Change internal metric name label to __name__.

This also adds a check that forbids any user-supplied metrics to start
with the reserved label name prefix "__".

Change-Id: I2fe94c740b685ad05c4c670613cf2af7b9e1c1c0

extraction/fixtures/test0_0_1-0_0_2.json

@@ -1,7 +1,7 @@
 [
   {
     "baseLabels": {
-      "name": "rpc_calls_total",
+      "__name__": "rpc_calls_total",
       "job": "batch_job"
     },
     "docstring": "RPC calls.",
@@ -31,7 +31,7 @@
   },
   {
     "baseLabels": {
-      "name": "rpc_latency_microseconds"
+      "__name__": "rpc_latency_microseconds"
     },
       "docstring": "RPC latency.",
       "metric": {

extraction/metricfamilyprocessor_test.go

@@ -70,12 +70,12 @@ func TestMetricFamilyProcessor(t *testing.T) {
 				{
 					Samples: model.Samples{
 						&model.Sample{
-							Metric:    model.Metric{"name": "request_count", "some_label_name": "some_label_value"},
+							Metric:    model.Metric{model.MetricNameLabel: "request_count", "some_label_name": "some_label_value"},
 							Value:     -42,
 							Timestamp: testTime,
 						},
 						&model.Sample{
-							Metric:    model.Metric{"name": "request_count", "another_label_name": "another_label_value"},
+							Metric:    model.Metric{model.MetricNameLabel: "request_count", "another_label_name": "another_label_value"},
 							Value:     84,
 							Timestamp: testTime,
 						},
@@ -89,17 +89,17 @@ func TestMetricFamilyProcessor(t *testing.T) {
 				{
 					Samples: model.Samples{
 						&model.Sample{
-							Metric:    model.Metric{"name": "request_count", "some_label_name": "some_label_value", "quantile": "0.99"},
+							Metric:    model.Metric{model.MetricNameLabel: "request_count", "some_label_name": "some_label_value", "quantile": "0.99"},
 							Value:     -42,
 							Timestamp: testTime,
 						},
 						&model.Sample{
-							Metric:    model.Metric{"name": "request_count", "some_label_name": "some_label_value", "quantile": "0.999"},
+							Metric:    model.Metric{model.MetricNameLabel: "request_count", "some_label_name": "some_label_value", "quantile": "0.999"},
 							Value:     -84,
 							Timestamp: testTime,
 						},
 						&model.Sample{
-							Metric:    model.Metric{"name": "request_count", "another_label_name": "another_label_value", "quantile": "0.5"},
+							Metric:    model.Metric{model.MetricNameLabel: "request_count", "another_label_name": "another_label_value", "quantile": "0.5"},
 							Value:     10,
 							Timestamp: testTime,
 						},

model/labelname.go

@@ -23,7 +23,11 @@ const (
 	ExporterLabelPrefix LabelName = "exporter_"
 
 	// The label name indicating the metric name of a timeseries.
-	MetricNameLabel LabelName = "name"
+	MetricNameLabel LabelName = "__name__"
+
+	// ReservedLabelPrefix is a prefix which is not legal in user-supplied label
+	// names.
+	ReservedLabelPrefix = "__"
 
 	// The label name indicating the job from which a timeseries was scraped.
 	JobLabel LabelName = "job"

prometheus/constants.go

@@ -37,7 +37,6 @@ const (
 	baseLabelsKey = "baseLabels"
 	docstringKey  = "docstring"
 	metricKey     = "metric"
-	nameLabel     = "name"
 
 	counterTypeValue   = "counter"
 	floatBitCount      = 64

prometheus/registry.go

@@ -25,6 +25,7 @@ import (
 	"code.google.com/p/goprotobuf/proto"
 	"github.com/matttproud/golang_protobuf_extensions/ext"
 
+	"github.com/prometheus/client_golang/model"
 	"github.com/prometheus/client_golang/vendor/goautoneg"
 )
 
@@ -124,8 +125,9 @@ func (r *registry) isValidCandidate(name string, baseLabels map[string]string) (
 		}
 	}
 
-	if _, contains := baseLabels[nameLabel]; contains {
+	for label := range baseLabels {
-		err = fmt.Errorf("metric named %s with baseLabels %s contains reserved label name %s in baseLabels", name, baseLabels, nameLabel)
+		if strings.HasPrefix(label, model.ReservedLabelPrefix) {
+			err = fmt.Errorf("metric named %s with baseLabels %s contains reserved label name %s in baseLabels", name, baseLabels, label)
 
 			if *abortOnMisuse {
 				panic(err)
@@ -135,8 +137,9 @@ func (r *registry) isValidCandidate(name string, baseLabels map[string]string) (
 
 			return signature, err
 		}
+	}
 
-	baseLabels[nameLabel] = name
+	baseLabels[string(model.MetricNameLabel)] = name
 	signature = labelsToSignature(baseLabels)
 
 	if _, contains := r.signatureContainers[signature]; contains {

prometheus/registry_test.go

@@ -15,6 +15,8 @@ import (
 	"testing"
 
 	"code.google.com/p/goprotobuf/proto"
+
+	"github.com/prometheus/client_golang/model"
 )
 
 func testRegister(t tester) {
@@ -83,7 +85,7 @@ func testRegister(t tester) {
 			inputs: []input{
 				{
 					name:       "valid_name",
-					baseLabels: map[string]string{"name": "illegal_duplicate_name"},
+					baseLabels: map[string]string{model.ReservedLabelPrefix + "internal": "illegal_internal_name"},
 				},
 			},
 			outputs: []bool{
@@ -303,7 +305,7 @@ func testDumpToWriter(t tester) {
 					"foo": NewCounter(),
 				},
 			},
-			out: []byte(`[{"baseLabels":{"label_foo":"foo","name":"foo"},"docstring":"metric foo","metric":{"type":"counter","value":[]}}]`),
+			out: []byte(`[{"baseLabels":{"__name__":"foo","label_foo":"foo"},"docstring":"metric foo","metric":{"type":"counter","value":[]}}]`),
 		},
 		{
 			in: input{
@@ -312,7 +314,7 @@ func testDumpToWriter(t tester) {
 					"bar": NewCounter(),
 				},
 			},
-			out: []byte(`[{"baseLabels":{"label_bar":"bar","name":"bar"},"docstring":"metric bar","metric":{"type":"counter","value":[]}},{"baseLabels":{"label_foo":"foo","name":"foo"},"docstring":"metric foo","metric":{"type":"counter","value":[]}}]`),
+			out: []byte(`[{"baseLabels":{"__name__":"bar","label_bar":"bar"},"docstring":"metric bar","metric":{"type":"counter","value":[]}},{"baseLabels":{"__name__":"foo","label_foo":"foo"},"docstring":"metric foo","metric":{"type":"counter","value":[]}}]`),
 		},
 	}