feat(prometheus): Support kubernetes metrics

This allows a user to configure the prometheus plugin to poll kuberentes metrics endpoint which expose prometheus metrics

plugins/inputs/prometheus/prometheus.go

@@ -1,49 +1,63 @@
 package prometheus
 
 import (
+	"crypto/tls"
 	"errors"
 	"fmt"
-	"github.com/influxdata/telegraf"
-	"github.com/influxdata/telegraf/plugins/inputs"
-	"github.com/prometheus/common/expfmt"
-	"github.com/prometheus/common/model"
 	"io"
+	"io/ioutil"
+	"net"
 	"net/http"
 	"sync"
 	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/common/model"
 )
 
 type Prometheus struct {
 	Urls []string
+
+	// Use SSL but skip chain & host verification
+	InsecureSkipVerify bool
+	// Bearer Token authorization file path
+	BearerToken string `toml:"bearer_token"`
 }
 
 var sampleConfig = `
   ## An array of urls to scrape metrics from.
   urls = ["http://localhost:9100/metrics"]
+
+	### Use SSL but skip chain & host verification
+	# insecure_skip_verify = false
+	### Use bearer token for authorization
+	# bearer_token = /path/to/bearer/token
 `
 
-func (r *Prometheus) SampleConfig() string {
+func (p *Prometheus) SampleConfig() string {
 	return sampleConfig
 }
 
-func (r *Prometheus) Description() string {
+func (p *Prometheus) Description() string {
 	return "Read metrics from one or many prometheus clients"
 }
 
 var ErrProtocolError = errors.New("prometheus protocol error")
 
 // Reads stats from all configured servers accumulates stats.
 // Returns one of the errors encountered while gather stats (if any).
-func (g *Prometheus) Gather(acc telegraf.Accumulator) error {
+func (p *Prometheus) Gather(acc telegraf.Accumulator) error {
 	var wg sync.WaitGroup
 
 	var outerr error
 
-	for _, serv := range g.Urls {
+	for _, serv := range p.Urls {
 		wg.Add(1)
 		go func(serv string) {
 			defer wg.Done()
-			outerr = g.gatherURL(serv, acc)
+			outerr = p.gatherURL(serv, acc)
 		}(serv)
 	}
 
@@ -52,17 +66,33 @@ func (g *Prometheus) Gather(acc telegraf.Accumulator) error {
 	return outerr
 }
 
-var tr = &http.Transport{
-	ResponseHeaderTimeout: time.Duration(3 * time.Second),
-}
+func (p *Prometheus) gatherURL(url string, acc telegraf.Accumulator) error {
+	var req, err = http.NewRequest("GET", url, nil)
+	req.Header = make(http.Header)
+	var token []byte
+	var resp *http.Response
+
+	var rt http.RoundTripper = &http.Transport{
+		Dial: (&net.Dialer{
+			Timeout:   4 * time.Second,
+			KeepAlive: 30 * time.Second,
+		}).Dial,
+		TLSHandshakeTimeout: 10 * time.Second,
+		TLSClientConfig: &tls.Config{
+			InsecureSkipVerify: true,
+		},
+		ResponseHeaderTimeout: time.Duration(3 * time.Second),
+	}
 
-var client = &http.Client{
-	Transport: tr,
-	Timeout:   time.Duration(4 * time.Second),
-}
+	if p.BearerToken != "" {
+		token, err = ioutil.ReadFile(p.BearerToken)
+		if err != nil {
+			return err
+		}
+		req.Header.Set("Authorization", "Bearer "+string(token))
+	}
 
-func (g *Prometheus) gatherURL(url string, acc telegraf.Accumulator) error {
-	resp, err := client.Get(url)
+	resp, err = rt.RoundTrip(req)
 	if err != nil {
 		return fmt.Errorf("error making HTTP request to %s: %s", url, err)
 	}
@@ -71,9 +101,7 @@ func (g *Prometheus) gatherURL(url string, acc telegraf.Accumulator) error {
 		return fmt.Errorf("%s returned HTTP status %s", url, resp.Status)
 	}
 	format := expfmt.ResponseFormat(resp.Header)
-
 	decoder := expfmt.NewDecoder(resp.Body, format)
-
 	options := &expfmt.DecodeOptions{
 		Timestamp: model.Now(),
 	}
@@ -88,8 +116,7 @@ func (g *Prometheus) gatherURL(url string, acc telegraf.Accumulator) error {
 		if err == io.EOF {
 			break
 		} else if err != nil {
-			return fmt.Errorf("error getting processing samples for %s: %s",
-				url, err)
+			return fmt.Errorf("error getting processing samples for %s: %s", url, err)
 		}
 		for _, sample := range samples {
 			tags := make(map[string]string)
@@ -99,8 +126,11 @@ func (g *Prometheus) gatherURL(url string, acc telegraf.Accumulator) error {
 				}
 				tags[string(key)] = string(value)
 			}
-			acc.Add("prometheus_"+string(sample.Metric[model.MetricNameLabel]),
-				float64(sample.Value), tags)
+			if sample.Value.String() != "NaN" {
+				acc.Add("prometheus_"+string(sample.Metric[model.MetricNameLabel]), float64(sample.Value), tags)
+			} else {
+				acc.Add("prometheus_"+string(sample.Metric[model.MetricNameLabel]), float64(0), tags)
+			}
 		}
 	}
 

plugins/inputs/prometheus/prometheus_test.go

@@ -2,6 +2,7 @@ package prometheus
 
 import (
 	"fmt"
+	"log"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -23,6 +24,7 @@ go_gc_duration_seconds_count 7
 # HELP go_goroutines Number of goroutines that currently exist.
 # TYPE go_goroutines gauge
 go_goroutines 15
+go_gc_metric NaN
 `
 
 func TestPrometheusGeneratesMetrics(t *testing.T) {
@@ -47,6 +49,7 @@ func TestPrometheusGeneratesMetrics(t *testing.T) {
 	}{
 		{"prometheus_go_gc_duration_seconds_count", 7, map[string]string{}},
 		{"prometheus_go_goroutines", 15, map[string]string{}},
+		{"prometheus_go_gc_metric", 0, map[string]string{}},
 	}
 
 	for _, e := range expected {