adding multipathd as extension

[oliverbaehler]

We have started the conversation in Slack already:

• https://taloscommunity.slack.com/archives/CG25RPZNE/p1740658131754019

Let's reiterate the point.

we have recently had an enduser which attempted to use Astra Trident with Netapp. However, they are arguing that they are missing the required iscsi multipathd tools to be able to announce all their storage controllers. (I would say that's true with other enterprise storage solutions as well).

I have discovered there was already an open PR regarding this

The problem with #505 is that it was created without discussing it with the team, and that particular implementation cutting some corners. This seems to be a better implementation, but not complete: https://github.com/bzub/extensions/tree/multipath-tools"

So therefor I would like to start a thread here if that's still something the Talos maintainers are comfortable looking at the possibility to add these iscsi multipathd tools (i can also put some effort into it to make it work)? Or are there any other plans?
We have had already a discussion with the Netapp folks and from my understanding they would love to fully support Talos, but it's not possible with this binary absent. In our case and other cases the users just went with the NFS Implementation from Netapp.

The next steps would be getting approval from the maintainers, to onboard this extension. Then finalizing what bzuz has already done:
main...bzub:extensions:multipath-tools

[smira]

We are happy to get any extension into Talos, as long as it works, and has a test (on Talos side if it's possible to verify that it works to some extent).

The diff you posted is reasonable, I guess there will be some discussion about details, like what should be a persistent storage for it.

[gerhard]

Thank you for kicking this off @oliverbaehler 💪

I am keen to test this out with TrueNAS ElectricEel-24.10.1 iSCSI, and double-check that it behaves as expected for those end-users. I suspect that @mischavandenburg may be interested in this too.