add support for exporter basic auth

README.md

@@ -59,17 +59,21 @@ Help:
 
 ```
 $ sensu-prometheus-collector -h
-Usage of ./sensu-prometheus-collector:
+Usage of sensu-prometheus-collector:
+  -exporter-password string
+    	Prometheus exporter basic auth password
   -exporter-url string
-        Prometheus exporter URL to pull metrics from.
+    	Prometheus exporter URL to pull metrics from.
+  -exporter-user string
+    	Prometheus exporter basic auth user
   -metric-prefix string
-        Metric name prefix, only supported by line protocol output formats.
+    	Metric name prefix, only supported by line protocol output formats.
   -output-format string
-        The check output format to use for metrics {influx|graphite|json}. (default "influx")
+    	The check output format to use for metrics {influx|graphite|json}. (default "influx")
   -prom-query string
-        Prometheus API query string. (default "up")
+    	Prometheus API query string. (default "up")
   -prom-url string
-        Prometheus API URL. (default "http://localhost:9090")
+    	Prometheus API URL. (default "http://localhost:9090")
 ```
 
 Application instrumentation:
@@ -82,12 +86,14 @@ go_memstats_mspan_sys_bytes value=32768 1506991233
 ```
 
 ```
-$ sensu-prometheus-collector -exporter-url http://localhost:8080/metrics -output-format graphite -metric-prefix foo.bar.
+$ sensu-prometheus-collector -exporter-url http://localhost:8080/metrics -exporter-user admin -exporter-password secretpassword -output-format graphite -metric-prefix foo.bar.
 foo.bar.go_memstats_stack_inuse_bytes 294912 1506991405
 foo.bar.go_memstats_mallocs_total 6375 1506991405
 ...
 ```
 
+Exporter basic auth credentials can also be set via environment vars `EXPORTER_USER` and `EXPORTER_PASSWORD`.
+
 Prometheus query API:
 
 ```

sensu-prometheus-collector.go

@@ -11,11 +11,16 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/kelseyhightower/envconfig"
 	"github.com/prometheus/client_golang/api/prometheus"
 	"github.com/prometheus/common/expfmt"
 	"github.com/prometheus/common/model"
 )
 
+const (
+	exporterAuthID = "exporter"
+)
+
 type Tag struct {
 	Name  model.LabelName
 	Value model.LabelValue
@@ -26,6 +31,11 @@ type Metric struct {
 	Value float64
 }
 
+type exporterAuth struct {
+	User     string `envconfig:"user" default:""`
+	Password string `envconfig:"password" default:""`
+}
+
 func CreateJSONMetrics(samples model.Vector) string {
 	metrics := []Metric{}
 
@@ -138,17 +148,23 @@ func QueryPrometheus(promURL string, queryString string) (model.Vector, error) {
 	return nil, errors.New("unexpected response type")
 }
 
-func QueryExporter(exporterURL string) (model.Vector, error) {
-	expResponse, err := http.Get(exporterURL)
-	defer expResponse.Body.Close()
-
+func QueryExporter(exporterURL string, auth exporterAuth) (model.Vector, error) {
+	client := &http.Client{}
+	req, err := http.NewRequest("GET", exporterURL, nil)
 	if err != nil {
 		return nil, err
 	}
 
+	req.SetBasicAuth(auth.User, auth.Password)
+
+	expResponse, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
 	if expResponse.StatusCode != http.StatusOK {
-		return nil, errors.New("exporter returned non OK HTTP response status")
+		return nil, errors.New("exporter returned non OK HTTP response status: " + expResponse.Status)
 	}
+	defer expResponse.Body.Close()
 
 	var parser expfmt.TextParser
 
@@ -172,32 +188,42 @@ func QueryExporter(exporterURL string) (model.Vector, error) {
 	return samples, nil
 }
 
+func setExporterAuth(user string, password string) (auth exporterAuth) {
+	envconfig.Process(exporterAuthID, &auth)
+	if user != "" && password != "" {
+		auth = exporterAuth{User: user, Password: password}
+	}
+	return
+}
+
 func main() {
 	exporterURL := flag.String("exporter-url", "", "Prometheus exporter URL to pull metrics from.")
+	exporterUser := flag.String("exporter-user", "", "Prometheus exporter basic auth user")
+	exporterPassword := flag.String("exporter-password", "", "Prometheus exporter basic auth password")
 	promURL := flag.String("prom-url", "http://localhost:9090", "Prometheus API URL.")
 	queryString := flag.String("prom-query", "up", "Prometheus API query string.")
 	outputFormat := flag.String("output-format", "influx", "The check output format to use for metrics {influx|graphite|json}.")
 	metricPrefix := flag.String("metric-prefix", "", "Metric name prefix, only supported by line protocol output formats.")
 	flag.Parse()
 
-	samples := model.Vector{}
+	var samples model.Vector
 	var err error
 
 	if *exporterURL != "" {
-		samples, err = QueryExporter(*exporterURL)
+		samples, err = QueryExporter(*exporterURL, setExporterAuth(*exporterUser, *exporterPassword))
 	} else {
 		samples, err = QueryPrometheus(*promURL, *queryString)
 	}
 
 	if err != nil {
-		fmt.Errorf("%v", err)
+		_ = fmt.Errorf("%v", err)
 		os.Exit(2)
 	}
 
 	err = OutputMetrics(samples, *outputFormat, *metricPrefix)
 
 	if err != nil {
-		fmt.Errorf("%v", err)
+		_ = fmt.Errorf("%v", err)
 		os.Exit(2)
 	}
 }

sensu-prometheus-collector_test.go

@@ -17,7 +17,7 @@ func TestQueryExporter(t *testing.T) {
 
 	time.Sleep(2 * time.Second)
 
-	samples, err := QueryExporter("http://localhost:7777/metrics")
+	samples, err := QueryExporter("http://localhost:7777/metrics", exporterAuth{User: "", Password: ""})
 
 	assert.NoError(t, err)
 	assert.NotNil(t, samples)