[pve-devel] [PATCH v5 container 8/9] api: move-volume: add move to another container

[Aaron Lauterer <a.lauterer@proxmox.com>]

The goal of this is to expand the move-volume API endpoint to make it
possible to move a container volume / mountpoint to another container.

For unused volumes, the API parameters have been changed to allow them
as well. This means, additional checks had to be introduced to avoid
migration of an unusedX volume to another storage. Some follow up work
is needed for that to work properly.

Moving the rootfs from or to another container is prohibited.

Signed-off-by: Aaron Lauterer <a.lauterer@proxmox.com>
---
This is mostly the code from qemu-server with some adaptions. Mainly
error messages and some checks.

Previous checks have been moved to '$move_to_storage_checks'.

v4(follow up) -> v5:
* dropped call to PVE::Storage::find_free_volname as it is gone in this
  version
* adapted call to PVE::Storage::rename_volume by now sending the
  target_vmid instead of the target_volame

v4 -> v4(follow up):
In this follow up I introduce the capability to allow moving 'unusedX'
volumes from one container to another.

This includes:
* changing the API parameters to allow for 'unused' config keys with the
  needed method in the LXC/Config.pm to enumerate them.
* added a check to prevent unused volumes to be migrated to other
  storages. Needs some more work to work properly and is on my todo
* the $volume_reassignfn has ssen the most changes as unused volumes
  need to be handled differently than 'mpX' ones when adding them to the
  target CT (writing directly to the config, like done when doing a
  'rescan')

Other changes that happened:
* added checks to prevent the rootfs to/from a container
* removed a double check if the container is running
* rephrased an occurence of 'disk' to 'volume'

v3 -> v4:
* add check to avoid potential undefined warning in $vmlist->{$vmid}
* add check if volume is part of a snapshot
* removed line bloat

v2 -> v3:
* mention default volume key in description
* use $rpcenv->warn should replication snapshot removal fail
    * also print the original error
* code style things

v1 -> v2:
* change --target-mp to --target-volume
* make --target-volume optional and fallback to source mount point
* use parse_volname instead of custom regex
* adapt to find_free_volname
* print warnings from update_pct_config
* move running check back in both lock_config sections
* fixed a few style issues

rfc -> v1:
* add check if target guest is replicated and fail if the moved volume
  does not support it
* check if source volume has a format suffix and pass it to
  'find_free_disk' or if the prefix is vm/subvol as those also have
  their own meaning, see the comment in the code
* fixed some style nits


 src/PVE/API2/LXC.pm | 269 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 247 insertions(+), 22 deletions(-)

diff --git a/src/PVE/API2/LXC.pm b/src/PVE/API2/LXC.pm
index 69df366..8c508bd 100644
--- a/src/PVE/API2/LXC.pm
+++ b/src/PVE/API2/LXC.pm
@@ -1813,10 +1813,12 @@ __PACKAGE__->register_method({
     method => 'POST',
     protected => 1,
     proxyto => 'node',
-    description => "Move a rootfs-/mp-volume to a different storage",
+    description => "Move a rootfs-/mp-volume to a different storage or to a different container.",
     permissions => {
 	description => "You need 'VM.Config.Disk' permissions on /vms/{vmid}, " .
-	    "and 'Datastore.AllocateSpace' permissions on the storage.",
+	    "and 'Datastore.AllocateSpace' permissions on the storage. To move ".
+	    "a volume to another container, you need the permissions on the ".
+	    "target container as well.",
 	check =>
 	[ 'and',
 	  ['perm', '/vms/{vmid}', [ 'VM.Config.Disk' ]],
@@ -1828,14 +1830,20 @@ __PACKAGE__->register_method({
 	properties => {
 	    node => get_standard_option('pve-node'),
 	    vmid => get_standard_option('pve-vmid', { completion => \&PVE::LXC::complete_ctid }),
+	    'target-vmid' => get_standard_option('pve-vmid', {
+		completion => \&PVE::LXC::complete_ctid,
+		optional => 1,
+	    }),
 	    volume => {
 		type => 'string',
-		enum => [ PVE::LXC::Config->valid_volume_keys() ],
+		#TODO: check how to handle unused mount points as the mp parameter is not configured
+		enum => [ PVE::LXC::Config->valid_volume_keys_with_unused() ],
 		description => "Volume which will be moved.",
 	    },
 	    storage => get_standard_option('pve-storage-id', {
 		description => "Target Storage.",
 		completion => \&PVE::Storage::complete_storage_enabled,
+		optional => 1,
 	    }),
 	    delete => {
 		type => 'boolean',
@@ -1856,6 +1864,21 @@ __PACKAGE__->register_method({
 		minimum => '0',
 		default => 'clone limit from datacenter or storage config',
 	    },
+	    'target-volume' => {
+	        type => 'string',
+		description => "The config key the volume will be moved to. Default is the " .
+		    "source volume key.",
+		enum => [PVE::LXC::Config->valid_volume_keys_with_unused()],
+		optional => 1,
+	    },
+	    'target-digest' => {
+		type => 'string',
+		description => 'Prevent changes if current configuration file of the target " .
+		    "container has a different SHA1 digest. This can be used to prevent " .
+		    "concurrent modifications.',
+		maxLength => 40,
+		optional => 1,
+	    },
 	},
     },
     returns => {
@@ -1870,32 +1893,54 @@ __PACKAGE__->register_method({
 
 	my $vmid = extract_param($param, 'vmid');
 
+	my $target_vmid = extract_param($param, 'target-vmid');
+
 	my $storage = extract_param($param, 'storage');
 
 	my $mpkey = extract_param($param, 'volume');
 
+	my $target_mpkey = extract_param($param, 'target-volume') // $mpkey;
+
+	my $digest = extract_param($param, 'digest');
+
+	my $target_digest = extract_param($param, 'target-digest');
+
 	my $lockname = 'disk';
 
 	my ($mpdata, $old_volid);
 
-	PVE::LXC::Config->lock_config($vmid, sub {
-	    my $conf = PVE::LXC::Config->load_config($vmid);
-	    PVE::LXC::Config->check_lock($conf);
+	die "either set storage or target-vmid, but not both\n"
+	    if $storage && $target_vmid;
 
-	    die "cannot move volumes of a running container\n" if PVE::LXC::check_running($vmid);
+	my $storecfg = PVE::Storage::config();
+	my $source_volid;
 
-	    $mpdata = PVE::LXC::Config->parse_volume($mpkey, $conf->{$mpkey});
-	    $old_volid = $mpdata->{volume};
+	my $move_to_storage_checks = sub {
+	    PVE::LXC::Config->lock_config($vmid, sub {
+		my $conf = PVE::LXC::Config->load_config($vmid);
+		PVE::LXC::Config->check_lock($conf);
 
-	    die "you can't move a volume with snapshots and delete the source\n"
-		if $param->{delete} && PVE::LXC::Config->is_volume_in_use_by_snapshots($conf, $old_volid);
+		die "cannot move volumes of a running container\n"
+		    if PVE::LXC::check_running($vmid);
 
-	    PVE::Tools::assert_if_modified($param->{digest}, $conf->{digest});
+		if ($mpkey =~ m/^unused\d+$/) {
+		    die "cannot move volume '$mpkey', only configured volumes can be moved to ".
+			"another storage\n";
+		}
 
-	    PVE::LXC::Config->set_lock($vmid, $lockname);
-	});
+		$mpdata = PVE::LXC::Config->parse_volume($mpkey, $conf->{$mpkey});
+		$old_volid = $mpdata->{volume};
 
-	my $realcmd = sub {
+		die "you can't move a volume with snapshots and delete the source\n"
+		    if $param->{delete} && PVE::LXC::Config->is_volume_in_use_by_snapshots($conf, $old_volid);
+
+		PVE::Tools::assert_if_modified($digest, $conf->{digest});
+
+		PVE::LXC::Config->set_lock($vmid, $lockname);
+	    });
+	};
+
+	my $storage_realcmd = sub {
 	    eval {
 		PVE::Cluster::log_msg('info', $authuser, "move volume CT $vmid: move --volume $mpkey --storage $storage");
 
@@ -1965,15 +2010,195 @@ __PACKAGE__->register_method({
 	    warn $@ if $@;
 	    die $err if $err;
 	};
-	my $task = eval {
-	    $rpcenv->fork_worker('move_volume', $vmid, $authuser, $realcmd);
+
+	my $load_and_check_reassign_configs = sub {
+	    my $vmlist = PVE::Cluster::get_vmlist()->{ids};
+
+	    die "Cannot move to/from 'rootfs'\n" if $mpkey eq "rootfs" || $target_mpkey eq "rootfs";
+
+	    if ($mpkey =~ m/^unused\d+$/ && $target_mpkey !~ m/^unused\d+$/) {
+		die "Moving an unused volume to a used one is not possible\n";
+	    }
+	    die "could not find CT ${vmid}\n" if !exists($vmlist->{$vmid});
+
+	    die "Both containers need to be on the same node ($vmlist->{$vmid}->{node}) ".
+		"but target continer is on $vmlist->{$target_vmid}->{node}.\n"
+		if $vmlist->{$vmid}->{node} ne $vmlist->{$target_vmid}->{node};
+
+	    my $source_conf = PVE::LXC::Config->load_config($vmid);
+	    PVE::LXC::Config->check_lock($source_conf);
+	    my $target_conf = PVE::LXC::Config->load_config($target_vmid);
+	    PVE::LXC::Config->check_lock($target_conf);
+
+	    die "Can't move volumes from or to template VMs\n"
+		if ($source_conf->{template} || $target_conf->{template});
+
+	    if ($digest) {
+		eval { PVE::Tools::assert_if_modified($digest, $source_conf->{digest}) };
+		die "Container ${vmid}: $@" if $@;
+	    }
+
+	    if ($target_digest) {
+		eval { PVE::Tools::assert_if_modified($target_digest, $target_conf->{digest}) };
+		die "Container ${target_vmid}: $@" if $@;
+	    }
+
+	    die "volume '${mpkey}' for container '$vmid' does not exist\n"
+		if !defined($source_conf->{$mpkey});
+
+	    die "Target volume key '${target_mpkey}' is already in use for container '$target_vmid'\n"
+		if exists $target_conf->{$target_mpkey};
+
+	    my $drive = PVE::LXC::Config->parse_volume(
+		$mpkey,
+		$source_conf->{$mpkey},
+	    );
+
+	    $source_volid = $drive->{volume};
+
+	    die "Volume '${mpkey}' has no associated image\n"
+		if !$source_volid;
+	    die "Cannot move volume used by a snapshot to another container\n"
+		if PVE::LXC::Config->is_volume_in_use_by_snapshots($source_conf, $source_volid);
+	    die "Storage does not support moving of this disk to another container\n"
+		if !PVE::Storage::volume_has_feature($storecfg, 'rename', $source_volid);
+	    die "Cannot move a bindmound or device mount to another container\n"
+		if $drive->{type} ne "volume";
+	    die "Cannot move volume to another container while the source container is running\n"
+		if PVE::LXC::check_running($vmid) && $mpkey !~ m/^unused\d+$/;
+
+	    my $repl_conf = PVE::ReplicationConfig->new();
+	    my $is_replicated = $repl_conf->check_for_existing_jobs($target_vmid, 1);
+	    my ($storeid, undef) = PVE::Storage::parse_volume_id($source_volid);
+	    my $format = (PVE::Storage::parse_volname($storecfg, $source_volid))[6];
+	    if (
+		$is_replicated
+		&& !PVE::Storage::storage_can_replicate($storecfg, $storeid, $format)
+	    ) {
+		die "Cannot move volume to a replicated container. Storage " .
+		    "does not support replication!\n";
+	    }
+	    return ($source_conf, $target_conf);
 	};
-	if (my $err = $@) {
-	    eval { PVE::LXC::Config->remove_lock($vmid, $lockname) };
-	    warn $@ if $@;
-	    die $err;
+
+	my $logfunc = sub {
+	    my ($msg) = @_;
+	    print STDERR "$msg\n";
+	};
+
+	my $volume_reassignfn = sub {
+	    return PVE::LXC::Config->lock_config($vmid, sub {
+		return PVE::LXC::Config->lock_config($target_vmid, sub {
+		    my ($source_conf, $target_conf) = &$load_and_check_reassign_configs();
+
+		    my $target_unused = $target_mpkey =~ m/^unused\d+$/;
+
+		    my $drive_param = PVE::LXC::Config->parse_volume(
+			$mpkey,
+			$source_conf->{$mpkey},
+		    );
+
+		    print "moving volume '$mpkey' from container '$vmid' to '$target_vmid'\n";
+		    my ($storage, $source_volname) = PVE::Storage::parse_volume_id($source_volid);
+
+		    my $fmt = (PVE::Storage::parse_volname($storecfg, $source_volid))[6];
+
+		    my $new_volid = PVE::Storage::rename_volume(
+			$storecfg,
+			$source_volid,
+			$target_vmid,
+		    );
+
+		    $drive_param->{volume} = $new_volid;
+
+		    delete $source_conf->{$mpkey};
+		    print "removing volume '${mpkey}' from container '${vmid}' config\n";
+		    PVE::LXC::Config->write_config($vmid, $source_conf);
+
+		    my $drive_string;
+
+		    if ($target_unused) {
+			$drive_string = $new_volid;
+		    } else {
+			$drive_string = PVE::LXC::Config->print_volume($target_mpkey, $drive_param);
+		    }
+
+		    if ($target_unused) {
+			$target_conf->{$target_mpkey} = $drive_string;
+		    } else {
+			my $running = PVE::LXC::check_running($target_vmid);
+			my $param = { $target_mpkey => $drive_string };
+		        my $errors = PVE::LXC::Config->update_pct_config(
+			    $target_vmid,
+			    $target_conf,
+			    $running,
+			    $param
+			);
+
+		        foreach my $key (keys %$errors) {
+		            $rpcenv->warn($errors->{$key});
+		        }
+		    }
+
+		    PVE::LXC::Config->write_config($target_vmid, $target_conf);
+		    $target_conf = PVE::LXC::Config->load_config($target_vmid);
+
+		    PVE::LXC::update_lxc_config($target_vmid, $target_conf) if !$target_unused;
+		    print "target container '$target_vmid' updated with '$target_mpkey'\n";
+
+		    # remove possible replication snapshots
+		    if (PVE::Storage::volume_has_feature($storecfg,'replicate', $source_volid)) {
+			eval {
+			    PVE::Replication::prepare(
+				$storecfg,
+				[$new_volid],
+				undef,
+				1,
+				undef,
+				$logfunc,
+			    )
+			};
+			if (my $err = $@) {
+			    $rpcenv->warn("Failed to remove replication snapshots on volume ".
+				"'${target_mpkey}'. Manual cleanup could be necessary. " .
+				"Error: ${err}\n");
+			}
+		    }
+		});
+	    });
+	};
+
+	if ($target_vmid) {
+	    $rpcenv->check_vm_perm($authuser, $target_vmid, undef, ['VM.Config.Disk'])
+		if $authuser ne 'root@pam';
+
+	    die "Moving a volume to the same container is not possible. Did you ".
+		"mean to move the volume to a different storage?\n"
+		if $vmid eq $target_vmid;
+
+	    &$load_and_check_reassign_configs();
+	    return $rpcenv->fork_worker(
+		'move_volume',
+		"${vmid}-${mpkey}>${target_vmid}-${target_mpkey}",
+		$authuser,
+		$volume_reassignfn
+	    );
+	} elsif ($storage) {
+	    &$move_to_storage_checks();
+	    my $task = eval {
+		$rpcenv->fork_worker('move_volume', $vmid, $authuser, $storage_realcmd);
+	    };
+	    if (my $err = $@) {
+		eval { PVE::LXC::Config->remove_lock($vmid, $lockname) };
+		warn $@ if $@;
+		die $err;
+	    }
+	    return $task;
+	} else {
+	    die "Provide either a 'storage' to move the mount point to a ".
+		"different storage or 'target-vmid' and 'target-mp' to move ".
+		"the mount point to another container\n";
 	}
-	return $task;
   }});
 
 __PACKAGE__->register_method({
-- 
2.30.2