[PATCH pve-container v5 5/7] api: record CT ID as used on creation, cloning, and destruction

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

Record an ID as used when a container 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 CT 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/LXC.pm | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/PVE/API2/LXC.pm b/src/PVE/API2/LXC.pm
index 5f94d5a1..73c06fbd 100644
--- a/src/PVE/API2/LXC.pm
+++ b/src/PVE/API2/LXC.pm
@@ -26,6 +26,7 @@ use PVE::SafeSyslog;
 use PVE::Storage;
 use PVE::Ticket;
 use PVE::Tools qw(extract_param run_command);
+use PVE::UsedGuestIDs;
 use PVE::VZDump::Plugin;
 
 use PVE::LXC;
@@ -422,6 +423,10 @@ __PACKAGE__->register_method({
 
         my $emsg = $restore ? "unable to restore CT $vmid -" : "unable to create CT $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 $@;
+
         eval { PVE::LXC::Config->create_and_lock_config($vmid, $force) };
         die "$emsg $@" if $@;
 
@@ -882,6 +887,10 @@ __PACKAGE__->register_method({
 
         $early_checks->($conf);
 
+        # record before destroying anything, so a failure here leaves the CT intact
+        eval { PVE::UsedGuestIDs::add_id($vmid) };
+        die "unable to destroy CT $vmid - could not record VMID as used - $@" if $@;
+
         my $running_error_msg = "unable to destroy CT $vmid - container is running\n";
         die $running_error_msg if !$param->{force} && PVE::LXC::check_running($vmid); # check early
 
@@ -2038,6 +2047,10 @@ __PACKAGE__->register_method({
             );
         };
 
+        # record before the config exists, so a failure here leaves nothing behind
+        eval { PVE::UsedGuestIDs::add_id($newid) };
+        die "unable to clone CT $vmid - could not record VMID $newid as used - $@" if $@;
+
         my $src_conf = PVE::LXC::Config->set_lock($vmid, 'disk');
 
         eval { PVE::LXC::Config->create_and_lock_config($newid, 0); };
@@ -3148,6 +3161,11 @@ __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 CT $vmid - could not record VMID as used - $@" if $@;
+
         my $socket_addr = "/run/pve/ct-$vmid.mtunnel";
 
         my $lock = 'create';
-- 
2.47.3