Expose flatcar-install OEM parameter

[MLNW]

By exposing this parameter it is possible to install OEM specific software during the flatcar-install invocation.

Testing

I installed a Kubernetes cluster on vSphere VMs and used the newly exposed flag to install the vmware OEM files. Now vSphere no longer complains that the vSphere tools are not installed and it is possible to see the assigned hostname and IPs in the vSphere UI. This also enables the vSphere Terraform provider to wait for IP assignment.

When using cached_install = true Matchbox also needs to serve these files otherwise the installer.service fails:

https://${channel}.release.flatcar-linux.net/amd64-usr/${version}/flatcar_production_${oem_type}_image.bin.bz2
https://${channel}.release.flatcar-linux.net/amd64-usr/${version}/flatcar_production_${oem_type}_image.bin.bz2.sig

[MLNW]

@dghubble the last part of above description complicates the merge of this PR. I would propose adding an option to the matchbox/get-flatcar script that downloads all provided oem_type files. Then users may deploy Matchbox with a supported set of oem_types which may be used in conjunction with the newly exposed flag when deploying a baremetal cluster with Typhoon. If you agree I will create a PR for that as well.

[dghubble]

Setting the flatcar-linux OEM flag is ok. I don't use VMWare or the others so I won't validate them, but this change can just be oriented around allowing the parameter to be set. Its up to Flatcar Linux what that does, since I don't want OEM specific features creeping into the distro itself.

Can you also dig up more info from the Flatcar Linux folks about the OEMs they support / will support?

[dghubble]

Can you include the list of valid Flatcar OEMs in the description, like (e.g. a, b, c) and link to Flatcar Linux docs

[MLNW]

I wrote some more documentation here. PTAL and let me know if its okay.

[dghubble]

I don't think the Matchbox script needs an update. Folks wanting OEM specific stuff can download it.

[MLNW]

I don't think the Matchbox script needs an update. Folks wanting OEM specific stuff can download it.

We use a systemd unit like this:

    - name: "download-flatcar.service"
      enabled: true
      contents: |
        [Unit]
        Description=Download Flatcar image
        Wants=systemd-resolved.service
        After=clone-matchbox.service
        Before=matchbox.service

        [Service]
        Type=oneshot
        RemainAfterExit=true

        ExecStart=/usr/bin/bash -c '/usr/bin/test -d /opt/matchbox.opt/matchbox/assets || /opt/matchbox/scripts/get-flatcar ${flatcar_channel} ${flatcar_version} /opt/matchbox.opt/matchbox/assets'

        # WORKAROUND: Needed to support installing VMWare tools
        ExecStartPost=/usr/bin/curl \
          --output-dir /opt/matchbox.opt/matchbox/assets/flatcar/${flatcar_version} \
          -O https://${flatcar_channel}.release.flatcar-linux.net/amd64-usr/${flatcar_version}/flatcar_production_vmware_raw_image.bin.bz2
        ExecStartPost=/usr/bin/curl \
          --output-dir /opt/matchbox.opt/matchbox/assets/flatcar/${flatcar_version} \
          -O https://${flatcar_channel}.release.flatcar-linux.net/amd64-usr/${flatcar_version}/flatcar_production_vmware_raw_image.bin.bz2.sig

        [Install]
        WantedBy=matchbox.service