Machine resource discovery does not work for PPC

thanks for this. could you please use https://maas.io/docs/how-to-review-and-report-bugs to get us a few more pieces of information? not sure how to triage this one atm.

Context:

* Maas via Debs:
maas-cli/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed]
maas-common/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed]
maas-dhcp/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed]
maas-dns/jammy 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all
maas-proxy/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed]
maas-rack-controller/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed]
maas-region-api/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed,automatic]
maas-region-controller/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed]
maas/jammy,now 1:3.3.4-13189-g.f88272d1e-0ubuntu1~22.04.1 all [installed]

* CLI/UI/API?
Irrelevant, since the result is from a commission script.

* What happens?
Commissioning or enlisting a POWER machine does not fill the machine info, as exposed in the GUI as "Hardware Information" on the "Summary" page or or the "hardware_info" json part of 'maas $USER machine read $MACHINE' :

  "hardware_info": {
    "system_vendor": "Unknown",
    "system_product": "Unknown",
    "system_family": "Unknown",
    "system_version": "Unknown",
    "system_sku": "Unknown",
    "system_serial": "Unknown",
    "cpu_model": "POWER8 (architected), altivec supported",
    "mainboard_vendor": "Unknown",
    "mainboard_product": "Unknown",
    "mainboard_serial": "Unknown",
    "mainboard_version": "Unknown",
    "mainboard_firmware_vendor": "Unknown",
    "mainboard_firmware_date": "Unknown",
    "mainboard_firmware_version": "Unknown",
    "chassis_vendor": "Unknown",
    "chassis_type": "Unknown",
    "chassis_serial": "Unknown",
    "chassis_version": "Unknown"
  },

* How to reproduce?
Long way: Commission a PowerPC machine and look at the results.
Short way:
Execute "/usr/share/maas/machine-resources/ppc64el" on a PowerPC host.
The JSON output of that contains:

        "system": {
            "uuid": "",
            "vendor": "",
            "product": "",
            "family": "",
            "version": "",
            "sku": "",
            "serial": "",
            "type": "physical",
            "firmware": null,
            "chassis": null,
            "motherboard": null
        }

In fact, the issue seems to be with the underlying `lxd/resources` script used, which relies on DMI, which in turn, does not exist on POWER.
LSHW, however works fine, as it uses the POWER device tree.

I merely reported here as Anton Troyanov asked me to on the Discourse.

I attach logs from a machine this happened to plus maas logs of tha time..

Thank you for the very detailed bug report!

I am currently in touch with LXD team, we will decide if we should make a change to the LXD package or handle this case inside MAAS by taking values from lshw data.

For the reference, Stéphane mentioned that DMI data might be not available on all the arches
https://github.com/canonical/lxd/issues/7189#issuecomment-613749832

I've reported https://github.com/canonical/lxd/issues/12112 to get the input from the team about a proposed change to use `lshw`'s output rather than parsing `/sys/class/dmi/id` directly.

Welcome!

I think the tough part is that PPC devicetree is more structured but also a bit harder to parse.
It is more versatile, tho.

Once the linked LXD issue is fixed, update the LXD library in MAAS.