Kir Kolyshkin wrote:
Steve Wray wrote:
Hi there,
Debian uses start-stop-daemon in the init scripts to, for one thing,
stop services.
From the man page:
Note: unless --pidfile is specified, start-stop-daemon behaves similar
to killall(1). start-stop-daemon will scan the process table looking
for any processes which match the process name, uid, and/or gid (if
specified). Any matching process will prevent --start from starting the
daemon. All matching processes will be sent the KILL signal if --stop
is specified. For daemons which have long-lived children which need to
live through a --stop you must specify a pidfile.
For example, nfs-kernel-server does not use --pidfile. It looks for
nfsd processes to kill.
Suppose that the Openvz host and one of its guests were running NFS
and, on the host, one were to run /etc/init.d/nfs-kernel-server stop
As I understand it this would have the side-effect of killing off the
nfsd processes on the guest.
That is right, and this is just one of the reasons why we don't
recommend to run anything (but the needed bare minimum like sshd) on the
host system.
In my case, this isn't practical; I use cfengine to manage and maintain
virtually all of our servers. We have a lot of servers.
In fact, it was cfengine which brought this to my attention; I restarted
it on the openvz host and then started to get nagios alerts about
cfengine not running on any of the guests.
It was at this point that I realised that openvz isn't a virtualisation
environment; its a very *very* sophisticated chroot.
There is a solution and a workaround for the problem. The solution is,
right, to fix bad initscripts. I mean, it's not OpenVZ-specific --
relying on process names is wrong, any user can run a process named nfsd
and it should not be killed.
The workaround is to introduce a feature to hide guests' processes from
the host system. This is implemented in OpenVZ kernels >= 2.6.24 as per
bug #511 (http://bugzilla.openvz.org/511).
Well I look forward to trying this out some time!
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