Allow dracut use with ltsp-client-core

[Rainer Stumbaum]

Hi Vagrant,
can you please change the dependancy from initramfs-tools to linux-initramfs-tool. This should allow to use dracut as well as initramfs-tools to provide the necessary initramfs for LTSP.

Thanks
Rainer

[Rainer Stumbaum (stumbaumr)]

This is related to make LTSP via NFSv4 possible and related to this bug
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=409271

[Vagrant Cascadian (vagrantc)]

On 2015-10-26, Rainer Stumbaum <email address hidden> wrote:
> can you please change the dependancy from initramfs-tools to
> linux-initramfs-tool. This should allow to use dracut as well as
> initramfs-tools to provide the necessary initramfs for LTSP.

Currently on Debian and Ubuntu, initramfs-tools hooks are used to set up
the root filesystem with aufs/overlay/overlayfs, so it's not a simple
matter of changing the dependecy; it requires adding similar hooks for
use with dracut.

Would like to have support for dracut...

live well,
  vagrant

[Rainer Stumbaum (stumbaumr)]

I already had it running in a test setup:
- apt-get install dracut-network
- Modify /etc/dracut.conf - Add filesystems+="aufs"
- Build image: dracut -m "network base aufs" --xz --force --keep /boot/initrd.img-3.2.0-4-amd64
- Modify pxelinux.cfg/default: append ro initrd=initrd.img-3.2.0-4-amd64 init=/sbin/init-ltsp ro rd.break=pre-pivot root=nfs4 aufs vmwgfx.enable_fbdev=1 nfs.nfs4_disable_idmapping=1 vga=0x317
- At least mounting /rofs using NFSv4 was working
- But then I hit bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=676883

And this was where I stopped...

Interesting dracut files:
/etc/dracut.conf
/lib/dracut-lib.sh (setdebug)
/usr/lib/dracut/modules.d/90aufs/module-setup.sh
/usr/lib/dracut/modules.d/90aufs/aufs-mount.sh
/lib/dracut/hooks/pre-pivot/10-aufs-mount.sh

Interesting dracut kernel parameters
rd.break=pre-pivot
rd.debug

[Alkis Georgopoulos (alkisg)]

We could create a /usr/share/ltsp/init-ltsp.d/00-overlay script that would apply a tmpfs overlay over all root /dirs, like /bin, /etc, /usr...
That way / will still be read-only, but all the other dirs and files in the file system will be writeable, so it should work in most use cases.

That way we can support any initramfs and even initramfs-less systems, as long as they can mount the root read-only without help from ltsp initramfs scripts (and as long as we don't hit other bugs).
E.g. https://fedoraproject.org/wiki/Dracut/Options#NBD should work fine without any LTSP code other than 00-overlay.

[Vagrant Cascadian (vagrantc)]

On 2015-10-28, Alkis Georgopoulos wrote:
> That way we can support any initramfs and even initramfs-less systems,
> as long as they can mount the root read-only without help from ltsp
> initramfs scripts (and as long as we don't hit other bugs).
> E.g. https://fedoraproject.org/wiki/Dracut/Options#NBD should work
> fine without any LTSP code other than 00-overlay.

Reading that, it doesn't sound like dracut supports named NBD exports,
just port-based ones... hopefully that's just a lacking in
documentation... probably not terribly hard to fix.

live well,
  vagrant

[Alkis Georgopoulos (alkisg)]

Just noting that I managed to boot LTSP with dracut in Gentoo (I added the init-ltsp.d/00-overlay script I mentioned above), so it should work in Debian-based distributions as well now.

Testers welcome. :)

[Rainer Stumbaum (stumbaumr)]

Hi again,

in 2015 when I wanted to use NFSv4 it was just playing around with newer NFS versions (back then the RFC was already 15 years old...).

Now it becomes a necessity since we are moving away from NetApp to NFS Ganesha on top of CephFS.

So is dracut/NFSv4 already supported in current versions of LTSP?

Best regards
Rainer

[Alkis Georgopoulos (alkisg)]

Hi Rainer,

LTSP doesn't use launchpad anymore; you can use the upstream bug tracker there:
https://github.com/ltsp/ltsp/issues

For discussions, you can use this one instead:
https://github.com/ltsp/ltsp/discussions

So for example, dracut support is discussed there:
https://github.com/ltsp/ltsp/discussions/197

Let's continue there; or if you prefer to discuss dracut in Debian specifically, you may also open another discussion thread there.

[Alkis Georgopoulos (alkisg)]

Closing old LTSP bugs as they're no longer relevant after LTSP has been rewritten from scratch.