x509 certs authentication now supported for Prometheus input plugin (#1396)

CHANGELOG.md

@@ -56,6 +56,7 @@ should now look like:
 - [#1335](https://github.com/influxdata/telegraf/issues/1335): Fix overall ping timeout to be calculated based on per-ping timeout.
 - [#1374](https://github.com/influxdata/telegraf/pull/1374): Change "default" retention policy to "".
 - [#1377](https://github.com/influxdata/telegraf/issues/1377): Graphite output mangling '%' character.
+- [#1396](https://github.com/influxdata/telegraf/pull/1396): Prometheus input plugin now supports x509 certs authentication
 
 ## v1.0 beta 1 [2016-06-07]
 

plugins/inputs/prometheus/README.md

@@ -30,6 +30,26 @@ to filter and some tags
     kubeservice = "kube-apiserver"
 ```
 
+```toml
+# Authorize with a bearer token skipping cert verification
+[[inputs.prometheus]]
+  # An array of urls to scrape metrics from.
+  urls = ["http://my-kube-apiserver:8080/metrics"]
+  bearer_token = '/path/to/bearer/token'
+  insecure_skip_verify = true
+```
+
+```toml
+# Authorize using x509 certs
+[[inputs.prometheus]]
+  # An array of urls to scrape metrics from.
+  urls = ["https://my-kube-apiserver:8080/metrics"]
+
+  ssl_ca = '/path/to/cafile'
+  ssl_cert = '/path/to/certfile'
+  ssl_key = '/path/to/keyfile'
+```
+
 ### Measurements & Fields & Tags:
 
 Measurements and fields could be any thing.

plugins/inputs/prometheus/prometheus.go

@@ -1,10 +1,10 @@
 package prometheus
 
 import (
-	"crypto/tls"
 	"errors"
 	"fmt"
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/plugins/inputs"
 	"io/ioutil"
 	"net"
@@ -16,20 +16,32 @@ import (
 type Prometheus struct {
 	Urls []string
 
-	// Use SSL but skip chain & host verification
-	InsecureSkipVerify bool
 	// Bearer Token authorization file path
 	BearerToken string `toml:"bearer_token"`
+
+	// Path to CA file
+	SSLCA string `toml:"ssl_ca"`
+	// Path to host cert file
+	SSLCert string `toml:"ssl_cert"`
+	// Path to cert key file
+	SSLKey string `toml:"ssl_key"`
+	// Use SSL but skip chain & host verification
+	InsecureSkipVerify bool
 }
 
 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
+
+  ## Optional SSL Config
+  # ssl_ca = /path/to/cafile
+  # ssl_cert = /path/to/certfile
+  # ssl_key = /path/to/keyfile
+  ## Use SSL but skip chain & host verification
+  # insecure_skip_verify = false
 `
 
 func (p *Prometheus) SampleConfig() string {
@@ -78,15 +90,19 @@ func (p *Prometheus) gatherURL(url string, acc telegraf.Accumulator) error {
 	var token []byte
 	var resp *http.Response
 
+	tlsCfg, err := internal.GetTLSConfig(
+		p.SSLCert, p.SSLKey, p.SSLCA, p.InsecureSkipVerify)
+	if err != nil {
+		return err
+	}
+
 	var rt http.RoundTripper = &http.Transport{
 		Dial: (&net.Dialer{
 			Timeout:   5 * time.Second,
 			KeepAlive: 30 * time.Second,
 		}).Dial,
 		TLSHandshakeTimeout:   5 * time.Second,
-		TLSClientConfig: &tls.Config{
+		TLSClientConfig:       tlsCfg,
-			InsecureSkipVerify: p.InsecureSkipVerify,
-		},
 		ResponseHeaderTimeout: time.Duration(3 * time.Second),
 		DisableKeepAlives:     true,
 	}