Provided by: libpoet-perl_0.13-2_all 
NAME
Poet::Conf -- Poet configuration
SYNOPSIS
# In a script...
use Poet::Script qw($conf);
# In a module...
use Poet qw($conf);
# $conf is automatically available in Mason components
# then...
my $value = $conf->get('key', 'default');
my $value = $conf->get_or_die('key');
my $listref = $conf->get_list('key', ['default']);
my $hashref = $conf->get_hash('key', {'default' => 5});
my $bool = $conf->get_boolean('key');
my @keys = grep { /^foo\./ } $conf->get_keys;
my $hash = $conf->as_hash;
print $conf->as_string;
{
my $lex = $conf->set_local({'key' => 'new_value'});
# key has new_value inside this scope only
}
DESCRIPTION
The Poet::Conf object gives access to the current environment's configuration, read from
configuration files in the conf/ subdirectory.
CONFIGURATION FILES
Poet configuration files are found in the conf/ subdirectory of the environment root:
conf/
global.cfg
global/
something.cfg
something_else.cfg
...
layer/
development.cfg
production.cfg
...
local.cfg
$ENV{POET_EXTRA_CONF_FILE}
The files are read and merged in the following order, with later files taking precedence
over earlier files. None of the files have to exist except "local.cfg".
• "global.cfg" contains various settings for the environment, typically checked into
version control. Having a single file is fine for a simple site and a single
developer, but if this gets too unwieldy, see global/ below.
• The "global/" directory contains multiple .cfg files, all of which are read in
alphabetical order. This is an alternative to "global.cfg" when the latter gets too
crowded and you have multiple developers making simultaneous changes. It is an error
for two global files to set the same key.
• The "layer/" directory contains version-controlled files specific to layers, e.g.
"development.cfg" and "production.cfg". Only one of these files will be active at a
time, depending on the current layer (as set in "local.cfg").
• "local.cfg" contains settings for this particular instance of the environment. It is
not checked into version control. local.cfg must exist and must contain at least the
layer, e.g.
layer: development
• If $ENV{POET_EXTRA_CONF_FILE} is defined when configuration initializes, it is read as
an extra conf file whose values override all others.
CONFIGURATION FORMAT
Basic conf file format is YAML <http://www.yaml.org/>, e.g.
cache:
defaults:
driver: Memcached
servers: ["10.0.0.15:11211", "10.0.0.15:11212"]
log:
defaults:
level: info
output: poet.log
layout: "%d{dd/MMM/yyyy:HH:mm:ss.SS} [%p] %c - %m - %F:%L - %P%n"
Interpolation - referring to other entries
Conf entries can refer to other entries via the syntax "${key}". For example:
# conf file
foo: 5
bar: "The number ${foo}"
baz: ${bar}00
# then
$conf->get('foo')
=> 5
$conf->get('bar')
=> "The number 5"
$conf->get('baz')
=> "The number 500"
The key must exist or a fatal error will occur.
There is a single built-in entry, "root_dir", containing the root directory of the
environment that you can use in other entries, e.g.
cache:
defaults:
driver: File
root_dir: ${root_dir}/data/cache
Dot notation for hash access
Conf entries can use dot (".") notation to refer to hash entries. e.g. this
foo.bar.baz: 5
is the same as
foo:
bar:
baz: 5
The dot notation is especially useful for overriding individual hash elements from higher
precedence config files. For example, if in "global/cache.cfg" you have
cache:
defaults:
driver: File
root_dir: $root/data/cache
depth: 3
and in local.cfg you have
cache.defaults.depth: 2
then only "depth" will be overridden; the "driver" and "root_dir" will remain as they were
set in "global/cache.cfg". If instead local.cfg had
cache:
defaults:
depth: 3
then this would completely replace the entire hash under "cache".
OBTAINING $conf SINGLETON
In a script:
use Poet::Script qw($conf);
In a module:
use Poet qw($conf);
$conf is automatically available in components.
You can also get it via
my $conf = Poet::Environment->current_env->conf;
METHODS
Methods for getting conf values
get (key[, default])
my $value = $conf->get('key' => 'default');
Get key from configuration. If key is unavailable, return the default, or undef if no
default is given.
The return value may be a scalar, list reference, or hash reference, though we
recommend using "get_list" and "get_hash" if you expect a list or hash.
key can contain dot notation to refer to hash entries. e.g. these are equivalent:
$conf->get('foo.bar.baz');
$conf->get_hash('foo')->{bar}->{baz};
get_or_die (key)
my $value = $conf->get_or_die('key');
Get key from configuration. If key is unavailable, throw a fatal error.
get_list (key[, default])
my $listref = $conf->get_list('key', ['default']);
Get key from configuration. If the value is not a list reference, throw an error.
If key is unavailable, return the default, or an empty list reference if no default is
given.
get_hash (key[, default])
my $hashref = $conf->get_hash('key', {'default' => 5});
Get key from configuration. If the value is not a hash reference, throw an error.
If key is unavailable, return the default, or an empty hash reference if no default is
given.
get_boolean (key)
my $bool = $conf->get_boolean('key');
Get key from configuration. Return 1 if the value represents true ("1", "t", "true",
"y", "yes") and 0 if the value represents false ("0", "f", "false", "n", "no") or is
not present in configuration. These are case insensitive matches. Throws an error if
there is a value that is a reference or does not match one of the valid options.
get_secure (key)
my $password = $conf->get_secure('secret_password');
Get key from a separate, non-version-controlled, secure config file; if it cannot be
found, then fallback to normal config. Useful for passwords, encryption keys, etc.
that might be ok in normal config on development, but ought to be secure on
production.
The location of the secure config file is determined by config entry
conf.secure_conf_file; it defaults to "conf/secure.cfg". The file is in plain YAML
format, with no interpolation or dot notation.
Other methods
layer
Returns the current layer, as determined from "local.cfg".
is_development
Boolean; returns true iff the current layer is 'development'.
is_live
Boolean; the opposte of "is_development".
get_keys
my @keys = sort $conf->get_keys;
Return a list of all keys in configuration.
as_hash
my $hash = $conf->as_hash;
Return a hash reference mapping keys to their value as returned by "$conf->get".
as_string
print $conf->as_string;
Return a printable representation of the keys and values.
set_local
my $lex = $conf->set_local({key => 'value', ...});
Temporarily set each key to value. The original value will be restored when $lex goes
out of scope.
This is intended for specialized use in unit tests and development tools, NOT for
production code. Setting and resetting of configuration values will make it much more
difficult to read and debug code!
generate_dynamic_config
$conf->generate_dynamic_config();
This method can be used to dynamically generate configuration files for external
software (e.g. Apache, nginx, logrotate). It uses MasonX::ProcessDir to process Mason
templates in "conf/dynamic" and generate destination files in "data/conf/dynamic".
For example, if "conf/dynamic/httpd.conf.mc" contains an Apache configuration file
with Mason dynamic elements, this method will generate a static configuration file in
"data/conf/dynamic/httpd.conf.mc", which you can then feed directly into Apache.
MODIFIABLE METHODS
These methods are not intended to be called externally, but may be useful to override or
modify with method modifiers in subclasses. Their APIs will be kept as stable as possible.
read_conf_data
This is the main method that finds and parses conf files and returns a hash of conf
keys to values. You can modify this to dynamically compute certain conf keys:
override 'read_conf_data' => sub {
my $hash = super();
$hash->{complex_key} = ...;
return $hash;
};
or to completely override how Poet gets its configuration:
override 'read_conf_data' => sub {
return {
some_conf_key => 'some conf value',
...
};
};
initial_conf_data
Returns a hash with initial configuration data before any conf files have been merged
in. By default, just contains
( root => '/path/to/root' )
_build_layer
Determines the current layer before "read_conf" is called. By default, looks for a
"layer" key in "local.cfg".
_build_is_development
Determines the value of "is_development", and subsequently its opposite "is_live". By
default, true iff layer == 'development'.
ordered_conf_files
Returns a list of conf files to read in order from lowest to highest precedence. You
can modify this to insert an additional file, e.g.
override 'ordered_conf_files' => sub {
my @list = super();
return (@list, '/path/to/important.cfg');
};
read_conf_file ($file)
Read a single conf $file and return its hash representation. You can modify this to
use a conf format other than YAML, e.g.
use Config::INI;
override 'read_conf_file' => sub {
my ($self, $file) = @_;
return Config::INI::Reader->read_file($file);
};
merge_conf_data ($current_data, $new_data, $file)
Merge $new_data from $file into $current_data. $new_data and $current_data are both
hashrefs, and $current_data will be the empty hash for the first file. By default,
this just uses Perl's built-in hash merging with values from $new_data taking
precedence.
CREDITS
The ideas of merging multiple conf files and variable interpolation came from
YAML::AppConfig.
SEE ALSO
Poet
AUTHOR
Jonathan Swartz <swartz@pobox.com>
COPYRIGHT AND LICENSE
This software is copyright (c) 2012 by Jonathan Swartz.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.