feat(instances): grow a disk while the VM runs or is paused

The resize tab enabled disk growth only for a shut-off VM, although
resize_disk already grows a running domain's disk through blockResize.
The button is now enabled for running and paused VMs too. A live test
grows qcow2 and raw disks of a running and of a paused VM and checks the
size the guest sees, the volume size, the unchanged persistent definition
and the state.

instances/test_live_disk_resize.py

@@ -0,0 +1,86 @@
+"""Live checks that a disk grows while its VM runs or is paused.
+
+QEMU holds a running domain's image, so the size goes through blockResize;
+the guest and the volume must both see it, and the persistent definition
+stays as it was. Runs only with TEST_LIBVIRT_HOST set (see instances/livetest.py).
+"""
+
+import os
+import unittest
+
+import libvirt
+from django.test import SimpleTestCase
+from vrtManager.connection import connection_manager
+from vrtManager.instance import wvmInstance
+
+from . import livetest
+
+P = livetest.PREFIX
+PERSISTENT = libvirt.VIR_DOMAIN_XML_INACTIVE | libvirt.VIR_DOMAIN_XML_SECURE
+
+
+class LiveDiskResizeTestCase(SimpleTestCase):
+    @classmethod
+    def setUpClass(cls):
+        if not livetest.enabled():
+            raise unittest.SkipTest("Set TEST_LIBVIRT_HOST to run the live libvirt tests")
+        cls.args = (
+            os.environ["TEST_LIBVIRT_HOST"],
+            os.environ.get("TEST_LIBVIRT_LOGIN", ""),
+            os.environ.get("TEST_LIBVIRT_PASSWORD", ""),
+            int(os.environ.get("TEST_LIBVIRT_TYPE", 4)),
+        )
+        cls.conn = connection_manager.get_connection(*cls.args)
+        livetest.cleanup(cls.conn)
+        livetest.ensure_pool(cls.conn)
+        cls.inventory = livetest.inventory(cls.conn)
+        super().setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        try:
+            livetest.remove_pool(cls.conn)
+        finally:
+            super().tearDownClass()
+        if livetest.inventory(cls.conn) != cls.inventory:
+            raise AssertionError("Live tests changed objects outside the test namespace")
+
+    def tearDown(self):
+        livetest.cleanup(self.conn)
+
+    def vm(self, name, fmt):
+        pool = self.conn.storagePoolLookupByName(livetest.POOL)
+        vol = pool.createXML(
+            f"<volume><name>{P}{name}.{fmt}</name><capacity unit='MiB'>64</capacity>"
+            f"<target><format type='{fmt}'/></target></volume>",
+            0,
+        )
+        dom = self.conn.defineXML(
+            f"<domain type='kvm'><name>{P}{name}</name><memory unit='MiB'>128</memory><vcpu>1</vcpu>"
+            "<os><type arch='x86_64' machine='q35'>hvm</type></os><features><acpi/></features><devices>"
+            f"<disk type='file' device='disk'><driver name='qemu' type='{fmt}'/>"
+            f"<source file='{vol.path()}'/><target dev='vda' bus='virtio'/></disk></devices></domain>"
+        )
+        return dom, vol, wvmInstance(*self.args, f"{P}{name}")
+
+    def test_a_disk_grows_while_the_vm_runs_or_is_paused(self):
+        new_size = 96 << 20
+        for state in ("running", "paused"):
+            for fmt in ("qcow2", "raw"):
+                with self.subTest(state=state, fmt=fmt):
+                    try:
+                        dom, vol, vm = self.vm(f"resize-{state}-{fmt}", fmt)
+                        dom.create()
+                        if state == "paused":
+                            dom.suspend()
+                        before = dom.XMLDesc(PERSISTENT)
+
+                        disk = vm.get_disk_devices()[0]
+                        vm.resize_disk([{"path": disk["path"], "size_new": new_size}])
+
+                        self.assertEqual(dom.blockInfo(disk["path"])[0], new_size, "the guest's disk")
+                        self.assertEqual(vol.info()[1], new_size, "the volume")
+                        self.assertEqual(dom.XMLDesc(PERSISTENT), before)
+                        self.assertEqual(dom.state()[0], libvirt.VIR_DOMAIN_PAUSED if state == "paused" else libvirt.VIR_DOMAIN_RUNNING)
+                    finally:
+                        livetest.cleanup(self.conn)