fix: log download failed error (#3661)

Fixes #3659

pageserver/src/tenant/tasks.rs

@@ -74,7 +74,7 @@ async fn compaction_loop(tenant_id: TenantId) {
             let period = tenant.get_compaction_period();
 
             // TODO: we shouldn't need to await to find tenant and this could be moved outside of
-            // loop
+            // loop, #3501. There are also additional "allowed_errors" in tests.
             if first {
                 first = false;
                 if random_init_delay(period, &cancel).await.is_err() {

pageserver/src/tenant/timeline.rs

@@ -3745,6 +3745,7 @@ impl Timeline {
                     remote_layer.ongoing_download.close();
                 } else {
                     // Keep semaphore open. We'll drop the permit at the end of the function.
+                    info!("on-demand download failed: {:?}", result.as_ref().unwrap_err());
                 }
 
                 // Don't treat it as an error if the task that triggered the download

test_runner/regress/test_tenants.py

@@ -250,6 +250,10 @@ def test_pageserver_with_empty_tenants(
     env.pageserver.allowed_errors.append(
         ".*could not load tenant.*Failed to list timelines directory.*"
     )
+    # this is until #3501
+    env.pageserver.allowed_errors.append(
+        ".*Compaction failed, retrying in 2s: Cannot run compaction iteration on inactive tenant"
+    )
 
     client = env.pageserver.http_client()