[pve-devel] [PATCH qemu-server 2/3] config: introduce a flag to prevent writing the configuration

[Thomas Lamprecht]

Am 24.01.25 um 11:08 schrieb Fiona Ebner:
> To be used in the context of template backup, where a minimized
> temporary configuration is created to start the VM in 'prelaunch'
> mode. Issue a warning, so that code paths where this happens will be
> noted and can be evaluated and adapted.
> 
> Suggested-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
> Signed-off-by: Fiona Ebner <f.ebner at proxmox.com>
> ---
>  PVE/QemuConfig.pm | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/PVE/QemuConfig.pm b/PVE/QemuConfig.pm
> index ffdf9f03..a2156abb 100644
> --- a/PVE/QemuConfig.pm
> +++ b/PVE/QemuConfig.pm
> @@ -13,6 +13,7 @@ use PVE::QemuServer::Monitor qw(mon_cmd);
>  use PVE::QemuServer;
>  use PVE::QemuServer::Machine;
>  use PVE::QemuServer::Memory qw(get_current_memory);
> +use PVE::RESTEnvironment qw(log_warn);
>  use PVE::Storage;
>  use PVE::Tools;
>  use PVE::Format qw(render_bytes render_duration);
> @@ -561,6 +562,17 @@ sub get_derived_property {
>      }
>  }
>  
> +sub write_config {
> +    my ($class, $vmid, $conf) = @_;
> +
> +    if ($conf->{'no-write-config'}) {
> +	log_warn("refusing to write temporary configuration with 'no-write-config' flag");

hmm, mixing config values and metadata for control flow/debugging is
always getting hairy fast, making the config a blessed object with
method for QEMU stuff and a clean separation of config data and such
flags and other non-config data info might be a better alternative,
but demanding that now would add a ton of scope and delay the fix
significantly, so fine to go this way as stop gap.

On a v2 or on applying adding a (one of) fixme/todo/hack comment to
note that this is not ideal, to minimize the chance that doing this
sort of thing spreads, could be good though.

> +	return;
> +    }
> +
> +    return $class->SUPER::write_config($vmid, $conf);
> +}
> +
>  # END implemented abstract methods from PVE::AbstractConfig
>  
>  sub has_cloudinit {