[ENHANCEMENT] Examine for duplicated MAC addresses when creating new VMs in the Harvester cluster about harvester

[Martin-Weiss]

@irishgordo - true - and I believe having a warning / alert in harvester for "duplicate MAC" might be really good for administrators.. but blocking it completely in the admission controller is something I would not recommend (especially for the restore situation).

[Martin-Weiss]

Please keep in mind that having duplicate MAC addresses is a valid scenario!

Duplicate MAC addresses can happen in case of restores (restore to a new VM name) - in this case the old VM is powered off and the new (restored VM) will have the same MAC address.

And in this scenario duplicate MAC addresses are even valid in case both VMs are running but are connected to different L2 networks. Usecase - restore VM to an isolated environment for testing etc.

The "only" problematic thing might be to run two VMs with identical MAC addresses in the same L2 network.

[irishgordo]

@Martin-Weiss that's a great point 😄

With:

The "only" problematic thing might be to run two VMs with identical MAC addresses in the same L2 network.

I would mention that for "some" network infrastructure/hardware - would likely get alerted / notified that it is happening - so Network Engineers (or other individuals) within an Org would be made aware from the switch/routing level that something is happening with the identical MAC addresses in the same L2 network. Some systems do push notifications, emails, or other means (Slack, Teams, etc.).

Here's an example from my UniFi setup where I've had identical MACs running in VMs on the same L2 network (if I can recall correctly that this was happening when it did 😅 ) and the errors/notifications it would throw:

So maybe at least from that sense, it would be known by notifications/push-alerts/etc. when that was happening at the L2 network level depending on the underlying infrastructure/equipment that was being used. And "possibly" the fix could come from that level as well vs from a Harvester admin side.