[pve-devel] [PATCH v5 qemu-server 2/5] disk reassign: add API endpoint
Fabian Grünbichler
f.gruenbichler at proxmox.com
Wed Mar 31 11:23:08 CEST 2021
sorry for the long pause - haven't checked the GUI part, but that should
be unaffected by my comments in-line.
On December 15, 2020 1:48 pm, Aaron Lauterer wrote:
> The goal of this new API endpoint is to provide an easy way to move a
> disk between VMs as this was only possible with manual intervention
> until now. Either by renaming the VM disk or by manually adding the
> disks volid to the config of the other VM.
>
> The latter can easily cause unexpected behavior such as disks attached
> to VM B would be deleted if it used to be a disk of VM A. This happens
> because PVE assumes that the VMID in the volname always matches the VM
> the disk is attached to and thus, would remove any disk with VMID A
> when VM A was deleted.
>
> The term `reassign` was chosen as it is not yet used
> for VM disks.
>
> Signed-off-by: Aaron Lauterer <a.lauterer at proxmox.com>
> ---
> v4 -> v5:
> * implemented suggestions from Fabian [1]
> * logging before action
> * improving description
> * improving error messages
> * using Replication::prepare to remove replication snapshots
> * check if disk is physical disk using /dev/...
>
> v3 -> v4: nothing
>
> v2 -> v3:
> * reordered the locking as discussed with fabian [0] to
> run checks
> fork worker
> lock source config
> lock target config
> run checks
> ...
>
> * added more checks
> * will not reassign to or from templates
> * will not reassign if VM has snapshots present
> * cleanup if disk used to be replicated
> * made task log slightly more verbose
> * integrated general recommendations regarding code
> * renamed `disk` to `drive_key`
> * prepended some vars with `source_` for easier distinction
>
> v1 -> v2: print config key and volid info at the end of the job so it
> shows up on the CLI and task log
>
> rfc -> v1:
> * add support to reassign unused disks
> * add support to provide a config digest for the target vm
> * add additional check if disk key is present in config
> * reorder checks a bit
>
> In order to support unused disk I had to extend
> PVE::QemuServer::Drive::valid_drive_names for the API parameter
> validation.
>
> Checks are ordered so that cheap tests are run at the first chance to
> fail early.
>
> The check if both VMs are present on the node is a bit redundant because
> locking the config files will fail if the VM is not present. But with
> the additional check we can provide a useful error message to the user
> instead of a "Configuration file xyz does not exist" error.
>
> [0] https://lists.proxmox.com/pipermail/pve-devel/2020-September/044930.html
> [1] https://lists.proxmox.com/pipermail/pve-devel/2020-November/046030.html
>
> PVE/API2/Qemu.pm | 151 ++++++++++++++++++++++++++++++++++++++++
> PVE/QemuServer/Drive.pm | 4 ++
> 2 files changed, 155 insertions(+)
>
> diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
> index 00d98ab..614f068 100644
> --- a/PVE/API2/Qemu.pm
> +++ b/PVE/API2/Qemu.pm
> @@ -35,6 +35,7 @@ use PVE::API2::Qemu::Agent;
> use PVE::VZDump::Plugin;
> use PVE::DataCenterConfig;
> use PVE::SSHInfo;
> +use PVE::Replication;
>
> BEGIN {
> if (!$ENV{PVE_GENERATING_DOCS}) {
> @@ -4319,4 +4320,154 @@ __PACKAGE__->register_method({
> return PVE::QemuServer::Cloudinit::dump_cloudinit_config($conf, $param->{vmid}, $param->{type});
> }});
>
> +__PACKAGE__->register_method({
> + name => 'reassign_vm_disk',
> + path => '{vmid}/reassign_disk',
> + method => 'POST',
> + protected => 1,
> + proxyto => 'node',
> + description => "Reassign a disk to another VM",
> + permissions => {
> + description => "You need 'VM.Config.Disk' permissions on /vms/{vmid} and /vms/{target vmid}, and 'Datastore.Allocate' permissions on the storage.",
> + check => [ 'and',
> + ['perm', '/vms/{vmid}', [ 'VM.Config.Disk' ]],
> + ['perm', '/storage/{storage}', [ 'Datastore.Allocate' ]],
> + ],
did you actually check this works? you can check the source vmid here,
but the rest as described in the schema needs to be manually checked
down below..
> + },
> + parameters => {
> + additionalProperties => 0,
> + properties => {
> + node => get_standard_option('pve-node'),
> + vmid => get_standard_option('pve-vmid', { completion => \&PVE::QemuServer::complete_vmid }),
> + target_vmid => get_standard_option('pve-vmid', { completion => \&PVE::QemuServer::complete_vmid }),
> + drive_name => {
> + type => 'string',
> + description => "The config key of the disk to reassign (for example, ide0 or scsi1).",
> + enum => [PVE::QemuServer::Drive::valid_drive_names_with_unused()],
> + },
> + digest => {
> + type => 'string',
> + description => 'Prevent changes if current the configuration file of the source VM has a different SHA1 digest. This can be used to prevent concurrent modifications.',
> + maxLength => 40,
> + optional => 1,
> + },
> + target_digest => {
> + type => 'string',
> + description => 'Prevent changes if current the configuration file of the target VM has a different SHA1 digest. This can be used to prevent concurrent modifications.',
> + maxLength => 40,
> + optional => 1,
> + },
> + },
> + },
> + returns => {
> + type => 'string',
> + description => "the task ID.",
> + },
> + code => sub {
> + my ($param) = @_;
> +
> + my $rpcenv = PVE::RPCEnvironment::get();
> + my $authuser = $rpcenv->get_user();
> +
> + my $node = extract_param($param, 'node');
> + my $source_vmid = extract_param($param, 'vmid');
> + my $target_vmid = extract_param($param, 'target_vmid');
> + my $source_digest = extract_param($param, 'digest');
> + my $target_digest = extract_param($param, 'target_digest');
> + my $drive_name = extract_param($param, 'drive_name');
> +
> + my $storecfg = PVE::Storage::config();
> + my $vmlist;
> + my $drive;
> + my $source_volid;
> +
> + die "Reassigning a disk to the same VM is not possible. Did you mean to move the disk?\n"
> + if $source_vmid eq $target_vmid;
> +
> + my $load_and_check_configs = sub {
> + $vmlist = PVE::Cluster::get_vmlist()->{ids};
> + die "Both VMs need to be on the same node ($vmlist->{$source_vmid}->{node}) but target VM is on $vmlist->{$target_vmid}->{node}.\n"
> + if $vmlist->{$source_vmid}->{node} ne $vmlist->{$target_vmid}->{node};
> +
> + my $source_conf = PVE::QemuConfig->load_config($source_vmid);
> + PVE::QemuConfig->check_lock($source_conf);
> + my $target_conf = PVE::QemuConfig->load_config($target_vmid);
> + PVE::QemuConfig->check_lock($target_conf);
> +
> + die "Can't reassign disks from or to templates\n"
> + if ($source_conf->{template} || $target_conf->{template});
> +
> + if ($source_digest) {
> + eval { PVE::Tools::assert_if_modified($source_digest, $source_conf->{digest}) };
> + if (my $err = $@) {
> + die "VM ${source_vmid}: ${err}";
> + }
> + }
> +
> + if ($target_digest) {
> + eval { PVE::Tools::assert_if_modified($target_digest, $target_conf->{digest}) };
> + if (my $err = $@) {
> + die "VM ${target_vmid}: ${err}";
> + }
> + }
> +
> + die "Disk '${drive_name}' does not exist\n"
> + if !defined($source_conf->{$drive_name});
> +
> + $drive = PVE::QemuServer::parse_drive($drive_name, $source_conf->{$drive_name});
> + $source_volid = $drive->{file};
> + die "disk '${drive_name}' has no associated volume\n" if !$source_volid;
> + die "CD drive contents can't be reassigned\n" if PVE::QemuServer::drive_is_cdrom($drive, 1);
> + die "Can't reassign physical disk\n" if $drive->{file} =~ m|^/dev/|;
> + die "Can't reassign disk used by a snapshot\n"
> + if PVE::QemuServer::Drive::is_volume_in_use($storecfg, $source_conf, $drive_name, $source_volid);
> +
> + die "Storage does not support the reassignment of this disk\n"
> + if !PVE::Storage::volume_has_feature($storecfg, 'reassign', $source_volid);
> +
> + die "Cannot reassign disk while the source VM is running\n"
> + if PVE::QemuServer::check_running($source_vmid) && $drive_name !~ m/unused[0-9]/;
we use /^unused\d+$/ in other places for this, which is a bit less
error-prone in case we ever add other "unused" keys..
> +
> + return ($source_conf, $target_conf);
> + };
> +
> + my $logfunc = sub {
> + my ($msg) = @_;
> + print STDERR "$msg\n";
> + };
> +
> + my $reassign_func = sub {
> + return PVE::QemuConfig->lock_config($source_vmid, sub {
> + return PVE::QemuConfig->lock_config($target_vmid, sub {
> + my ($source_conf, $target_conf) = &$load_and_check_configs();
> +
> + PVE::Cluster::log_msg('info', $authuser, "reassign disk VM $source_vmid: reassign --disk ${drive_name} --target_vmid $target_vmid");
> +
> + my $new_volid = PVE::Storage::reassign_volume($storecfg, $source_volid, $target_vmid);
> +
> + delete $source_conf->{$drive_name};
> + print "removing disk '${drive_name}' from VM '${source_vmid}'\n";
> + PVE::QemuConfig->write_config($source_vmid, $source_conf);
> +
> + # remove possible replication snapshots
> + PVE::Replication::prepare($storecfg, [$new_volid], undef, undef, undef, $logfunc);
might make sense to wrap this in an eval as well, and print an
appropriate warning that manual cleanup might be required here as well..
> +
> + my $key;
> + eval { $key = PVE::QemuConfig->add_unused_volume($target_conf, $new_volid) };
> + if (my $err = $@) {
> + print "failed to add reassigned disk '${new_volid}' to VM '${target_vmid}'. Try to free an 'unused' disk slot and run 'qm rescan ${target_vmid}'.\n";
> + return 0;
> + }
> +
> + print "adding disk to VM '${target_vmid}' as '${key}: ${new_volid}'\n";
> + PVE::QemuConfig->write_config($target_vmid, $target_conf);
> + });
> + });
> + };
> +
> + &$load_and_check_configs();
> +
> + return $rpcenv->fork_worker('qmreassign', $source_vmid, $authuser, $reassign_func);
> + }});
> +
> 1;
> diff --git a/PVE/QemuServer/Drive.pm b/PVE/QemuServer/Drive.pm
> index d560937..95c0538 100644
> --- a/PVE/QemuServer/Drive.pm
> +++ b/PVE/QemuServer/Drive.pm
> @@ -383,6 +383,10 @@ sub valid_drive_names {
> 'efidisk0');
> }
>
> +sub valid_drive_names_with_unused {
> + return (valid_drive_names(), map {"unused$_"} (0 .. ($MAX_UNUSED_DISKS -1)));
> +}
> +
> sub is_valid_drivename {
> my $dev = shift;
>
> --
> 2.20.1
>
>
>
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