[lxc-devel] Restarting snmp service on the host, shutdown snmp on the guest.

[Jean-Philippe Menil]

Hi,

i've just found something that is being anoying me:

when i restart the snmpd daemon on my host, it shutdown the snmpd daemon 
on my container.

The host is a debian squeeze, with a 2.6.37 kernel, and the version 
0.7.3-1  packaged from debian.
Guest are debian squeeze too.

On the host:
root at suntory:~# ps aux | grep snmp
snmp     11747  0.0  0.0  42768  4948 ?        S    16:52   0:00 
/usr/sbin/snmpd -LS6d -Lf /dev/null -u snmp -I -smux -p 
/var/run/snmpd.pid 172.20.6.33
snmp     11752  0.0  0.0  42728  4936 ?        S    16:52   0:00 
/usr/sbin/snmpd -LS6d -Lf /dev/null -u snmp -I -smux -p 
/var/run/snmpd.pid 172.26.0.56
snmp     11804  0.0  0.0  42724  4932 ?        S    16:54   0:00 
/usr/sbin/snmpd -LS6d -Lf /dev/null -u snmp -I -smux -p 
/var/run/snmpd.pid 172.26.0.51
snmp     11820  0.0  0.0  42840  4936 ?        S    16:54   0:00 
/usr/sbin/snmpd -LS6d -Lf /dev/null -u snmp -I -smux -p 
/var/run/snmpd.pid 172.26.0.46
snmp     11873  0.0  0.0  42612  4592 ?        S    16:55   0:00 
/usr/sbin/snmpd -LS6d -Lf /dev/null -u snmp -I -smux -p 
/var/run/snmpd.pid 172.26.0.21
root     12789  0.0  0.0   9660   840 pts/5    S+   17:02   0:00 grep snmp
root at suntory:~# /etc/init.d/snmpd restart
Restarting network management services: snmpd.
root at suntory:~# ps aux | grep snmp
snmp     12800  1.0  0.0  42612  4552 ?        S    17:03   0:00 
/usr/sbin/snmpd -LS6d -Lf /dev/null -u snmp -I -smux -p 
/var/run/snmpd.pid 172.20.6.33
root     12802  0.0  0.0   9660   840 pts/5    S+   17:03   0:00 grep snmp
root at suntory:~#

Where the host, is the one with the 172.20.6.33 ip address.

Here is config file of a guest:

lxc.utsname = ***container-name***

lxc.tty = 4
lxc.pts = 1024
lxc.rootfs = /var/lib/lxc/***container-name***/rootfs

## Restrict capabilities
lxc.cap.drop = audit_control audit_write fsetid ipc_lock ipc_owner lease 
linux_immutable mac_admin mac_override mac_admin mknod setfcap setpcap 
sys_admin sys_boot sys_module sys_nice sys_pacct sys_ptrace sys_rawio 
sys_resource sys_time sys_tty_config

lxc.cgroup.devices.deny = a
# /dev/null and zero
lxc.cgroup.devices.allow = c 1:3 rwm
lxc.cgroup.devices.allow = c 1:5 rwm
# consoles
lxc.cgroup.devices.allow = c 5:1 rwm
lxc.cgroup.devices.allow = c 5:0 rwm
lxc.cgroup.devices.allow = c 4:0 rwm
lxc.cgroup.devices.allow = c 4:1 rwm
# /dev/{,u}random
lxc.cgroup.devices.allow = c 1:9 rwm
lxc.cgroup.devices.allow = c 1:8 rwm
lxc.cgroup.devices.allow = c 136:* rwm
lxc.cgroup.devices.allow = c 5:2 rwm
# rtc
lxc.cgroup.devices.allow = c 254:0 rwm

# mounts point
lxc.mount.entry=proc /var/lib/lxc/***container-name***/rootfs/proc proc 
nodev,noexec,nosuid 0 0
lxc.mount.entry=devpts /var/lib/lxc/***container-name***/rootfs/dev/pts 
devpts defaults 0 0
lxc.mount.entry=sysfs /var/lib/lxc/***container-name***/rootfs/sys sysfs 
defaults  0 0
lxc.mount.entry=tmpfs /var/lib/lxc/***container-name***/rootfs/dev/shm 
tmpfs defaults 0 0

#### network
lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = **bridge**
lxc.network.name = eth0
lxc.network.mtu = 1500
lxc.network.hwaddr = XX:XX:XX:XX:XX:XX
lxc.network.veth.pair = letu2-lmb-clus

I see that, in debian, the init.d script for snmp contains the following
stop)
     echo -n "Stopping network management services:"
     start-stop-daemon --quiet --stop --oknodo --exec /usr/sbin/snmpd

So it's not based on the pid of the process, but on the executable file.

Is there a solution to bypass this problem, that i'm not aware of?

Many thanks.

Regards.