WAKE_ON_LAN power method cannot power off a node.

[Raphaël Badin]

MAAS needs to be able to power cycle a node to properly function so this WAKE_ON_LAN power method isn't really working (i.e. it requires the node to be manually power cycled to function).

My suggestion, as discussed with the team, is simply to drop "support" for WAKE_ON_LAN in MAAS. (Note that if we do so, we can close bug 1005802.)

[sodre (psodre)]

I think it is a bad idea to take a feature away just to close bug #1005802. There are better solutions there, in particular warning the user that he must install etherwake / wakeonlan for things to work.
Notice that the same is true during testing phase using virsh.

I am biased towards the WOL feature since I am deploying MAAS on a group of low-end hardware where WOL is the only way to power them on. In order to power them off, I usually ssh in and sudo poweroff before returning it to the managed environment.

[Gavin Panella (allenap)]

This isn't just to fix bug #1005802. That's not even the reason we discussed dropping WOL support. It's that we have no way to reliably tell users to power off a machine; it's entirely up to the user to remember to do so. We would need a workflow something like:

- Ask user to power down machine,
- Wait for confirmation that machine has been powered down,
- Release machine back to the pool.

I joked (in person) that an email power type would be as good - i.e. we email the machines owner to ask them to press the power button - and it's not entirely without merit. However, we have enough complexity to support already that we've chosen to not support WOL any more. It's half the interface we need, and is going to be less than that as we progress through this cycle of development.

One bit of hope though: one of our plans for this cycle is to formalise the way to add support for a new piece of hardware, including power control, giving MAAS a plugin-like system for new kit. I imagine it would be possible to reintroduce WOL via that mechanism so that we don't have to support it in "upstream" MAAS. It's all a bit hand-wavy at this point, but you can read our thoughts so far at https://blueprints.launchpad.net/maas/+spec/t-cloud-maas-hardware-enablement.

[sodre (psodre)]

Okay. thanks for the explanation. I hope once the new method comes up there will be an easy way to push WOL on it.

[Christian Reis (kiko)]

FWIW, I don't think lack of the ability to shut down is justification for completely removing WoL. PDUs have a similar issue. And AFAICT it only affects us when we are releasing a node or issuing a user-directed power down, the latter of which is obviously something we could avoid letting the user do.

[David Duffey (dduffey)]

For shutdown, could MAAS in many situations be able to ssh into the host and power it off? It would not work on hung systems or for custom images, but could work in general cases.

Power status could be the same, with either an agent on the host, or pinging the knows address MAAS knows about. It would not catch all cases (hosts that firewall UDP, etc.), but it would work for most cases.

[Blake Rouse (blake-rouse)]

MAAS could but currently it does not place a SSH key on the host, that MAAS holds the private key for. This would also require careful use because if MAAS has an SSH key on all hosts then compromise of the MAAS server would mean compromise of all hosts.

The best way might be to have a little agent on the machine that checks with MAAS periodically to see if it should shutdown. Even that has security issues, but better than MAAS having a private key into the machine. Again this would require an amount of work that might not be practical for just supporting the ability to power off a machine.

[Kai Mast (kai-mast)]

Here is another suggestion. There is IPMID that exposes the IPMI api from the userspace. How about using Wake on Lan to start the machine and then IPMID )or some other daemon that exposes ACPI to the network) for the rest?

[Newell Jensen (newell-jensen)]

The WoL power control capabilities of MAAS have been replaced with the Manual power driver. Marking as Won't Fix as this is no longer relevant.