platform: add powervs platform

[Prashanth684]

Add powervs platform support (coreos/fedora-coreos-tracker#817). PowerVS is based on the IBMcloud vpc gen 1 which is similar to openstack.

[Prashanth684]

xref: coreos/coreos-assembler#2200

[Prashanth684]

@lucab could you please take a look and approve? thanks!

[lucab]

I went back reading all the related threads and I wasn't able to find out where/how the userdata configuration is served to a node on this powervs platform. Can you please add an authoritative reference here, or some evidence showing how it works?

Additionally, the openstack provider is notoriously problematic due to its split personality (i.e. network OR disk), so I'd rather not bolt one more thing on top of it.
I have the hope that as a hosted platform, powervs may have a single canonical source (i.e. network XOR disk). Thus, once we answer the question above regarding where the configuration is coming from, I think it may make sense to have a dedicated provider module only implementing the relevant method.

[Prashanth684]

I went back reading all the related threads and I wasn't able to find out where/how the userdata configuration is served to a node on this powervs platform. Can you please add an authoritative reference here, or some evidence showing how it works?

Additionally, the openstack provider is notoriously problematic due to its split personality (i.e. network OR disk), so I'd rather not bolt one more thing on top of it.
I have the hope that as a hosted platform, powervs may have a single canonical source (i.e. network XOR source). Thus, once we answer the question above regarding where the configuration is coming from, I think it may make sense to have a dedicated provider module only implementing the relevant method.

@lucab so as of today the only reference is their API to create a Power VM instance (https://cloud.ibm.com/apidocs/power-cloud#pcloud-pvminstances-post) which makes mention of the user_data and there is no mention of a metadata service. After talking with the IBM folks, confirmed that the metadata service is not supported for PowerVS. They are looking to make this statement explicit and official in their docs.

[lucab]

@Prashanth684 ack, then I guess that once those details have been cleared and written down, this provider can be a simpler "mount config-drive and read this file" logic.

[Prashanth684]

@Prashanth684 ack, then I guess that once those details have been cleared and written down, this provider can be a simpler "mount config-drive and read this file" logic.

ok. IBM has added a statement here - https://cloud.ibm.com/apidocs/power-cloud#pcloud-pvminstances-post that the user_data is fetched from config drive

Cloud-init user-defined data. The user-defined data is made available to the VM instance as a config drive.

I have made the necessary changes to make this provider just mount the config drive and read the file rather than derive from openstack.

[lucab]

For reference, I think I don't have any more remarks on this, I'll happily let @bgilbert drive this through the rest of the journey.

[bgilbert]

Thanks!