Allow to set replica for MongoDB configuration backend

Sent by Albéric de Pertat:

I am currently building a three nodes cluster with LemonLDAP::NG 1.9 (Ubuntu 14.04) and storing configuration in a MongoDB cluster (one instance on each LL::NG node, in a replica set). I have been following the official documentation (http://lemonldap-ng.org/documentation/1.9/mongodbconfbackend), which is OK for one node, but not for a cluster.

First, in lemonldap-ng.ini I need to declare the host MongoDB-URI style :

 host = mongodb://portail1:27017,portail2:27017,portail3:27017
{code}

But then, lmConfEditor will not work :
{code}
 $ /usr/share/lemonldap-ng/bin/lmConfigEditor
 Running as uid 33 and gid 33 0
 MongoDB::SelectionError: No readable server available for matching read
 preference primary. MongoDB server status:
 Topology type: Sharded; Member status:
{code}

This is because the MongoDB configuration backend does not allow us to
specify the replica set. I have modified Lemonldap/NG/Common/Conf/MongoDB.pm like this :
{code}
 --- MongoDB.pm.orig     2016-03-24 16:42:43.287704391 +0100
 +++ MongoDB.pm  2016-03-24 16:43:11.395705731 +0100
 @@ -28,7 +28,7 @@
     return $self->{_mongoDB} if ( $self->{_mongoDB} );
     my $conn_args = {};
     foreach my $w (
 -        qw(host auth_mechanism auth_mechanism_properties
 connect_timeout_ms db_name port ssl username password)
 +        qw(host auth_mechanism auth_mechanism_properties
 connect_timeout_ms db_name port ssl username password replica
 _set_name)
       )
     {
         $conn_args->{$w} = $self->{$w} if ( defined $self->{$w} );
{code}

I just need to set the replica set name in lemonldap-ng.ini :
{code}
 replica_set_name = llng

And it should work.

This is a quick and dirty hack as I am sure the MongoDB backend would surely benefit from a number of specific options that I do not know of. Anyway, keep up the good work !