MOJO_SERVER_SPARE}
  $app->config->{hypnotoad}{upgrade_timeout}    = $ENV{MOJO_SERVER_UPGRADE_TIMEOUT}
  $app->config->{hypnotoad}{workers}            = $ENV{MOJO_SERVER_WORKERS}

=head1 METHODS

=head2 register

  $app->plugin("Systemd");
  $app->plugin("Systemd" => {config_map => {...}, service_file => "..."});

Used to register the plugin in your application. The following options are
otional:

=over 2

=item * config_map

The C must be a hash-ref and will be I with the
L attribute. Example:

  $app->plugin(Systemd => {
    config_map => {
      # Add your own custom environment variables. The empty quotes means
      # that the environment variable should be read as a string.
      database => {
        url => sub { (MYAPP_DB_URL => "") },
      },
      hypnotoad => {
        # Remove support for the default MOJO_SERVER_ACCEPTS environment
        # variable
        accepts => undef,

        # Change the environment variable from MOJO_LISTEN and
        # the regexp to split the environment variable into a list
        listen  => sub { (MYAPP_LISTEN => [qr{[,\s]}]) },
      }
    }
  });

=item * service_file

Defaults to the environment variable C and I required
if C is set. Must be a full path to where your service file is
located. See L for example.

=back

=head1 AUTHOR

Jan Henning Thorsen

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2019, Jan Henning Thorsen.

This program is free software, you can redistribute it and/or modify it under
the terms of the Artistic License version 2.0.

=head1 SEE ALSO

L, L.

=cut