[pve-devel] [PATCH network] sdn: write frr config if the frr.conf.local file exists

[Stefan Hanreich]

Tested this on my machine, works as advertised. The general idea of
regenerating the FRR config anytime we reload SDN also makes sense to
me, since it allows users to have a FRR config and potentially create
controllers / fabrics at a later time and not have to worry about their
frr.conf getting overwritten accidentally.

Reviewed-by: Stefan Hanreich <s.hanreich at proxmox.com>
Tested-by: Stefan Hanreich <s.hanreich at proxmox.com>


On 9/19/25 3:25 PM, Gabriel Goller wrote:
> Currently we check if there is a fabric or a controller existing to
> decide if we write the frr.conf file. Also add a check if the
> frr.conf.local exists. This way it's possible to have a custom config in
> the frr.conf.local file without any SDN objects configured and still
> be able to apply the config.
> By not checking the content we can also clear the frr config by clearing
> the frr.conf.local file.
> 
> Reported-by: Hannes Dürr <h.duerr at proxmox.com>
> Signed-off-by: Gabriel Goller <g.goller at proxmox.com>
> ---
>  src/PVE/Network/SDN.pm     |  3 ++-
>  src/PVE/Network/SDN/Frr.pm | 20 ++++++++++++++++++--
>  2 files changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/src/PVE/Network/SDN.pm b/src/PVE/Network/SDN.pm
> index f2ecd4ab7318..e867d1ab886e 100644
> --- a/src/PVE/Network/SDN.pm
> +++ b/src/PVE/Network/SDN.pm
> @@ -123,8 +123,9 @@ sub running_config_has_frr {
>      # both can be empty if the SDN configuration was never applied
>      my $controllers = $running_config->{controllers}->{ids} // {};
>      my $fabrics = $running_config->{fabrics}->{ids} // {};
> +    my $local_frr_config = PVE::Network::SDN::Frr::local_frr_config_exists();
>  
> -    return %$controllers || %$fabrics;
> +    return %$controllers || %$fabrics || $local_frr_config;
>  }
>  
>  sub pending_config {
> diff --git a/src/PVE/Network/SDN/Frr.pm b/src/PVE/Network/SDN/Frr.pm
> index b607b32c248d..e77eba182177 100644
> --- a/src/PVE/Network/SDN/Frr.pm
> +++ b/src/PVE/Network/SDN/Frr.pm
> @@ -32,6 +32,22 @@ string that is a FRR configuration line.
>  use PVE::RESTEnvironment qw(log_warn);
>  use PVE::Tools qw(file_get_contents file_set_contents run_command);
>  
> +my $FRR_CONF_LOCAL_FILE = "/etc/frr/frr.conf.local";
> +
> +=head3 local_frr_config_exists
> +
> +Returns true if the `/etc/frr/frr.conf.local` file exists, otherwise false.
> +
> +=cut
> +
> +sub local_frr_config_exists {
> +    if (-e $FRR_CONF_LOCAL_FILE) {
> +        return 1;
> +    } else {
> +        return 0;
> +    }
> +}
> +
>  =head3 read_local_frr_config
>  
>  Returns the contents of `/etc/frr/frr.conf.local` as a string if it exists, otherwise undef.
> @@ -39,8 +55,8 @@ Returns the contents of `/etc/frr/frr.conf.local` as a string if it exists, othe
>  =cut
>  
>  sub read_local_frr_config {
> -    if (-e "/etc/frr/frr.conf.local") {
> -        return file_get_contents("/etc/frr/frr.conf.local");
> +    if (-e $FRR_CONF_LOCAL_FILE) {

small nit: potentially use the helper here, if we define one anyway?

+        return file_get_contents($FRR_CONF_LOCAL_FILE);
>      }
>  }
>