Split `virt` into specialized modules

[mlow]

SUMMARY

Currently virt has rather a lot going on.. it's used both to manage resources (libvirt domains) as well as retrieve information of both individual domains of the libvirt node itself (free memory, etc). I think it would be better to split its functionality into a handful of focused modules. These modules could be added without altering any existing functionality. I would image virt eventually being deprecated.

ISSUE TYPE

• Refactor

COMPONENT NAME

• virt

ADDITIONAL INFORMATION

This is motivated by recent work I've been doing with community.libvirt (working towards a clean, declarative way to deploy libvirt VMs, that isn't Terraform, and finding that community.libvirt needs some work done to get me there :).

One of the needs I've encountered is the ability to retrieve a domain's interface addresses (also seen in #124). I've got a working prototype of this, but it's challenging to figure out the best way to supply the flag controlling the source of the addressing info (arp, lease, or agent). Meanwhile I can envision a way of implementing this in a separate module which focuses on information retrieval, with a signature of something like:

---
- community.libvirt.domain_info:
    name: my-domain
    interface_addresses:
      source: agent

Which would return something like:

{
  "changed": false,
  "interface_addresses": {
     ... raw libvirt data
  }
}

This scheme allows for getting multiple bits of information about a domain at once, e.g.:

---
- community.libvirt.domain_info:
    name: my-domain
    state:
    interface_addresses:
      source: agent

... in a GraphQL-esque fashion, returning data in the same "shape" it's been requested in:

{
  "changed": false,
  "state": "running",
  "interface_addresses": {
     ... raw libvirt data
  }
}

The other modules I would expect are:

• domain - focusing on domain management (idempotent XML definition and state (running, stopped) management)
• node_info - for retrieval of node-wide information (free mem, etc)

I would love for any feedback on the above proposals. If there's agreement that they seem worthwhile, I'll be happy to get started on them.

Cheers