Add config to specify custom prefix of metrics

stackdriver.go

@@ -52,6 +52,7 @@ type Sink struct {
 
 	bucketer  BucketFn
 	extractor ExtractLabelsFn
+	prefix    string
 	taskInfo  *taskInfo
 
 	mu        sync.Mutex
@@ -69,6 +70,9 @@ type Config struct {
 	// variable parameters within a metric name.
 	// Optional. Defaults to DefaultLabelExtractor.
 	LabelExtractor ExtractLabelsFn
+	// Prefix of the metrics recorded. Defaults to "go-metrics/" so your metric "foo" will be recorded as
+	// "custom.googleapis.com/go-metrics/foo".
+	Prefix *string
 	// The bucketer is used to determine histogram bucket boundaries
 	// for the sampled metrics. This will execute before the LabelExtractor.
 	// Optional. Defaults to DefaultBucketer.
@@ -147,6 +151,7 @@ func NewSink(client *monitoring.MetricClient, config *Config) *Sink {
 	s := &Sink{
 		client:    client,
 		extractor: config.LabelExtractor,
+		prefix:    "go-metrics/",
 		bucketer:  config.Bucketer,
 		interval:  config.ReportingInterval,
 		taskInfo: &taskInfo{
@@ -159,6 +164,13 @@ func NewSink(client *monitoring.MetricClient, config *Config) *Sink {
 		debugLogs: config.DebugLogs,
 	}
 
+	if config.Prefix != nil {
+		if isValidMetricsPrefix(*config.Prefix) {
+			s.prefix = *config.Prefix
+		} else {
+			log.Printf("%s is not valid string to be used as metrics name, using default value 'go-metrics/'", *config.Prefix)
+		}
+	}
 	// apply defaults if not configured explicitly
 	if s.extractor == nil {
 		s.extractor = DefaultLabelExtractor
@@ -207,6 +219,12 @@ func NewSink(client *monitoring.MetricClient, config *Config) *Sink {
 	return s
 }
 
+func isValidMetricsPrefix(s string) bool {
+	// start with alphanumeric, can contain underscore in path (expect first char), slash is used to separate path.
+	match, err := regexp.MatchString("^(?:[a-z0-9](?:[a-z0-9_]*)/?)*$", s)
+	return err == nil && match
+}
+
 func (s *Sink) flushMetrics(ctx context.Context) {
 	if s.interval == 0*time.Second {
 		return
@@ -297,7 +315,7 @@ func (s *Sink) report(ctx context.Context) {
 		}
 		ts = append(ts, &monitoringpb.TimeSeries{
 			Metric: &metricpb.Metric{
-				Type:   path.Join("custom.googleapis.com", "go-metrics", name),
+				Type:   fmt.Sprintf("custom.googleapis.com/%s%s", s.prefix, name),
 				Labels: labels,
 			},
 			MetricKind: metric.MetricDescriptor_GAUGE,
@@ -330,7 +348,7 @@ func (s *Sink) report(ctx context.Context) {
 		}
 		ts = append(ts, &monitoringpb.TimeSeries{
 			Metric: &metricpb.Metric{
-				Type:   path.Join("custom.googleapis.com", "go-metrics", name),
+				Type:   fmt.Sprintf("custom.googleapis.com/%s%s", s.prefix, name),
 				Labels: labels,
 			},
 			MetricKind: metric.MetricDescriptor_GAUGE,
@@ -370,7 +388,7 @@ func (s *Sink) report(ctx context.Context) {
 
 		ts = append(ts, &monitoringpb.TimeSeries{
 			Metric: &metricpb.Metric{
-				Type:   path.Join("custom.googleapis.com", "go-metrics", name),
+				Type:   fmt.Sprintf("custom.googleapis.com/%s%s", s.prefix, name),
 				Labels: labels,
 			},
 			MetricKind: metric.MetricDescriptor_CUMULATIVE,

stackdriver_test.go

@@ -91,6 +91,93 @@ func BenchmarkReport10(b *testing.B)  { benchmarkCopy(10, 10, 10, b) }
 func BenchmarkReport50(b *testing.B)  { benchmarkCopy(50, 50, 50, b) }
 func BenchmarkReport100(b *testing.B) { benchmarkCopy(100, 100, 100, b) }
 
+func sPtr(s string) *string {
+	return &s
+}
+
+func TestNewSinkSetCustomPrefix(t *testing.T) {
+	tests := []struct {
+		name           string
+		configPrefix   *string
+		expectedPrefix string
+	}{
+		{
+			name:           "default to go-metrics/",
+			expectedPrefix: "go-metrics/",
+		},
+		{
+			name:           "set custom",
+			configPrefix:   sPtr("cuSt0m_metrics"),
+			expectedPrefix: "cuSt0m_metrics",
+		},
+		{
+			name:           "default to go-metrics/ when given prefix is invalid",
+			configPrefix:   sPtr("___"),
+			expectedPrefix: "go-metrics/",
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			ss := NewSink(nil, &Config{Prefix: tc.configPrefix})
+
+			if ss.prefix != tc.expectedPrefix {
+				t.Errorf("prefix should be initalized as '" + tc.expectedPrefix + "' but got " + ss.prefix)
+			}
+		})
+	}
+}
+
+func TestIsValidMetricsPrefix(t *testing.T) {
+	tests := []struct {
+		prefix        string
+		expectedValid bool
+	}{
+		{
+			prefix:        "",
+			expectedValid: true,
+		},
+		{
+			prefix:        "a",
+			expectedValid: true,
+		},
+		{
+			prefix:        "abc/bef/",
+			expectedValid: true,
+		},
+		{
+			prefix:        "aa_",
+			expectedValid: true,
+		},
+		{
+			prefix:        "///",
+			expectedValid: false,
+		},
+		{
+			prefix:        "!",
+			expectedValid: false,
+		},
+		{
+			prefix:        "_aa",
+			expectedValid: false,
+		},
+		{
+			prefix:        "日本語",
+			expectedValid: false,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.prefix, func(t *testing.T) {
+			if isValidMetricsPrefix(tc.prefix) != tc.expectedValid {
+				if tc.expectedValid {
+					t.Errorf("expected %s to be valid", tc.prefix)
+				} else {
+					t.Errorf("expected %s to be invalid", tc.prefix)
+				}
+			}
+		})
+	}
+}
+
 func TestSample(t *testing.T) {
 	ss := newTestSink(0*time.Second, nil)
 
@@ -943,6 +1030,7 @@ func newTestSink(interval time.Duration, client *monitoring.MetricClient) *Sink
 	s.taskInfo = &taskInfo{
 		ProjectID: "foo",
 	}
+	s.prefix = "go-metrics/"
 	s.interval = interval
 	s.bucketer = DefaultBucketer
 	s.extractor = DefaultLabelExtractor