Support for Virt driver

[afbjorklund]

This is a driver based on libvirt.org, for remote hypervisors.

The libvirt functions are in a plugin, to minimize dependencies.

---

Currently only shows version:

var VERSION uint32 = libvirt.VERSION_NUMBER

func Version() (uint32, error) { return libvirt.GetVersion() }

To prove that it can access the API.

[AkihiroSuda]

I think this should be called "libvirt"

[AkihiroSuda]

I also wonder if we can split out this to a separate plugin binary.

Same applies to the vbox driver, cloud drivers, etc.

[afbjorklund]

Sure, it just requires more work. And it would be needed, for cloud.

• Add framework for adding new drivers at runtime, for instance for cloud #2007

[afbjorklund]

Apparently this experiment does not work, since putting libvirt in go.mod requires libvirt-dev:

 No package 'libvirt' found
  Package libvirt was not found in the pkg-config search path.
  Perhaps you should add the directory containing `libvirt.pc'
  to the PKG_CONFIG_PATH environment variable

This makes it impossible to disable, even if it is not used during the build.

So it would need a separate module.

[afbjorklund]

1. Running "session" qemu with libvirt doesn't add any except complexity (until there is proper "system" qemu support)
2. Trying to load libvirt from a plugin doesn't work due to go modules, needs a separate binary like docker-machine-kvm

[afbjorklund]

All that you needed to do was to set the build tag libvirt_dlopen, then it doesn't need pkgconfig or the libraries...
(and that means that there is no real need to use the plugin module, but go straight for RPC for external drivers)

[afbjorklund]

Hmm, libvirt has dozens of connection points (function wrappers) so maybe it should be a plugin after all.
Then Go would still dlopen the virt.so plugin, which would in turn dlopen the libvirt.so.0 library (et al).

[AkihiroSuda]

Would it be possible to just exec virsh?

[afbjorklund]

Yes, that should work. Something like virsh create {{.Dir}}/domain.xml

func CreateDomain(xml string) error {
	conn, err := libvirt.NewConnect(connectString)
	if err != nil {
		return err
	}
	defer conn.Close()
	vm, err := conn.DomainDefineXML(xml)
	if err != nil {
		return err
	}
	return vm.Create()
}

[afbjorklund]

• Support for Virt driver #2054