[PATCH proxmox-backup 2/2] fix #7198: metric collection: count veth uplink when running in a container

[Jakob Klocker <j.klocker@proxmox.com>]

When PBS runs inside an LXC container, the network uplink is one end of
a veth pair rather than a physical NIC, so is_physical() returns false
and the interface is excluded from network utilization stats unless its
name happens to match PHYSICAL_NIC_REGEX. This drops graph data for
interfaces with custom names (e.g. wan0).

Check whether we are running in a container (via /run/systemd/container,
cached in a OnceLock) and, if so, also count veth interfaces as physical
for metric collection. This mirrors how a VM's NIC is already counted.

Link: https://bugzilla.proxmox.com/show_bug.cgi?id=7198
Signed-off-by: Jakob Klocker <j.klocker@proxmox.com>
---
 src/server/metric_collection/mod.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/server/metric_collection/mod.rs b/src/server/metric_collection/mod.rs
index 18625b1a5..47882eb89 100644
--- a/src/server/metric_collection/mod.rs
+++ b/src/server/metric_collection/mod.rs
@@ -148,6 +148,11 @@ impl NetdevStat {
 }
 
 static NETWORK_INTERFACE_CACHE: OnceLock<HashMap<String, IpLink>> = OnceLock::new();
+static IN_CONTAINER_CACHE: OnceLock<bool> = OnceLock::new();
+
+fn running_in_container() -> bool {
+    Path::new("/run/systemd/container").exists()
+}
 
 fn collect_netdev_stats() -> Option<Vec<NetdevStat>> {
     use proxmox_sys::linux::procfs::read_proc_net_dev;
@@ -175,10 +180,11 @@ fn collect_netdev_stats() -> Option<Vec<NetdevStat>> {
     };
 
     let mut stat_devs = Vec::with_capacity(net_devs.len());
+    let in_container = *IN_CONTAINER_CACHE.get_or_init(running_in_container);
 
     for net_dev in net_devs {
         if let Some(ip_link) = ip_links.get(&net_dev.device) {
-            let ty = if ip_link.is_physical() {
+            let ty = if ip_link.is_physical() || (in_container && ip_link.is_veth()) {
                 NetdevType::Physical
             } else {
                 NetdevType::Virtual
-- 
2.47.3