Make bootMACAddress optional

[hardys]

User Story

As a user deploying only with virtualmedia I would like to omit bootMACAddress from my BMH definitions, so I can simplify the definition and reduce the pre-requisite information needed from the environment.

Detailed Description

Historically there have been issues which meant Ironic required the bootMACAddress even for non-PXE deployments handled via VirtualMedia (where in theory we shouldn't need any host network information).

Recent discussion on Slack with @dtantsur indicates we may be able to remove this restriction now given changes in Ironic since the original bootMACAddress API decision.

We should identify the relevant Ironic changes which remove the need for this information, then test on baremetal to ensure it's safe to make this field optional, and if so adjust the BMH schema to avoid requiring this information in all cases.

/kind feature

[dtantsur]

Recent discussion on Slack with @dtantsur indicates we may be able to remove this restriction now given changes in Ironic since the original bootMACAddress API decision.

To be more precise, the Redfish driver in Ironic now tries to enroll ports (= NIC's) using Redfish before starting the full inspection. This makes BootMACAddress automatically available to Ironic. Caveats:

1. In rare cases, the EthernetInterface resources are not implemented in Redfish
2. If inspection is disabled, this workaround won't take place.

I have written a proposal https://bugs.launchpad.net/ironic/+bug/2049913 that suggests rethinking the whole inspection process, but I don't have any time to work on it.

[Rozzii]

/triage accepted
I am fine with this, this might cause some initial confusion for some users because the PXE booting will require a field that the Redfish won't + the rare cases @dtantsur mentioned, but I can live with that.

[metal3-io-bot]

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[Rozzii]

/remove-lifecycle stale
/lifecycle frozen