Add Prometheus Collector

collector/config.go

@@ -48,3 +48,14 @@ type MetricConfig struct {
 	//the regular expression that can be used to extract the metric
 	Regex string `json:"regex"`
 }
+
+type Prometheus struct {
+	//the endpoint to hit to scrape metrics
+	Endpoint string `json:"endpoint"`
+
+	//the frequency at which metrics should be collected
+	PollingFrequency time.Duration `json:"polling_frequency"`
+
+	//holds names of different metrics that can be collected
+	MetricsConfig []string `json:"metrics_config"`
+}

collector/config/sample_config_prometheus.json

@@ -0,0 +1,6 @@
+{
+        "endpoint" : "http://localhost:8080/metrics",
+	"polling_frequency" : 10, 
+        "metrics_config" : [
+        ]
+}

collector/prometheus_collector.go

@@ -0,0 +1,166 @@
+// Copyright 2015 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/google/cadvisor/info/v1"
+)
+
+type PrometheusCollector struct {
+	//name of the collector
+	name string
+
+	//rate at which metrics are collected
+	pollingFrequency time.Duration
+
+	//holds information extracted from the config file for a collector
+	configFile Prometheus
+}
+
+//Returns a new collector using the information extracted from the configfile
+func NewPrometheusCollector(collectorName string, configFile []byte) (*PrometheusCollector, error) {
+	var configInJSON Prometheus
+	err := json.Unmarshal(configFile, &configInJSON)
+	if err != nil {
+		return nil, err
+	}
+
+	minPollingFrequency := configInJSON.PollingFrequency
+
+	// Minimum supported frequency is 1s
+	minSupportedFrequency := 1 * time.Second
+
+	if minPollingFrequency < minSupportedFrequency {
+		minPollingFrequency = minSupportedFrequency
+	}
+
+	//TODO : Add checks for validity of config file (eg : Accurate JSON fields)
+	return &PrometheusCollector{
+		name:             collectorName,
+		pollingFrequency: minPollingFrequency,
+		configFile:       configInJSON,
+	}, nil
+}
+
+//Returns name of the collector
+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 := http.Get(collector.configFile.Endpoint)
+	if err != nil {
+		return specs
+	}
+	defer response.Body.Close()
+
+	pageContent, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return specs
+	}
+
+	lines := strings.Split(string(pageContent), "\n")
+	for i, line := range lines {
+		if strings.HasPrefix(line, "# HELP") {
+			stopIndex := strings.Index(lines[i+2], "{")
+			if stopIndex == -1 {
+				stopIndex = strings.Index(lines[i+2], " ")
+			}
+			spec := v1.MetricSpec{
+				Name:   strings.TrimSpace(lines[i+2][0:stopIndex]),
+				Type:   v1.MetricType(getMetricData(lines[i+1])),
+				Format: "float",
+				Units:  getMetricData(lines[i]),
+			}
+			specs = append(specs, spec)
+		}
+	}
+	return specs
+}
+
+//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()
+	nextCollectionTime := currentTime.Add(time.Duration(collector.pollingFrequency))
+
+	uri := collector.configFile.Endpoint
+	response, err := http.Get(uri)
+	if err != nil {
+		return nextCollectionTime, nil, err
+	}
+	defer response.Body.Close()
+
+	pageContent, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return nextCollectionTime, nil, err
+	}
+
+	var errorSlice []error
+	lines := strings.Split(string(pageContent), "\n")
+
+	for _, line := range lines {
+		if line == "" {
+			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 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)
+			}
+
+			metric := v1.MetricVal{
+				Label:      metLabel,
+				FloatValue: metVal,
+				Timestamp:  currentTime,
+			}
+			metrics[metName] = append(metrics[metName], metric)
+		}
+	}
+	return nextCollectionTime, metrics, compileErrors(errorSlice)
+}

collector/prometheus_collector_test.go

@@ -0,0 +1,64 @@
+// Copyright 2015 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package collector
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/google/cadvisor/info/v1"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPrometheus(t *testing.T) {
+	assert := assert.New(t)
+
+	//Create a prometheus collector using the config file 'sample_config_prometheus.json'
+	configFile, err := ioutil.ReadFile("config/sample_config_prometheus.json")
+	collector, err := NewPrometheusCollector("Prometheus", configFile)
+	assert.NoError(err)
+	assert.Equal(collector.name, "Prometheus")
+	assert.Equal(collector.configFile.Endpoint, "http://localhost:8080/metrics")
+
+	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"
+		fmt.Fprintln(w, text)
+	}))
+
+	defer tempServer.Close()
+
+	collector.configFile.Endpoint = tempServer.URL
+	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)
+
+	goRoutines := metrics["go_goroutines"]
+	assert.Equal(goRoutines[0].FloatValue, 16)
+}

manager/manager.go

@@ -705,15 +705,28 @@ func (m *manager) registerCollectors(collectorConfigs map[string]string, cont *c
 		}
 		glog.V(3).Infof("Got config from %q: %q", v, configFile)
 
-		newCollector, err := collector.NewCollector(k, configFile)
-		if err != nil {
-			glog.Infof("failed to create collector for container %q, config %q: %v", cont.info.Name, k, err)
-			return err
-		}
-		err = cont.collectorManager.RegisterCollector(newCollector)
-		if err != nil {
-			glog.Infof("failed to register collector for container %q, config %q: %v", cont.info.Name, k, err)
-			return err
+		if strings.HasPrefix(k, "prometheus") || strings.HasPrefix(k, "Prometheus") {
+			newCollector, err := collector.NewPrometheusCollector(k, configFile)
+			if err != nil {
+				glog.Infof("failed to create collector for container %q, config %q: %v", cont.info.Name, k, err)
+				return err
+			}
+			err = cont.collectorManager.RegisterCollector(newCollector)
+			if err != nil {
+				glog.Infof("failed to register collector for container %q, config %q: %v", cont.info.Name, k, err)
+				return err
+			}
+		} else {
+			newCollector, err := collector.NewCollector(k, configFile)
+			if err != nil {
+				glog.Infof("failed to create collector for container %q, config %q: %v", cont.info.Name, k, err)
+				return err
+			}
+			err = cont.collectorManager.RegisterCollector(newCollector)
+			if err != nil {
+				glog.Infof("failed to register collector for container %q, config %q: %v", cont.info.Name, k, err)
+				return err
+			}
 		}
 	}
 	return nil