fix: a network, pool or secret a VM needs is not stopped or deleted

Stopping a network cut the running VMs on it off, deleting one or a
secret kept the VMs that name it from starting, and stopping a pool
took the disks of running VMs away, all without a word. Each is now
refused with the VMs (and, for a secret, the pools) that need it:
stopping while a running VM uses it, deleting while a VM's definition
names it. A disk given by its file path does not need its pool's
definition. The API's pool stop is refused the same way.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

vrtManager/connection.py

@@ -955,6 +955,17 @@ class wvmConnect(object):
             instances.append(name)
         return instances
 
+    def domains_using(self, match, running_only=False):
+        """Names of the domains with a definition, parsed, that match(tree)
+        holds for: the live and the persistent one of each domain, or with
+        running_only the live one of each running domain."""
+        listing = libvirt.VIR_CONNECT_LIST_DOMAINS_ACTIVE if running_only else 0
+        flags = (0,) if running_only else (0, libvirt.VIR_DOMAIN_XML_INACTIVE)
+        return sorted(
+            dom.name() for dom in self.wvm.listAllDomains(listing)
+            if any(match(etree.fromstring(dom.XMLDesc(f))) for f in flags)
+        )
+
     def paths_in_use(self, skip_uuid=None, own=()):
         """Paths (names for network disks) a domain uses as a disk or a
         backing file of one, or as a file of its snapshots (overlays, memory,

vrtManager/network.py

@@ -161,10 +161,25 @@ class wvmNetwork(wvmConnect):
     def start(self):
         self.net.create()
 
+    def _vms_on_it(self, running_only):
+        name = self.net.name()
+        return self.domains_using(
+            lambda domain: domain.xpath("devices/interface[@type='network']/source[@network=$name]", name=name),
+            running_only,
+        )
+
     def stop(self):
+        """Refused while a running VM is on it: that VM would be cut off."""
+        if vms := self._vms_on_it(running_only=True):
+            raise util.OperationError(f"Network {self.net.name()} is in use by the running VMs {', '.join(vms)}; "
+                                      "shut them down or remove their network cards first")
         self.net.destroy()
 
     def delete(self):
+        """Refused while a VM's definition names it: that VM would no longer start."""
+        if vms := self._vms_on_it(running_only=False):
+            raise util.OperationError(f"VMs {', '.join(vms)} use network {self.net.name()} and would no longer "
+                                      "start; remove their network cards first")
         self.net.undefine()
 
     def update(self, command, section, xml, parentIndex, flags=0):

vrtManager/storage.py

@@ -155,9 +155,27 @@ class wvmStorage(wvmConnect):
         return self.pool.create(0)
 
     def stop(self):
+        """Refused while it holds a disk of a running VM, named by the pool
+        or by a volume's path: that VM would lose the disk."""
+        name = self.pool.name()
+        paths = {vol.path() for vol in self.pool.listAllVolumes()}
+        vms = self.domains_using(
+            lambda domain: domain.xpath("devices/disk/source[@pool=$name]", name=name)
+            or paths.intersection(self._source_paths(domain)),
+            running_only=True,
+        )
+        if vms:
+            raise util.OperationError(f"Pool {name} holds disks of the running VMs {', '.join(vms)}; "
+                                      "shut them down first")
         return self.pool.destroy()
 
     def delete(self):
+        """Refused while a VM's definition names it for a disk: that VM would
+        no longer start. A disk given by its file path does not need it."""
+        name = self.pool.name()
+        if vms := self.domains_using(lambda domain: domain.xpath("devices/disk/source[@pool=$name]", name=name)):
+            raise util.OperationError(f"VMs {', '.join(vms)} have disks in pool {name} by its name and would no "
+                                      "longer start; detach those disks first")
         self.pool.undefine()
 
     def get_autostart(self):

vrtManager/virtsecrets.py

@@ -1,6 +1,7 @@
 import base64
 
 from lxml import etree
+from vrtManager import util
 from vrtManager.connection import wvmConnect
 
 # the element of <usage> that holds the value, per usage type
@@ -22,5 +23,15 @@ class wvmSecrets(wvmConnect):
         secrt.setValue(base64.b64decode(value, validate=True))
 
     def delete_secret(self, uuid):
+        """Refused while a VM disk or a pool names it, by UUID or by usage:
+        without it that VM or pool would no longer start."""
         secrt = self.get_secret(uuid)
+        refs = "//secret[@uuid=$uuid or @usage=$usage]"
+        usage = secrt.usageID() or ""
+        vms = self.domains_using(lambda domain: domain.xpath(f"devices/disk{refs}", uuid=uuid, usage=usage))
+        pools = sorted(pool.name() for pool in self.wvm.listAllStoragePools()
+                       if etree.fromstring(pool.XMLDesc(0)).xpath(f"source{refs}", uuid=uuid, usage=usage))
+        if vms or pools:
+            users = "; ".join(f"{kind} {', '.join(names)}" for kind, names in (("VMs", vms), ("pools", pools)) if names)
+            raise util.OperationError(f"Secret {uuid} is used by {users}; remove it from them first")
         secrt.undefine()