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VE mutual dependence [message #34464] Wed, 07 January 2009 19:08 Go to next message
laotse is currently offline  laotse
Messages: 35
Registered: December 2008
Member
Hi there,

is there a standard way to resolve mutual dependences of VE during startup? E.g. a container might host a file-server, which exports file systems, which another container shall import (or DNS, DHCP, ...)

Of course the dependent VE could be marked as not auto-starting and I could chain a script for the rest; which I'll probably do. The question is, whether there is some canonical way to achieve that?

Regards,
- lars.
Re: VE mutual dependence [message #34478 is a reply to message #34464] Fri, 09 January 2009 12:06 Go to previous messageGo to next message
maratrus is currently offline  maratrus
Messages: 1495
Registered: August 2007
Location: Moscow
Senior Member
No, there is no canonical way to achieve that. But if you have any idea feel free to share it (or better implement Smile ).
Re: VE mutual dependence [message #34481 is a reply to message #34478] Fri, 09 January 2009 19:18 Go to previous messageGo to next message
laotse is currently offline  laotse
Messages: 35
Registered: December 2008
Member
Well, for my personal needs I'd simply put up a more or less sequential script.

As a proposal for a canonical way, I'd consider a mechanism like the passes in fstab. If there is some public interest in it, I guess I could implement that - once I have the system out of any severe functional problems.

[Updated on: Fri, 09 January 2009 19:19]

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Re: VE mutual dependence [message #34488 is a reply to message #34464] Mon, 12 January 2009 06:56 Go to previous message
curx
Messages: 739
Registered: February 2006
Location: Nürnberg, Germany
Senior Member

you can use the OpenVZ Action script for a single dependecy mechanism, here using a mount script.

Checks if a container is running, if not, mount script exit with error code greater than 0 and vzctl start is aborted.

#!/bin/bash

#  Copyright (C) 2006-2008 :
#	Thorsten Schifferdecker <tsd@debian.systs.org>
#  	All rights reserved.
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#

#  /usr/share/vzctl/scripts/vps.mount-10-ct-dependency.sh 

# include main vz.conf
VZCONF=/etc/vz/vz.conf
[ -f ${VZCONF} ] || exit 0
. ${VZCONF}

# debug mode in main vz.conf set ?
[ "$DEBUG" == "yes" ] && set -x

# single dependency container id 
CT_DEPEND="`awk -F '"' '/^CT_DEPEND/ { print $2 }' /etc/vz/conf/$VEID.conf`"
[ -f /etc/vz/conf/${CT_DEPEND}.conf ] || exit 0
[ $VEID -ne $CT_DEPEND ] || exit 0

# cycles to check
CHECK_CYCLE=10

# sleep time
SLEEP_TIME=5

LOG_MESSAGE="Container dependency"
__OK="is solved"
__FAILED="has failed"

#
# main
#
for i in ${CHECK_CYCLE} ; do

	# started and running container has beancounters to avoid vzlist
	if [ -d /proc/bc/${CT_DEPEND} ] ; then
		[ $LOGGING == 'yes' ] && echo "`/bin/date +%FT%H:%M:%S%z` vzctl : CT ${VEID} : $LOG_MESSAGE to CT ${VEID} $__OK" >> $LOGFILE
		printf "$LOG_MESSAGE to CT ${VEID} $__OK\n"

		# add checking services, too
		# include service checks

		exit 0
	fi

sleep $SLEEP_TIME
done  

[ ${VERBOSE} -ne 0 ] && printf " to CT ${VEID} $__FAILED\n"
[ $LOGGING == 'yes' ] && printf "`/bin/date +%FT%H:%M:%S%z` vzctl : CT ${VEID} : Error $LOG_MESSAGE to CT ${VEID} $__FAILED\n" >> $LOGFILE
printf "$LOG_MESSAGE $__FAILED\n"

exit 1


save this script to /usr/share/vzctl/scripts/vps.mount-10-ct-dependency.sh and create a symbolic link :

global:
$ ln -s /usr/share/vzctl/scripts/vps.mount-10-ct-dependency.sh /etc/vz/conf/vps.mount

or for single container,m only:
$ ln -s /usr/share/vzctl/scripts/vps.mount-10-ct-dependency.sh /etc/vz/conf/<CTID>.mount

and activate check:

$ echo "CT_DEPEND=\"<CTID_DEPENDS_ON>\"" >> /etc/vz/conf/<CTID>.conf

Bye,
Thorsten
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