LCFG Core: Resource import and export

As part of porting the LCFG client to the new core libraries the qxprof and sxprof utilities have been updated. This has led to the development of a new high-level LCFG::Client::Resources Perl library which can be used to import, merge and export resources in all the various required forms. The intention is that eventually all code which uses the LCFG::Resources Perl library (in particular the LCFG::Component framework) will be updated to use this new library. The new library provides a very similar set of functionality and will appear familiar but I’ve taken the opportunity to improve some of the more awkward parts. Here’s a simple example taken from the perldoc:

# Load client resources from DB
my $res1 = LCFG::Client::Resources::LoadProfile("mynode","client");

# Import client resources from environment variables
my $res2 = LCFG::Client::Resources::Import("client");

# Merge two sets of resources
my $res3 = LCFG::Client::Resources::Merge( $res1, $res2 );

# Save the result as a status file
LCFG::Client::Resources::SaveState( "client", $res3 );

The library can import resources from: Berkeley DB, status files, override files, shell environment and explicit resource specification strings. It can export resources as status files, in a form that can be evaluated in the shell environment and also in various terse and verbose forms (e.g. the output styles for qxprof).

The LCFG::Resources library provides access to resources via a reference to a hash which is structured something like:

{
   'sysinfo' => {
                 'os_id_full' => {
                                  'DERIVE' => '/var/lcfg/conf/server/releases/develop/core/include/lcfg/defaults/sysinfo.h:42',
                                  'VALUE' => 'sl74',
                                  'TYPE' => undef,
                                  'CONTEXT' => undef
                                 },
                 'path_lcfgconf' => {
                                  'DERIVE' => '/var/lcfg/conf/server/releases/develop/core/include/lcfg/defaults/sysinfo.h:100',
                                  'VALUE' => '/var/lcfg/conf',
                                  'TYPE' => undef,
                                  'CONTEXT' => undef
                                 },
                }
}

The top level key is the component name, the second level is the resource name and the third level is the name of the resource attribute (e.g. VALUE or TYPE ).

The new LCFG::Client::Resources library takes a similar approach with the top level key being the component name but the value for that key is a reference to a LCFG::Profile::Component object. Resource objects can then be accessed by using the find_resource method which returns a reference to a LCFG::Resource object. For example:

my $res = LCFG::Client::Resources::LoadProfile("mynode","sysinfo");

my $sysinfo = $res->{sysinfo};

my $os_id_full = $sysinfo->find_resource('os_id_full');

say $os_id_full->value;

Users of the qxprof and sxprof utilities should not notice any differences but hopefully the changes will be appreciated by those developing new code.

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