Ignore objects with names that end with / when listing rule groups

CHANGELOG.md

@@ -21,6 +21,7 @@
 * [BUGFIX] Distributor: reverted changes done to rate limiting in #3825. #3948
 * [BUGFIX] Ingester: Fix race condition when opening and closing tsdb concurrently. #3959
 * [BUGFIX] Querier: streamline tracing spans. #3924
+* [BUGFIX] Ruler Storage: ignore objects with empty namespace or group in the name. #3999
 
 ## 1.8.0 in progress
 

pkg/ruler/rulestore/bucketclient/bucket_client.go

@@ -102,9 +102,16 @@ func (b *BucketRuleStore) ListAllRuleGroups(ctx context.Context) (map[string]rul
 
 	// List rule groups for all tenants.
 	err := b.bucket.Iter(ctx, "", func(key string) error {
+		// Ignore objects that look like directories, ie. they have empty namespace or group name.
+		// Such objects can exist in the object store, but would cause trouble when loading them, because
+		// we check for user, namespace and group components not being empty.
+		if strings.HasSuffix(key, objstore.DirDelim) {
+			return nil
+		}
+
 		userID, namespace, group, err := parseRuleGroupObjectKeyWithUser(key)
 		if err != nil {
-			level.Warn(b.logger).Log("msg", "invalid rule group object key found while listing rule groups", "key", key)
+			level.Warn(b.logger).Log("msg", "invalid rule group object key found while listing rule groups", "key", key, "err", err)
 
 			// Do not fail just because of a spurious item in the bucket.
 			return nil

pkg/ruler/rulestore/bucketclient/bucket_client_test.go

@@ -374,3 +374,36 @@ func TestParseRuleGroupObjectKeyWithUser(t *testing.T) {
 		})
 	}
 }
+
+func TestListAllRuleGroupsWithNoNamespaceOrGroup(t *testing.T) {
+	obj := mockBucket{
+		names: []string{
+			"rules/user1/",
+			"rules/user2/bnM=/",         // namespace "ns", ends with '/'
+			"rules/user3/bnM=/Z3JvdXAx", // namespace "ns", group "group1"
+		},
+	}
+
+	s := NewBucketRuleStore(obj, nil, log.NewNopLogger())
+	out, err := s.ListAllRuleGroups(context.Background())
+	require.NoError(t, err)
+
+	require.Equal(t, 1, len(out))                    // one user
+	require.Equal(t, 1, len(out["user3"]))           // one group
+	require.Equal(t, "group1", out["user3"][0].Name) // one group
+}
+
+type mockBucket struct {
+	objstore.Bucket
+
+	names []string
+}
+
+func (mb mockBucket) Iter(ctx context.Context, dir string, f func(string) error, options ...objstore.IterOption) error {
+	for _, n := range mb.names {
+		if err := f(n); err != nil {
+			return err
+		}
+	}
+	return nil
+}