Re: NFS Kernel server inside a container

[Martin Fick <mogulguy-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>]

--- On Wed, 5/19/10, Daniel Lezcano <daniel.lezcano-GANU6spQydw@public.gmane.org> wrote:

> > I was wondering if it is possible to run an NFS kernel
> server inside a linux container?
> >
> > I tried setting one up on a debian (vserver enabled)
> kernel, and it seems to start the portmap, rpc.statd,
> rpc.idmapd rpc.mountd daemons inside the container, but I
> cannot seem to mount the filesystem from a client.  I
> do get the following error message on server startup:
> >
> >    FATAL: Could not load
> /lib/modules/2.6.32-trunk-vserver-686/modules.dep: No such
> file or directory
> >
> >
> > When trying to mount on the client, after blocking on
> the mount for a while, I get:
> >
> >    mount.nfs: mount system call failed
> >    
> 
> It may be possible your network configuration is not
> correct regarding 
> the nfs server access. Can you ping the nfs server from the
> container ?
> 
> > Any thoughts?  Has anyone else done this? 
> Should this be possible in the first place?  Thanks,
> >    
> 
> I thought NFS was isolated through the mount namespace.
> 
> I have a nfs server on 172.20.0.1 exporting "/home".
> 
> On my host (IP 172.20.0.166), I mounted /home via nfs
> 
> I created a debian system container with its own rootfs and
> network. 
> Started it. As expected, the nfs mount point is unmounted
> as it does not 
> belong to the rootfs, and then I remounted /home from my
> container (IP 
> 172.20.0.42). This mount point is private to the container
> and not 
> accessible from the other containers.
> 
> This is what you want to do ? Or did I miss something ?

It sounds like you did an NFS client mount inside a
container. I am actually trying to do the reverse, I
would like to do kernel server exports from within
a container.  Specifically, I would like to have
several data partitions replicated with drbd and to
be able to export these partitions via NFS 
independently from different containers with
different IPs.  

So, for example, from 2 hosts, I might have 6 NFS 
partitions to export and during normal operation
I would expect each host to make 3 of the 
partitions primary via drbd and to then to
each launch three containers each with separate 
IPs which will individually export the 3 different 
drbd partitions via NFS.  For failover or load 
balancing, it should then be able to shut down
any individual container on one host and bring it
up on the other host without affecting the other
exports.

Thanks,

-Martin