Improve VM import from external sources

[tomp]

@dinmusic can we learn about the input file format from the initial qemu-img info call (which we would still want to wrap in apparmor etc) and then we can pass the concrete input file format to qemu-img convert?

[tomp]

@dinmusic

API Changes:

The LXD migration API will be extended to support new instance source type conversion and conversionMode. New type is introduced to retain backwards compatibility where instance is created from a raw image format.

Conversion modes allow to choose how the image should be converted during the import phase. Initially, the following options will be supported:

• format (default) - Convert image into a raw format raw format, but virtio drivers are not injected. This works for images that already have virtio drivers present.
• virtio - Inject virtio drivers using virt-v2v-in-place. When enabled, server expects virt-v2v-in-place to be installed on the host.

Please can you expand this section a little. I was expecting to see references to the shared/api structs being modified, with examples of the fields.

[dinmusic]

@tomp

@dinmusic

--conversion=virtio,format

I like that approach. Although ordering shouldn’t matter.

Would the default value for that flag be set to virtio,format?
But would we also support a value of --conversion=none?

I have included the ConversionOptions which are a list of strings that can be passed along the migration request.

I would aim at having format as default value at least at the beginning, since option virtio will require manual installation of virt-v2v-in-place on the host where LXD server is running.

I’ve also updated the spec to include the none conversion option and changes in shared/api.