Merge pull request google#1473 from jimmidyson/prom-collector-label-spaces

Switch to Prometheus decoders for Prometheus custom metric endpoint parsing

Author: jimmidyson

collector/prometheus_collector.go

@@ -15,15 +15,18 @@
 package collector
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
-	"math"
+	"io"
 	"net/http"
-	"strconv"
-	"strings"
+	"sort"
 	"time"
 
+	rawmodel "github.com/prometheus/client_model/go"
+	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/common/model"
+
 	"github.com/google/cadvisor/container"
 	"github.com/google/cadvisor/info/v1"
 )
@@ -100,62 +103,104 @@ func (collector *PrometheusCollector) Name() string {
 	return collector.name
 }
 
-func getMetricData(line string) string {
-	fields := strings.Fields(line)
-	data := fields[3]
-	if len(fields) > 4 {
-		for i := range fields {
-			if i > 3 {
-				data = data + "_" + fields[i]
-			}
-		}
-	}
-	return strings.TrimSpace(data)
-}
-
 func (collector *PrometheusCollector) GetSpec() []v1.MetricSpec {
-	specs := []v1.MetricSpec{}
 
 	response, err := collector.httpClient.Get(collector.configFile.Endpoint.URL)
 	if err != nil {
-		return specs
+		return nil
 	}
 	defer response.Body.Close()
 
-	pageContent, err := ioutil.ReadAll(response.Body)
-	if err != nil {
-		return specs
+	if response.StatusCode != http.StatusOK {
+		return nil
 	}
 
-	lines := strings.Split(string(pageContent), "\n")
-	lineCount := len(lines)
-	for i, line := range lines {
-		if strings.HasPrefix(line, "# HELP") {
-			if i+2 >= lineCount {
-				break
-			}
+	dec := expfmt.NewDecoder(response.Body, expfmt.ResponseFormat(response.Header))
 
-			stopIndex := strings.IndexAny(lines[i+2], "{ ")
-			if stopIndex == -1 {
-				continue
-			}
+	var specs []v1.MetricSpec
 
-			name := strings.TrimSpace(lines[i+2][0:stopIndex])
-			if _, ok := collector.metricsSet[name]; collector.metricsSet != nil && !ok {
-				continue
-			}
-			spec := v1.MetricSpec{
-				Name:   name,
-				Type:   v1.MetricType(getMetricData(lines[i+1])),
-				Format: "float",
-				Units:  getMetricData(lines[i]),
-			}
-			specs = append(specs, spec)
+	for {
+		d := rawmodel.MetricFamily{}
+		if err = dec.Decode(&d); err != nil {
+			break
 		}
+		name := d.GetName()
+		if len(name) == 0 {
+			continue
+		}
+		// If metrics to collect is specified, skip any metrics not in the list to collect.
+		if _, ok := collector.metricsSet[name]; collector.metricsSet != nil && !ok {
+			continue
+		}
+
+		spec := v1.MetricSpec{
+			Name:   name,
+			Type:   metricType(d.GetType()),
+			Format: v1.FloatType,
+		}
+		specs = append(specs, spec)
 	}
+
+	if err != nil && err != io.EOF {
+		return nil
+	}
+
 	return specs
 }
 
+// metricType converts Prometheus metric type to cadvisor metric type.
+// If there is no mapping then just return the name of the Prometheus metric type.
+func metricType(t rawmodel.MetricType) v1.MetricType {
+	switch t {
+	case rawmodel.MetricType_COUNTER:
+		return v1.MetricCumulative
+	case rawmodel.MetricType_GAUGE:
+		return v1.MetricGauge
+	default:
+		return v1.MetricType(t.String())
+	}
+}
+
+type prometheusLabels []*rawmodel.LabelPair
+
+func labelSetToLabelPairs(labels model.Metric) prometheusLabels {
+	var promLabels prometheusLabels
+	for k, v := range labels {
+		name := string(k)
+		value := string(v)
+		promLabels = append(promLabels, &rawmodel.LabelPair{Name: &name, Value: &value})
+	}
+	return promLabels
+}
+
+func (s prometheusLabels) Len() int      { return len(s) }
+func (s prometheusLabels) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+
+// ByName implements sort.Interface by providing Less and using the Len and
+// Swap methods of the embedded PrometheusLabels value.
+type byName struct{ prometheusLabels }
+
+func (s byName) Less(i, j int) bool {
+	return s.prometheusLabels[i].GetName() < s.prometheusLabels[j].GetName()
+}
+
+func prometheusLabelSetToCadvisorLabel(promLabels model.Metric) string {
+	labels := labelSetToLabelPairs(promLabels)
+	sort.Sort(byName{labels})
+	var b bytes.Buffer
+
+	for i, l := range labels {
+		if i > 0 {
+			b.WriteString("\xff")
+		}
+		b.WriteString(l.GetName())
+		b.WriteString("=")
+		b.WriteString(l.GetValue())
+	}
+
+	return string(b.Bytes())
+}
+
 //Returns collected metrics and the next collection time of the collector
 func (collector *PrometheusCollector) Collect(metrics map[string][]v1.MetricVal) (time.Time, map[string][]v1.MetricVal, error) {
 	currentTime := time.Now()
@@ -168,59 +213,61 @@ func (collector *PrometheusCollector) Collect(metrics map[string][]v1.MetricVal)
 	}
 	defer response.Body.Close()
 
-	pageContent, err := ioutil.ReadAll(response.Body)
-	if err != nil {
-		return nextCollectionTime, nil, err
+	if response.StatusCode != http.StatusOK {
+		return nextCollectionTime, nil, fmt.Errorf("server returned HTTP status %s", response.Status)
 	}
 
-	var errorSlice []error
-	lines := strings.Split(string(pageContent), "\n")
-
-	newMetrics := make(map[string][]v1.MetricVal)
+	sdec := expfmt.SampleDecoder{
+		Dec: expfmt.NewDecoder(response.Body, expfmt.ResponseFormat(response.Header)),
+		Opts: &expfmt.DecodeOptions{
+			Timestamp: model.TimeFromUnixNano(currentTime.UnixNano()),
+		},
+	}
 
-	for _, line := range lines {
-		if line == "" {
+	var (
+		// 50 is chosen as a reasonable guesstimate at a number of metrics we can
+		// expect from virtually any endpoint to try to save allocations.
+		decSamples = make(model.Vector, 0, 50)
+		newMetrics = make(map[string][]v1.MetricVal)
+	)
+	for {
+		if err = sdec.Decode(&decSamples); err != nil {
 			break
 		}
-		if !strings.HasPrefix(line, "# HELP") && !strings.HasPrefix(line, "# TYPE") {
-			var metLabel string
-			startLabelIndex := strings.Index(line, "{")
-			spaceIndex := strings.Index(line, " ")
-			if startLabelIndex == -1 {
-				startLabelIndex = spaceIndex
-			}
 
-			metName := strings.TrimSpace(line[0:startLabelIndex])
-			if _, ok := collector.metricsSet[metName]; collector.metricsSet != nil && !ok {
+		for _, sample := range decSamples {
+			metName := string(sample.Metric[model.MetricNameLabel])
+			if len(metName) == 0 {
 				continue
 			}
-
-			if startLabelIndex+1 <= spaceIndex-1 {
-				metLabel = strings.TrimSpace(line[(startLabelIndex + 1):(spaceIndex - 1)])
-			}
-
-			metVal, err := strconv.ParseFloat(line[spaceIndex+1:], 64)
-			if err != nil {
-				errorSlice = append(errorSlice, err)
-			}
-			if math.IsNaN(metVal) {
-				metVal = 0
+			// If metrics to collect is specified, skip any metrics not in the list to collect.
+			if _, ok := collector.metricsSet[metName]; collector.metricsSet != nil && !ok {
+				continue
 			}
+			// TODO Handle multiple labels nicer. Prometheus metrics can have multiple
+			// labels, cadvisor only accepts a single string for the metric label.
+			label := prometheusLabelSetToCadvisorLabel(sample.Metric)
 
 			metric := v1.MetricVal{
-				Label:      metLabel,
-				FloatValue: metVal,
-				Timestamp:  currentTime,
+				FloatValue: float64(sample.Value),
+				Timestamp:  sample.Timestamp.Time(),
+				Label:      label,
 			}
 			newMetrics[metName] = append(newMetrics[metName], metric)
 			if len(newMetrics) > collector.metricCountLimit {
 				return nextCollectionTime, nil, fmt.Errorf("too many metrics to collect")
 			}
 		}
+		decSamples = decSamples[:0]
+	}
+
+	if err != nil && err != io.EOF {
+		return nextCollectionTime, nil, err
 	}
+
 	for key, val := range newMetrics {
 		metrics[key] = append(metrics[key], val...)
 	}
 
-	return nextCollectionTime, metrics, compileErrors(errorSlice)
+	return nextCollectionTime, metrics, nil
 }

collector/prometheus_collector_test.go

@@ -36,21 +36,29 @@ func TestPrometheus(t *testing.T) {
 	containerHandler := containertest.NewMockContainerHandler("mockContainer")
 	collector, err := NewPrometheusCollector("Prometheus", configFile, 100, containerHandler, http.DefaultClient)
 	assert.NoError(err)
-	assert.Equal(collector.name, "Prometheus")
-	assert.Equal(collector.configFile.Endpoint.URL, "http://localhost:8080/metrics")
+	assert.Equal("Prometheus", collector.name)
+	assert.Equal("http://localhost:8080/metrics", collector.configFile.Endpoint.URL)
 
 	tempServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 
-		text := "# HELP go_gc_duration_seconds A summary of the GC invocation durations.\n"
-		text += "# TYPE go_gc_duration_seconds summary\n"
-		text += "go_gc_duration_seconds{quantile=\"0\"} 5.8348000000000004e-05\n"
-		text += "go_gc_duration_seconds{quantile=\"1\"} 0.000499764\n"
-		text += "# HELP go_goroutines Number of goroutines that currently exist.\n"
-		text += "# TYPE go_goroutines gauge\n"
-		text += "go_goroutines 16\n"
-		text += "# HELP empty_metric A metric without any values\n"
-		text += "# TYPE empty_metric counter\n"
-		text += "\n"
+		text := `# HELP go_gc_duration_seconds A summary of the GC invocation durations.
+# TYPE go_gc_duration_seconds summary
+go_gc_duration_seconds{quantile="0"} 5.8348000000000004e-05
+go_gc_duration_seconds{quantile="1"} 0.000499764
+go_gc_duration_seconds_sum 1.7560473e+07
+go_gc_duration_seconds_count 2693
+# HELP go_goroutines Number of goroutines that currently exist.
+# TYPE go_goroutines gauge
+go_goroutines 16
+# HELP empty_metric A metric without any values
+# TYPE empty_metric counter
+# HELP metric_with_spaces_in_label A metric with spaces in a label.
+# TYPE metric_with_spaces_in_label gauge
+metric_with_spaces_in_label{name="Network Agent"} 72
+# HELP metric_with_multiple_labels A metric with multiple labels.
+# TYPE metric_with_multiple_labels gauge
+metric_with_multiple_labels{label1="One", label2="Two", label3="Three"} 81
+`
 		fmt.Fprintln(w, text)
 	}))
 
@@ -60,21 +68,47 @@ func TestPrometheus(t *testing.T) {
 
 	var spec []v1.MetricSpec
 	require.NotPanics(t, func() { spec = collector.GetSpec() })
-	assert.Len(spec, 2)
-	assert.Equal(spec[0].Name, "go_gc_duration_seconds")
-	assert.Equal(spec[1].Name, "go_goroutines")
+	assert.Len(spec, 4)
+	specNames := make(map[string]struct{}, 3)
+	for _, s := range spec {
+		specNames[s.Name] = struct{}{}
+	}
+	expectedSpecNames := map[string]struct{}{
+		"go_gc_duration_seconds":      {},
+		"go_goroutines":               {},
+		"metric_with_spaces_in_label": {},
+		"metric_with_multiple_labels": {},
+	}
+	assert.Equal(expectedSpecNames, specNames)
 
 	metrics := map[string][]v1.MetricVal{}
 	_, metrics, errMetric := collector.Collect(metrics)
 
 	assert.NoError(errMetric)
 
 	go_gc_duration := metrics["go_gc_duration_seconds"]
-	assert.Equal(go_gc_duration[0].FloatValue, 5.8348000000000004e-05)
-	assert.Equal(go_gc_duration[1].FloatValue, 0.000499764)
+	assert.Equal(5.8348000000000004e-05, go_gc_duration[0].FloatValue)
+	assert.Equal("__name__=go_gc_duration_seconds\xffquantile=0", go_gc_duration[0].Label)
+	assert.Equal(0.000499764, go_gc_duration[1].FloatValue)
+	assert.Equal("__name__=go_gc_duration_seconds\xffquantile=1", go_gc_duration[1].Label)
+	go_gc_duration_sum := metrics["go_gc_duration_seconds_sum"]
+	assert.Equal(1.7560473e+07, go_gc_duration_sum[0].FloatValue)
+	assert.Equal("__name__=go_gc_duration_seconds_sum", go_gc_duration_sum[0].Label)
+	go_gc_duration_count := metrics["go_gc_duration_seconds_count"]
+	assert.Equal(2693, go_gc_duration_count[0].FloatValue)
+	assert.Equal("__name__=go_gc_duration_seconds_count", go_gc_duration_count[0].Label)
 
 	goRoutines := metrics["go_goroutines"]
-	assert.Equal(goRoutines[0].FloatValue, 16)
+	assert.Equal(16, goRoutines[0].FloatValue)
+	assert.Equal("__name__=go_goroutines", goRoutines[0].Label)
+
+	metricWithSpaces := metrics["metric_with_spaces_in_label"]
+	assert.Equal(72, metricWithSpaces[0].FloatValue)
+	assert.Equal("__name__=metric_with_spaces_in_label\xffname=Network Agent", metricWithSpaces[0].Label)
+
+	metricWithMultipleLabels := metrics["metric_with_multiple_labels"]
+	assert.Equal(81, metricWithMultipleLabels[0].FloatValue)
+	assert.Equal("__name__=metric_with_multiple_labels\xfflabel1=One\xfflabel2=Two\xfflabel3=Three", metricWithMultipleLabels[0].Label)
 }
 
 func TestPrometheusEndpointConfig(t *testing.T) {
@@ -158,13 +192,16 @@ func TestPrometheusFiltersMetrics(t *testing.T) {
 
 	tempServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 
-		text := "# HELP go_gc_duration_seconds A summary of the GC invocation durations.\n"
-		text += "# TYPE go_gc_duration_seconds summary\n"
-		text += "go_gc_duration_seconds{quantile=\"0\"} 5.8348000000000004e-05\n"
-		text += "go_gc_duration_seconds{quantile=\"1\"} 0.000499764\n"
-		text += "# HELP go_goroutines Number of goroutines that currently exist.\n"
-		text += "# TYPE go_goroutines gauge\n"
-		text += "go_goroutines 16"
+		text := `# HELP go_gc_duration_seconds A summary of the GC invocation durations.
+# TYPE go_gc_duration_seconds summary
+go_gc_duration_seconds{quantile="0"} 5.8348000000000004e-05
+go_gc_duration_seconds{quantile="1"} 0.000499764
+go_gc_duration_seconds_sum 1.7560473e+07
+go_gc_duration_seconds_count 2693
+# HELP go_goroutines Number of goroutines that currently exist.
+# TYPE go_goroutines gauge
+go_goroutines 16
+`
 		fmt.Fprintln(w, text)
 	}))