virt-install: Default to qcow2 for new images

Following along with virt-manager's change. It has all the features and
good enough performace, and is easy enough to override for people that
care.

man/virt-install.pod

@@ -565,6 +565,8 @@ read and write caching.
 
 Disk image format. For file volumes, this can be 'raw', 'qcow2', 'vmdk', etc. See format types in L<http://libvirt.org/storage.html> for possible values. This is often mapped to the B<driver_type> value as well.
 
+If not specified when creating file images, this will default to 'qcow2'.
+
 If creating storage, this will be the format of the new image. If using an existing image, this overrides libvirt's format auto-detection.
 
 =item B<driver_name>
@@ -1417,17 +1419,17 @@ C<~/.cache/virt-manager/virt-install.log> even if this parameter is omitted.
 
 =head1 EXAMPLES
 
-Install a Fedora 13 KVM guest with virtio accelerated disk/network,
-creating a new 8GB storage file, installing from media in the hosts
-CDROM drive, auto launching a graphical VNC viewer
+Install a Fedora 20 KVM guest with virtio accelerated disk/network,
+creating a new 10GB qcow2 file, installing from media in the hosts
+CDROM drive. This will use Spice graphics by default, and launch autolaunch
+a graphical client.
 
   # virt-install \
        --connect qemu:///system \
        --virt-type kvm \
        --name demo \
        --memory 500 \
-       --disk size=8 \
-       --graphics vnc \
+       --disk size=10 \
        --cdrom /dev/cdrom \
        --os-variant fedora13
 

tests/cli-test-xml/compare/virt-install-many-devices.xml

@@ -69,6 +69,10 @@
       </iotune>
       <readonly/>
     </disk>
+    <disk type="file" device="disk">
+      <source file="/var/lib/libvirt/images/foobar.qcow2"/>
+      <target dev="hdc" bus="ide"/>
+    </disk>
     <controller type="usb" index="0" model="ich9-ehci1">
       <address type="pci" domain="0" bus="0" slot="4" function="7"/>
     </controller>
@@ -209,6 +213,10 @@
       </iotune>
       <readonly/>
     </disk>
+    <disk type="file" device="disk">
+      <source file="/var/lib/libvirt/images/foobar.qcow2"/>
+      <target dev="hdc" bus="ide"/>
+    </disk>
     <controller type="usb" index="0" model="ich9-ehci1">
       <address type="pci" domain="0" bus="0" slot="4" function="7"/>
     </controller>

tests/clitest.py

@@ -548,6 +548,7 @@ c.add_compare("""--hvm --pxe \
 --disk %(EXISTUPPER)s,cache=writeback,io=threads,perms=sh,serial=WD-WMAP9A966149,boot_order=2 \
 --disk %(NEWIMG1)s,sparse=false,size=.001,perms=ro,error_policy=enospace \
 --disk device=cdrom,bus=sata,read_bytes_sec=1,read_iops_sec=2,total_bytes_sec=10,total_iops_sec=20,write_bytes_sec=5,write_iops_sec=6 \
+--disk size=1 \
 --serial tcp,host=:2222,mode=bind,protocol=telnet \
 --filesystem /source,/target,mode=squash \
 --network user,mac=12:34:56:78:11:22 \

virtManager/connection.py

@@ -360,12 +360,13 @@ class vmmConnection(vmmGObject):
 
         fmt = self.config.get_default_storage_format()
         if fmt != "qcow2":
-            return
+            return fmt
 
         if self.check_support(self._backend.SUPPORT_CONN_DEFAULT_QCOW2):
             return fmt
         return None
 
+
     ####################################
     # Connection pretty print routines #
     ####################################

virtinst/cli.py

@@ -1522,6 +1522,12 @@ class ParserPM(VirtCLIParser):
 # --disk parsing #
 ##################
 
+def _default_image_file_format(conn):
+    if conn.check_support(conn.SUPPORT_CONN_DEFAULT_QCOW2):
+        return "qcow2"
+    return "raw"
+
+
 def _parse_disk_source(guest, path, pool, vol, size, fmt, sparse):
     abspath = None
     volinst = None
@@ -1556,7 +1562,7 @@ def _parse_disk_source(guest, path, pool, vol, size, fmt, sparse):
         tmpvol = virtinst.StorageVolume(guest.conn)
         tmpvol.pool = poolobj
         if fmt is None and tmpvol.file_type == tmpvol.TYPE_FILE:
-            fmt = "raw"
+            fmt = _default_image_file_format(guest.conn)
 
         ext = virtinst.StorageVolume.get_file_extension_for_format(fmt)
         vname = virtinst.StorageVolume.find_free_name(