On 02/22/2012 07:23 PM, Perry Myers wrote:
Well, if the network is busted which leads to the bridge rename failing,
wouldn't the fact that the network is broken cause other problems anyhow?

Perry, my point is that we're increasing the chances to get
into these holes. Network is not busted most of the time, but occasionally
there's a glitch and we'd like to stay away from it. I'm sure
you know what I'm talking about.

What if oVirt Node creates ifcfg-ovirt (instead of ifcfg-br0) by default
as part of bringing up the network on each boot (via either DHCP or
kernel args)?

what if admin wants this bonded, or bridgeless, or jumbo frames?
stateless doesn't mean you can't save configuration somewhere on the network, right (could be on engine, could be just on some nfs or http location). if you have a tpm, just encrypt all the data to make sure no one tampered with your config, or if you don't care, just download your config (well, you trust the network to download your image without encryption, so no need to be fanatic i guess).

so in short:
1. pxe boot the image
2. download from known location (kernerl param) the rest of the config you care about, certificates, etc. 3. use tpm for private key (or get the password to keystore in config via kernel parameter if you don't want/have tpm.

I guess my main question is why does stateless implies no saved config for all the various issues


Then vdsm would never need to do this.  This particular step could be
something that is turned on/off only if vdsm is installed so that it
doesn't affect any non-oVirt usages of oVirt Node (Archipel, etc)

* Today there's a supported flow that for nodes with
password, the user is allowed to use the "add host"
scenario. For stateless, it means re-configuring a password
on every boot...

This flow would still be applicable.  We are going to allow setting of
the admin password embedded in the core ISO via an offline process.
Once vdsm is fixed to use a non-root account for installation flow, this
is no longer a problem
This is not exactly vdsm. More like vdsm-bootstrap.

ack


Also, if we (as described above) make registrations persistent across
reboots by changing the registration flow a bit, then the install user
password only need be set for the initial boot anyhow.

Therefore I think as a requirement for stateless oVirt Node, we must
have as a prerequsite removing root account usage for
registration/installation

This is both for vdsm and engine, and I'm not sure it's that trivial.

Understood, but it's a requirement for other things.  There are security
considerations for requiring remote root ssh access as part of your core
infrastructure.  So this needs to be dealt with regardless.

- Other issues

* Local storage; so far we were able to define a local
storage in ovirt node. Stateless will block this ability.

It shouldn't.  The Node should be able to automatically scan locally
attached disks to look for a well defined VG or partition label and
based on that automatically activate/mount

Stateless doesn't imply diskless.  It is a requirement even for
stateless node usage to be able to leverage locally attached disks both
for VM storage and also for Swap.

Still, in a pure disk-less setup you will not have local storage.
See also Mike's answer.

Sure.  If you want diskless specifically and then complain about lack of
swap or local storage for VMs...  then you might not be getting the point :)

That has no bearing on the stateless discussion, except that the first
pass of stateless might not allow config of local disk/swap to start
with.  We might do it incrementally

* Node upgrade; currently it's possible to upgrade a node
from the engine. In stateless it will error, since no where
to d/l the iso file to.

Upgrades are no longer needed with stateless.  To upgrade a stateless
node all you need to do is 'reboot from a newer image'.  i.e. all
upgrades would be done via PXE server image replacement.  So the flow of
'upload ISO to running oVirt Node' is no longer even necessary

This is assuming PXE only use-case. I'm not sure it's the only one.

Nope...

copy oVirt Node 2.2.3 to a USB stick (via ovirt-iso-to-usb-disk)
boot a host with it

Later...

copy oVirt Node 2.2.4 to same USB stick (via ovirt-iso-to-usb-disk)
boot the host with it

Yes, it requires you to touch the USB stick.  If you specifically want
stateless (implying no 'installation' of the Node) and you won't be
using PXE to run, then it involves legwork.

But again, we're not planning to eliminate the current 'install'
methods.  Stateless is in addition to installing to disk, and using the
'iso upload' upgrade method

* Collecting information; core dumps and logging may not
be available due to lack of space? Or will it cause kernel
panic if all space is consumed?

We already provide ability to send kdumps to remote ssh/NFS location and
already provide the ability to use both collectd and rsyslogs to pipe
logs/stats to remote server(s).  Local logs can be set to logrotate to a
reasonable size so that local RAM FS always contains recent log
information for quick triage, but long term historical logging would be
maintained on the rsyslog server

This needs to be co-ordinated with log-collection, as well as the bootstrapping
code.

Yep.  Lots of stuff for vdsm/oVirt Engine team to do in order to meet
this requirement :)

In contrast, making oVirt Node stateless is quite trivial.  Most of the
work here is actually for vdsm and other related utilities (like log
collector)

Perry
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