Add metrics from /metrics/snapshot

This needs to be reworked once we figure out what every metric exactly
means. Right now it just blindly exposes them which isn't best practice.

README.md

@@ -23,5 +23,5 @@ leader and one exporter for each slave with `-slave` pointing to it. In
 a default mesos / DCOS setup, you should be able to run the mesos-exporter
 like this:
 
-- Master: `mesos-exporter -master http://leader.mesos:5050/state.json`
-- Slave: `mesos-exporter -slave http://localhost:5051/monitor/statistics.json`
+- Master: `mesos-exporter -master http://leader.mesos:5050`
+- Slave: `mesos-exporter -slave http://localhost:5051`

main.go

@@ -4,7 +4,6 @@ import (
 	"flag"
 	"log"
 	"net/http"
-	"net/url"
 	"os"
 	"time"
 
@@ -25,22 +24,13 @@ func main() {
 
 	switch {
 	case *masterURL != "":
-		url, err := url.Parse(*masterURL)
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		c := newMasterCollector(url, *timeout)
+		c := newMasterCollector(*masterURL, *timeout)
 		if err := prometheus.Register(c); err != nil {
 			log.Fatal(err)
 		}
 		log.Printf("Exposing master metrics on %s", *addr)
 	case *slaveURL != "":
-		url, err := url.Parse(*slaveURL)
-		if err != nil {
-			log.Fatal(err)
-		}
-		c := newSlaveCollector(url, *timeout)
+		c := newSlaveCollector(*slaveURL, *timeout)
 		if err := prometheus.Register(c); err != nil {
 			log.Fatal(err)
 		}

master.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"log"
 	"net/http"
-	"net/url"
 	"strconv"
 	"time"
 
@@ -63,16 +62,16 @@ type (
 
 	masterCollector struct {
 		*http.Client
-		*url.URL
+		url     string
 		metrics map[prometheus.Collector]func(*state, prometheus.Collector)
 	}
 )
 
-func newMasterCollector(url *url.URL, timeout time.Duration) *masterCollector {
+func newMasterCollector(url string, timeout time.Duration) *masterCollector {
 	labels := []string{"slave"}
 	return &masterCollector{
 		Client: &http.Client{Timeout: timeout},
-		URL:    url,
+		url:    url,
 		metrics: map[prometheus.Collector]func(*state, prometheus.Collector){
 			prometheus.NewGaugeVec(prometheus.GaugeOpts{
 				Help:      "Total slave CPUs (fractional)",
@@ -228,7 +227,7 @@ func newMasterCollector(url *url.URL, timeout time.Duration) *masterCollector {
 }
 
 func (c *masterCollector) Collect(ch chan<- prometheus.Metric) {
-	res, err := c.Do(&http.Request{Method: "GET", URL: c.URL})
+	res, err := c.Get(c.url + "/state.json")
 	if err != nil {
 		log.Print(err)
 		return
@@ -245,6 +244,14 @@ func (c *masterCollector) Collect(ch chan<- prometheus.Metric) {
 		set(&s, c)
 		c.Collect(ch)
 	}
+
+	res, err = c.Get(c.url + "/metrics/snapshot")
+	if err != nil {
+		log.Print(err)
+		return
+	}
+	defer res.Body.Close()
+	snapshotCollect(ch, res.Body)
 }
 
 func (c *masterCollector) Describe(ch chan<- *prometheus.Desc) {

slave.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"log"
 	"net/http"
-	"net/url"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -40,8 +39,7 @@ type (
 
 	slaveCollector struct {
 		*http.Client
-		*url.URL
-		errors  *prometheus.Counter
+		url     string
 		metrics map[*prometheus.Desc]metric
 	}
 
@@ -51,11 +49,12 @@ type (
 	}
 )
 
-func newSlaveCollector(url *url.URL, timeout time.Duration) *slaveCollector {
+func newSlaveCollector(url string, timeout time.Duration) *slaveCollector {
 	labels := []string{"id", "framework_id", "source"}
+
 	return &slaveCollector{
 		Client: &http.Client{Timeout: timeout},
-		URL:    url,
+		url:    url,
 		metrics: map[*prometheus.Desc]metric{
 			// CPU
 			prometheus.NewDesc(
@@ -139,18 +138,16 @@ func newSlaveCollector(url *url.URL, timeout time.Duration) *slaveCollector {
 }
 
 func (c *slaveCollector) Collect(ch chan<- prometheus.Metric) {
-	res, err := http.Get(c.URL.String())
+	res, err := http.Get(c.url + "/monitor/statistics.json")
 	if err != nil {
 		log.Print(err)
-		// c.errors.Inc()
 		return
 	}
 	defer res.Body.Close()
 
 	stats := []executor{}
 	if err := json.NewDecoder(res.Body).Decode(&stats); err != nil {
 		log.Print(err)
-		// c.errors.Inc()
 		return
 	}
 
@@ -159,6 +156,14 @@ func (c *slaveCollector) Collect(ch chan<- prometheus.Metric) {
 			ch <- prometheus.MustNewConstMetric(desc, m.valueType, m.get(exec.Statistics), exec.ID, exec.FrameworkID, exec.Source)
 		}
 	}
+
+	res, err = http.Get(c.url + "/metrics/snapshot")
+	if err != nil {
+		log.Print(err)
+		return
+	}
+	defer res.Body.Close()
+	snapshotCollect(ch, res.Body)
 }
 
 func (c *slaveCollector) Describe(ch chan<- *prometheus.Desc) {