[Config-loader] [Config Loader] Use cases was updated

[Config Loader]

Robert Krimen updated the page Use cases. View the changes below.
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The "basic" C::P::ConfigLoader scenario


User has main config "myapp.conf", and wants to allow local overrides  =

in "myapp_local.conf"


Directory tree
User has a number of files in a directory tree. CL recurses through the  =

tree, loading each file, and inserting it into the config hash with the  =

directory name and the file name as branches in the tree, for instance:

/app
/db
/main.conf

->

$config =3D { app =3D> { db =3D> { main =3D> $file_contents }}}

The contents of local override files could be applied at any point in the  =

tree.

Specific filename


# Load the config directly

my $config =3D Config::Loader->new( file =3D> path/to/config.conf )



path/to/application_home/xyzzy.conf

path/to/application_home/xyzzy_local.conf

path/to/application_home/xyzzy.yml

path/to/application_home/xyzzy_local.yml

...



Base file name

# Guess at possible config files

my $config =3D Config::Loader->new( name =3D> xyzzy, path =3D>  =

path/to/application_home/ )



Using ENV for file location


With the second style of instantiation, Config::JFDI will also lookup  =

$ENV{uc $name . _CONFIG}, etc. for ENV overriding


Filtering which files are loaded

Only load that config files that (eg) pertain to this process' role, or are=
  =

relevant to this particular machine (eg with hostname).


$config =3D Config::Loader->new({
path =3D> '/path/to/load',
load_if =3D> qr/.*_daemon/,
| skip_if =3D> qr/.*_daemon/,
});

load_if and skip_if could accept scalars (eq), regexes, code refs, hash  =

refs (exists), or array refs containing any of the previous (load_if loads  =

and skip_if skips at the first true value).

The matching would be performed against the 'pseudo-path', for instance  =

for './app/db/main.yaml', the matching would be performed  =

against 'app.db.main'.

Should skip_if be called load_unless instead, for concistency with merge_if=
  =

/ merge_unless below?




Filtering which files are merged (local overrides)

The user may want to control which files are intended for merging, instead  =

of loading:


$config =3D Config::Loader->new({
path =3D> '/path/to/load',


merge_if =3D> qr/.*_local/,


| merge_unless =3D> qr/.*_local/,
});

To be considered for merging, the file would first have to be have passed  =

the load_if and skip_if checks.

Now for something different


Config::Loader::Plugin::
Config::Loader::Stack # Each read configuration gets pushed onto this
Config::Loader::Read::
Config::Loader::Read::Any (... using Config::Any)
Config::Loader::Read::General (... using Config::General)

my $loader =3D Config::Loader->new
$loader->setup_reader('Any' =3D> { ... Any setup (name, _local suffix, look=
  =

at $ENV, etc)... })
$loader->setup_reader('General')
$loader->setup_parser('Substitute') # Does C::P::ConfigLoader style  =

substituting

$loader->read({ ... A hash containing default values ... })
$loader->read( 'any:path/to/config/directory' )
$loader->read( 'path/to/general-style.cnf' )
$loader->read( 'general:unknown-extension.txt' )

my $config =3D $loader->load # Does parsing and merging

Now the idea above is that Config::Loader just provides an API for people  =

to use. We should provide Config::Loader::Simple for 90% of the people that=
  =

don't care how it's done, they just what something loaded from disk.

The advantage of the above approach is that people can easily cobble  =

together their own config loader in MyApplication::Config namespace using  =

the Config::Loader API

The above 1-7 ideas can be subsumed as custom readers/parser/mergers or  =

plugins overloading the read/parse/merge phase.




Go to page: Use cases


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