[pve-devel] [PATCH v2 container] fix: #1075: Correctly restore CT templates form backup

[Christian Ebner]

Restoring a backup from a CT template wrongly resulted in a CT with the template
flag set in the config.
This makes sure the CT template backup gets restored to a CT and only if the
storage supports templates, the resulting CT is converted to a template.
Otherwise the backup restores simply to a CT.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---

Version 2:
    * Minor changes to improve code readability as suggested
    * Refactor check if storage supports templates
    * Omit unneeded call of PVE::LXC::update_lxc_config as the config does not
      exist after a restore anyway

 src/PVE/API2/LXC.pm   | 40 ++++++++++++++++++++++++++++++++--------
 src/PVE/LXC/Create.pm |  4 +++-
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/src/PVE/API2/LXC.pm b/src/PVE/API2/LXC.pm
index 5a8a9c9..cf14d75 100644
--- a/src/PVE/API2/LXC.pm
+++ b/src/PVE/API2/LXC.pm
@@ -335,6 +335,7 @@ __PACKAGE__->register_method({
 
 	my $code = sub {
 	    my $old_conf = PVE::LXC::Config->load_config($vmid);
+	    my $was_template;
 
 	    my $vollist = [];
 	    eval {
@@ -344,6 +345,7 @@ __PACKAGE__->register_method({
 		    if ($is_root && $archive ne '-') {
 			my $orig_conf;
 			($orig_conf, $orig_mp_param) = PVE::LXC::Create::recover_config($archive);
+			$was_template = delete $orig_conf->{template};
 			# When we're root call 'restore_configuration' with ristricted=0,
 			# causing it to restore the raw lxc entries, among which there may be
 			# 'lxc.idmap' entries. We need to make sure that the extracted contents
@@ -423,6 +425,17 @@ __PACKAGE__->register_method({
 		foreach my $mp (keys %$delayed_mp_param) {
 		    $conf->{$mp} = $delayed_mp_param->{$mp};
 		}
+		# If the template flag was set, we try to convert again to template after restore
+		if ($was_template) {
+		    print STDERR "Convert restored container to template...\n";
+		    if (my $err = check_storage_supports_templates($conf)) {
+			warn $err;
+			warn "Leave restored backup as container instead of converting to template.\n"
+		    } else {
+			PVE::LXC::template_create($vmid, $conf);
+			$conf->{template} = 1;
+		    }
+		}
 		PVE::LXC::Config->write_config($vmid, $conf);
 	    };
 	    if (my $err = $@) {
@@ -443,6 +456,22 @@ __PACKAGE__->register_method({
 	return $rpcenv->fork_worker($workername, $vmid, $authuser, $realcmd);
     }});
 
+sub check_storage_supports_templates {
+    my ($conf) = @_;
+
+    my $scfg = PVE::Storage::config();
+    eval {
+	PVE::LXC::Config->foreach_mountpoint($conf, sub {
+	    my ($ms, $mp) = @_;
+
+	    my ($sid) = PVE::Storage::parse_volume_id($mp->{volume}, 0);
+	    die "Warning: Directory storage '$sid' does not support container templates!\n"
+		if $scfg->{ids}->{$sid}->{path};
+	});
+    };
+    return $@
+}
+
 __PACKAGE__->register_method({
     name => 'vmdiridx',
     path => '{vmid}',
@@ -1177,14 +1206,9 @@ __PACKAGE__->register_method({
 	    die "you can't convert a CT to template if the CT is running\n"
 		if PVE::LXC::check_running($vmid);
 
-	    my $scfg = PVE::Storage::config();
-	    PVE::LXC::Config->foreach_mountpoint($conf, sub {
-		my ($ms, $mp) = @_;
-
-		my ($sid) =PVE::Storage::parse_volume_id($mp->{volume}, 0);
-		die "Directory storage '$sid' does not support container templates!\n"
-		    if $scfg->{ids}->{$sid}->{path};
-	    });
+	    if (my $err = check_storage_supports_templates($conf)) {
+		die $err;
+	    }
 
 	    my $realcmd = sub {
 		PVE::LXC::template_create($vmid, $conf);
diff --git a/src/PVE/LXC/Create.pm b/src/PVE/LXC/Create.pm
index c0ef1d7..ed79611 100644
--- a/src/PVE/LXC/Create.pm
+++ b/src/PVE/LXC/Create.pm
@@ -139,7 +139,6 @@ sub recover_config {
 	$conf = PVE::LXC::Config::parse_pct_config("/lxc/0.conf" , $raw);
 
 	delete $conf->{snapshots};
-	delete $conf->{template}; # restored CT is never a template
 
 	PVE::LXC::Config->foreach_mountpoint($conf, sub {
 	    my ($ms, $mountpoint) = @_;
@@ -174,6 +173,9 @@ sub restore_configuration {
 	    next if $key eq 'digest' || $key eq 'rootfs' || $key eq 'snapshots' || $key eq 'unprivileged' || $key eq 'parent';
 	    next if $key =~ /^mp\d+$/; # don't recover mountpoints
 	    next if $key =~ /^unused\d+$/; # don't recover unused disks
+	    # we know if it was a template in the restore API call and check if the target
+	    # storage supports creating a template there
+	    next if $key =~ /^template$/;
 	    if ($restricted && $key eq 'lxc') {
 		warn "skipping custom lxc options, restore manually as root:\n";
 		warn "--------------------------------\n";
-- 
2.11.0