LDAP health check daemon

ldap-health-check.pl

#!/usr/bin/perl

=head1 NAME

ldap-health-check

=head1 INSTALL

First, put this script into /usr/local/bin/ and make it executable.

Second, prepare the following service file as
/etc/systemd/system/ldap-health-check.service.

  [Unit]
  Description = ldap-health-check daemon

  [Service]
  ExecStart = /usr/local/bin/ldap-health-check --conffile /etc/postfix/your-ldap-config.cf
  Type = simple
  Restart = always
  StartLimitBurst = 1

  [Install]
  RequiredBy = postfix.service

Finally, configure your cron daemon to make postfix start
periodically.

=head1 AUTHOR

TSUCHIYA Masatoshi <tsuchm@gmail.com>

=head1 LICENSE

GPL3.

=cut

use English qw/ $PROGRAM_NAME $PID $UID /;
use File::Basename qw/ basename /;
use Getopt::Long;
use Net::LDAP;
use Sys::Syslog qw/ LOG_MAIL LOG_INFO LOG_NDELAY /;
use User::pwent;
use POSIX qw/ setgid setuid /;
use strict;

our @SERVER;
our $BINDDN;
our $BINDPW;
our $BASEDN;
our $INTERVAL = 30;
our $DEBUG;

&GetOptions( 'conffile=s' => sub { &readconffile($_[1]); },
	     'server=s@'  => \@SERVER,
	     'binddn=s'   => \$BINDDN,
	     'bindpw=s'   => \$BINDPW,
	     'basedn=s'   => \$BASEDN,
	     'interval=i' => \$INTERVAL,
	     'debug!'     => \$DEBUG );

&main();
sub main {
    if( $UID == 0 ){
	my $pw = getpwnam('nobody') or die;
	&setgid( $pw->gid );
	&setuid( $pw->uid );
    }
    sleep $INTERVAL while &check();
    exit 1;
}

sub check {
    my $ldap;
    for my $server ( @SERVER ){
	last if ( $ldap = Net::LDAP->new( $server ) );
    }
    unless( $ldap ){
	&syslog( 'LDAP connection error' );
	return 0;
    }
    my $msg = $BINDDN ? $ldap->bind( $BINDDN, password => $BINDPW ) : $ldap->bind();
    if( $msg->code ){
	&syslog( 'LDAP bind error: dn=%s, code=%s, reason=%s', $BINDDN, $msg->code, $msg->error );
	return 0;
    }
    $msg = $ldap->search( filter => '(objectClass=*)', base => $BASEDN, scope => 'base' );
    if( $msg->code ){
	&syslog( 'LDAP search error: dn=%s, code=%s, reason=%s', $BASEDN, $msg->code, $msg->error );
	0;
    } else {
	&syslog( 'LDAP search success: dn=%s', $BASEDN );
	1;
    }
}

INIT {
    &Sys::Syslog::openlog( sprintf( '%s[%d]', &basename($PROGRAM_NAME), $PID ), LOG_NDELAY, LOG_MAIL );
}

sub syslog {
    my $message = sprintf( shift, @_ );
    &Sys::Syslog::syslog( LOG_INFO, $message );
    print 'DEBUG: ', $message, "\n" if $DEBUG;
}

END {
    &Sys::Syslog::closelog();
}

sub readconffile {
    my( $file ) = @_;
    if( open( my $fh, '<:bytes', $file ) ){
	while ( <$fh> ) {
	    s/\s+\Z//;
	    if( s/\Abind_dn=// ){
		$BINDDN = $_;
	    } elsif( s/\Abind_pw=// ){
		$BINDPW = $_;
	    } elsif( s/\Asearch_base=// ){
		s/%d/%s/;
		$BASEDN = $_;
	    } elsif( s/\Aserver_host=// ){
		@SERVER = ( $_ );
	    }
	}
	close $fh;
    }
}