[pbs-devel] [PATCH proxmox-backup] server: push: log encountered empty backup groups during sync

[Christian Ebner]

Log also empty backup groups with no snapshots encountered during the
sync so the log output contains this additional information as well,
reducing possible confusion.

Nevertheless, continue with the regular logic, so that pruning of
vanished snapshot is honored.

Examplary output in the sync jobs task log:
```
2024-11-22T18:32:40+01:00: Syncing datastore 'datastore', root namespace into datastore 'push-target-store', namespace 'test'
2024-11-22T18:32:40+01:00: Found 2 groups to sync (out of 2 total)
2024-11-22T18:32:40+01:00: skipped: 1 snapshot(s) (2024-11-22T13:40:18Z) - older than the newest snapshot present on sync target
2024-11-22T18:32:40+01:00: Group 'vm/200' contains no snapshots to sync to remote
2024-11-22T18:32:40+01:00: Finished syncing root namespace, current progress: 1 groups, 0 snapshots
```

Reported-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 src/server/push.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/server/push.rs b/src/server/push.rs
index 082a6f49d..99757a3cc 100644
--- a/src/server/push.rs
+++ b/src/server/push.rs
@@ -664,6 +664,10 @@ pub(crate) async fn push_group(
     let mut snapshots: Vec<BackupDir> = params.source.list_backup_dirs(namespace, group).await?;
     snapshots.sort_unstable_by(|a, b| a.time.cmp(&b.time));
 
+    if snapshots.is_empty() {
+        info!("Group '{group}' contains no snapshots to sync to remote");
+    }
+
     let total_snapshots = snapshots.len();
     let cutoff = params
         .transfer_last
-- 
2.39.5