boot volume: use size of backing volume

So far this was hard coded to 10G, which for example did not allow to
boot bigger images like - haha - "Micro"OS.

Author: rck

internal/virter/libvirt_test.go

@@ -160,6 +160,15 @@ func (l *FakeLibvirtConnection) StorageVolDownload(Vol libvirt.StorageVol, inStr
 	return nil
 }
 
+func (l *FakeLibvirtConnection) StorageVolGetInfo(Vol libvirt.StorageVol) (rType int8, rCapacity uint64, rAllocation uint64, err error) {
+	_, ok := l.vols[Vol.Name]
+	if !ok {
+		return 0, 0, 0, mockLibvirtError(errNoStorageVol)
+	}
+
+	return 0, 42, 23, nil
+}
+
 func (l *FakeLibvirtConnection) NetworkLookupByName(Name string) (rNet libvirt.Network, err error) {
 	if Name != networkName {
 		return libvirt.Network{}, errors.New("unknown network")

internal/virter/libvirtxml.go

@@ -197,8 +197,8 @@ func (v *Virter) ciDataVolumeXML(name string) (string, error) {
 	return v.diskVolumeXML(name, 0, "B", "raw")
 }
 
-func (v *Virter) vmVolumeXML(name string, backingPath string) (string, error) {
-	volume := v.diskVolume(name, 10, "GiB", "qcow2")
+func (v *Virter) vmVolumeXML(name string, backingPath string, sizeB uint64) (string, error) {
+	volume := v.diskVolume(name, sizeB, "B", "qcow2")
 	volume.BackingStore = &lx.StorageVolumeBackingStore{
 		Path:   backingPath,
 		Format: &lx.StorageVolumeTargetFormat{Type: "qcow2"},

internal/virter/virter.go

@@ -24,6 +24,7 @@ type LibvirtConnection interface {
 	StorageVolGetXMLDesc(Vol libvirt.StorageVol, Flags uint32) (rXML string, err error)
 	StorageVolCreateXMLFrom(Pool libvirt.StoragePool, XML string, Clonevol libvirt.StorageVol, Flags libvirt.StorageVolCreateFlags) (rVol libvirt.StorageVol, err error)
 	StorageVolDownload(Vol libvirt.StorageVol, inStream io.Writer, Offset uint64, Length uint64, Flags libvirt.StorageVolDownloadFlags) (err error)
+	StorageVolGetInfo(Vol libvirt.StorageVol) (rType int8, rCapacity uint64, rAllocation uint64, err error)
 	NetworkLookupByName(Name string) (rNet libvirt.Network, err error)
 	NetworkGetXMLDesc(Net libvirt.Network, Flags uint32) (rXML string, err error)
 	NetworkUpdate(Net libvirt.Network, Command uint32, Section uint32, ParentIndex int32, XML string, Flags libvirt.NetworkUpdateFlags) (err error)

internal/virter/vm.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/LINBIT/virter/pkg/netcopy"
+	"github.com/rck/unit"
 
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/crypto/ssh"
@@ -142,7 +143,16 @@ func (v *Virter) createVMVolume(sp libvirt.StoragePool, vmConfig VMConfig) error
 		return fmt.Errorf("could not get backing image path: %w", err)
 	}
 
-	xml, err := v.vmVolumeXML(vmName, backingPath)
+	_, sizeB, _, err := v.libvirt.StorageVolGetInfo(backingVolume)
+	if err != nil {
+		return fmt.Errorf("could not get backing image info: %w", err)
+	}
+	minSize := uint64(10 * unit.G)
+	if sizeB < minSize {
+		sizeB = minSize
+	}
+
+	xml, err := v.vmVolumeXML(vmName, backingPath, sizeB)
 	if err != nil {
 		return err
 	}