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

[Thomas Lamprecht]

On 4/16/19 5:37 PM, Christian Ebner wrote:
> 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.

a not-tested-just-looked-at review below ;-)

> 
> Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
> ---
>  src/PVE/API2/LXC.pm   | 28 ++++++++++++++++++++++++++++
>  src/PVE/LXC/Create.pm |  2 +-
>  2 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/src/PVE/API2/LXC.pm b/src/PVE/API2/LXC.pm
> index 5a8a9c9..42e11fb 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 $vollist = [];
>  	    eval {
> @@ -344,6 +345,10 @@ __PACKAGE__->register_method({
>  		    if ($is_root && $archive ne '-') {
>  			my $orig_conf;
>  			($orig_conf, $orig_mp_param) = PVE::LXC::Create::recover_config($archive);
> +			if ($orig_conf->{template}) {
> +			    $was_template = $orig_conf->{template};
> +			    delete $orig_conf->{template};
> +			}

whole block can be reduced to a single line, like:
$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
> @@ -424,6 +429,29 @@ __PACKAGE__->register_method({
>  		    $conf->{$mp} = $delayed_mp_param->{$mp};
>  		}
>  		PVE::LXC::Config->write_config($vmid, $conf);
> +
> +		# If the template flag was set, we try to convert again to template after restore
> +		if ($was_template) {
> +		    print STDERR "Convert restored container to template...\n";

from here -
> +		    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!\nLeave restored backup as container instead\n"
> +				if $scfg->{ids}->{$sid}->{path};
> +			});
> +		    };

do here it's a straight copy from the POST template call below, we could
either factor this out in a method which gets only the conf (scfg can be
obtained inside) or a module wide closure, as both calls are located here,
not sure what feels better, but I'd like to not have this twice here.

> +		    if (my $err = $@) {
> +			warn $err;
> +		    } else {

hmm this is also a straight copy from the template create API call..

> +			PVE::LXC::template_create($vmid, $conf);
> +			$conf->{template} = 1;
> +			PVE::LXC::Config->write_config($vmid, $conf);

this write could be removed if we move this all a bit up, as there a write is
already in place

> +			PVE::LXC::update_lxc_config($vmid, $conf);

a comment for above could be nice, for templates it just removes the
local generated LXC config and early returns.


> +		    }
> +		}
>  	    };
>  	    if (my $err = $@) {
>  		PVE::LXC::destroy_disks($storage_cfg, $vollist);
> diff --git a/src/PVE/LXC/Create.pm b/src/PVE/LXC/Create.pm
> index c0ef1d7..4b527ff 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 +173,7 @@ 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
> +	    next if $key =~ /^template$/; # restored CT is never a template by default

maybe a comment more like:

# we know if it was a template in the restore API call and check if the target
# storage supports creating a template there

>  	    if ($restricted && $key eq 'lxc') {
>  		warn "skipping custom lxc options, restore manually as root:\n";
>  		warn "--------------------------------\n";
>