Minimal LDAP server load-balancing
Net::LDAP provide a way to have more than one LDAP server, this permits to have a fallback. However it tries servers always in the same order. This has some issues:
- only one server is used
- when the first server is down, all LDAP connections are slowed down to wait for first failure
Design proposition
This should be pushed to Lemonldap::NG::Portal::Lib::Net::LDAP and Apache::Session::Browseable.
our %knownDown;
our %knownLdapServerStrings;
sub sortDead {
return 1 if $knownDown{$a} and !$knownDown{$b};
return -1 if $knownDown{$b} and !$knownDown{$a};
return 0;
}
# ...
sub new {
# ...
$knownLdapServerStrings{$conf->ldapServer} ||= [ split( /\s+/, $conf->ldapServer ) || 'localhost' ];
# Simple round-robbin if asked
if ($conf->{ldapRoundRobbin}) {
my $last = shift @{ $knownLdapServerStrings{$conf->ldapServer} };
push @{ $knownLdapServerStrings{$conf->ldapServer} }, $last;
}
# Push server which have failed to the end of the list
my @uris = sort pushDeadToEnd @uris;
my $first = $uris[0];
# ... create LDAP object using \@uris
# Update knownDone list:
# The server chosen by Net::LDAP is up
delete $knownDown{ $self->{net_ldap_uri} };
# If Net::LDAP changed, this means that first LDAP is down
if ( $self->{net_ldap_uri} != $first ) {
$knownDown{ $first } = 1;
}
# ...
}
@clement_oudot, @maxbes: what do you think ?