More userfriendly output when we fail to create the tiered storage.

main.go

@@ -48,7 +48,10 @@ func main() {
 		log.Fatalf("Error loading configuration from %s: %v", *configFile, err)
 	}
 
-	ts := metric.NewTieredStorage(5000, 5000, 100, time.Second*30, time.Second*1, time.Second*20, *metricsStoragePath)
+	ts, err := metric.NewTieredStorage(5000, 5000, 100, time.Second*30, time.Second*1, time.Second*20, *metricsStoragePath)
+	if err != nil {
+		log.Fatalf("Error opening storage: %s", err)
+	}
 	go ts.Serve()
 	go func() {
 		notifier := make(chan os.Signal)

rules/rules_test.go

@@ -214,7 +214,10 @@ func vectorComparisonString(expected []string, actual []string) string {
 func TestExpressions(t *testing.T) {
 	temporaryDirectory := test.NewTemporaryDirectory("rule_expression_tests", t)
 	defer temporaryDirectory.Close()
-	tieredStorage := metric.NewTieredStorage(5000, 5000, 100, time.Second*30, time.Second*1, time.Second*20, temporaryDirectory.Path())
+	tieredStorage, err := metric.NewTieredStorage(5000, 5000, 100, time.Second*30, time.Second*1, time.Second*20, temporaryDirectory.Path())
+	if err != nil {
+		t.Fatalf("Error opening storage: %s", err)
+	}
 	go tieredStorage.Serve()
 
 	ast.SetStorage(tieredStorage)

storage/metric/tiered.go

@@ -73,13 +73,13 @@ type Storage interface {
 	GetMetricForFingerprint(model.Fingerprint) (m *model.Metric, err error)
 }
 
-func NewTieredStorage(appendToMemoryQueueDepth, appendToDiskQueueDepth, viewQueueDepth uint, flushMemoryInterval, writeMemoryInterval, memoryTTL time.Duration, root string) Storage {
+func NewTieredStorage(appendToMemoryQueueDepth, appendToDiskQueueDepth, viewQueueDepth uint, flushMemoryInterval, writeMemoryInterval, memoryTTL time.Duration, root string) (storage Storage, err error) {
 	diskStorage, err := NewLevelDBMetricPersistence(root)
 	if err != nil {
-		panic(err)
+		return
 	}
 
-	return &tieredStorage{
+	storage = &tieredStorage{
 		appendToDiskQueue:   make(chan model.Sample, appendToDiskQueueDepth),
 		appendToMemoryQueue: make(chan model.Sample, appendToMemoryQueueDepth),
 		diskStorage:         diskStorage,
@@ -90,6 +90,7 @@ func NewTieredStorage(appendToMemoryQueueDepth, appendToDiskQueueDepth, viewQueu
 		viewQueue:           make(chan viewJob, viewQueueDepth),
 		writeMemoryInterval: writeMemoryInterval,
 	}
+	return
 }
 
 func (t *tieredStorage) AppendSample(s model.Sample) (err error) {

storage/metric/tiered_test.go

@@ -35,10 +35,14 @@ func (t testTieredStorageCloser) Close() {
 func newTestTieredStorage(t test.Tester) (storage Storage, closer test.Closer) {
 	var directory test.TemporaryDirectory
 	directory = test.NewTemporaryDirectory("test_tiered_storage", t)
-	storage = NewTieredStorage(5000000, 2500, 1000, 5*time.Second, 15*time.Second, 0*time.Second, directory.Path())
+	storage, err := NewTieredStorage(5000000, 2500, 1000, 5*time.Second, 15*time.Second, 0*time.Second, directory.Path())
+
+	if err != nil {
+		t.Fatalf("Error creating storage: %s", err)
+	}
 
 	if storage == nil {
-		t.Fatalf("%d. storage == nil")
+		t.Fatalf("storage == nil")
 	}
 
 	go storage.Serve()