[PATCH qemu-server v5 4/7] api: record VM ID as used on creation, cloning, and destruction

["Michael Köppl" <m.koeppl@proxmox.com>]

Record an ID as used when a VM is created, cloned, destroyed, or brought
in by a remote migration, so that the `/cluster/nextid` endpoint can
later optionally avoid suggesting previously used IDs.

Recording is done on creation as well such that the ID stays recorded
even when a user removes the config by hand, which bypasses the destroy
API.

Each call happens before the first persistent change and a failure to
record aborts the operation. That way a VM is never created or destroyed
without its ID being recorded and a failure leaves nothing half-done
behind.

Originally-by: Daniel Krambrock <krambrock@hrz.uni-marburg.de>
Originally-by: Severen Redwood <severen.redwood@sitehost.co.nz>
Signed-off-by: Michael Köppl <m.koeppl@proxmox.com>
---
 src/PVE/API2/Qemu.pm | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/PVE/API2/Qemu.pm b/src/PVE/API2/Qemu.pm
index 71247eec..c2571f0c 100644
--- a/src/PVE/API2/Qemu.pm
+++ b/src/PVE/API2/Qemu.pm
@@ -68,6 +68,7 @@ use PVE::ReplicationState;
 use PVE::StorageTunnel;
 use PVE::RESTEnvironment qw(log_warn);
 use PVE::Ticket;
+use PVE::UsedGuestIDs;
 
 BEGIN {
     if (!$ENV{PVE_GENERATING_DOCS}) {
@@ -1371,6 +1372,10 @@ __PACKAGE__->register_method({
 
         my $emsg = $is_restore ? "unable to restore VM $vmid -" : "unable to create VM $vmid -";
 
+        # record before the config exists, so a failure here leaves nothing behind
+        eval { PVE::UsedGuestIDs::add_id($vmid) };
+        die "$emsg could not record VMID as used - $@" if $@;
+
         eval { PVE::QemuConfig->create_and_lock_config($vmid, $force) };
         die "$emsg $@" if $@;
 
@@ -2847,6 +2852,10 @@ __PACKAGE__->register_method({
 
         $early_checks->();
 
+        # record before destroying anything, so a failure here leaves the VM intact
+        eval { PVE::UsedGuestIDs::add_id($vmid) };
+        die "unable to destroy VM $vmid - could not record VMID as used - $@" if $@;
+
         my $realcmd = sub {
             my $upid = shift;
 
@@ -4610,6 +4619,10 @@ __PACKAGE__->register_method({
                 $newconf->{description} = $param->{description};
             }
 
+            # record before the config exists, so a failure here leaves nothing behind
+            eval { PVE::UsedGuestIDs::add_id($newid) };
+            die "unable to clone VM $vmid - could not record VMID $newid as used - $@" if $@;
+
             # create empty/temp config - this fails if VM already exists on other node
             # FIXME use PVE::QemuConfig->create_and_lock_config and adapt code
             PVE::Tools::file_set_contents($conffile, "# qmclone temporary file\nlock: clone\n");
@@ -6708,6 +6721,11 @@ __PACKAGE__->register_method({
 
         PVE::Cluster::check_cfs_quorum();
 
+        # remote migration brings in a VMID this cluster has not seen,
+        # so record it here
+        eval { PVE::UsedGuestIDs::add_id($vmid) };
+        die "unable to create VM $vmid - could not record VMID as used - $@" if $@;
+
         my $lock = 'create';
         eval { PVE::QemuConfig->create_and_lock_config($vmid, 0, $lock); };
 
-- 
2.47.3