Implement logic

Signed-off-by: Marcus Noble <github@marcusnoble.co.uk>

main.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var (
+	isOnline int = 0
+
+	interval int
+	timeout  int
+	port     int
+	endpoint string
+)
+
+func init() {
+	flag.IntVar(&interval, "interval", 15, "Duration, in seconds, between checks")
+	flag.IntVar(&timeout, "timeout", 5000, "Timeout in ms")
+	flag.IntVar(&port, "port", 9091, "The port to listen on")
+	flag.StringVar(&endpoint, "endpoint", "https://1.1.1.1", "The endpoint to test against")
+	flag.Parse()
+}
+
+func main() {
+	go (func() {
+		for {
+			checkOnline()
+			time.Sleep(time.Minute * time.Duration(interval))
+		}
+	})()
+
+	collector := newSpeedCollector()
+	prometheus.MustRegister(collector)
+	http.Handle("/metrics", promhttp.Handler())
+	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", port), nil))
+}
+
+func checkOnline() {
+	client := http.Client{
+		Timeout: time.Duration(timeout) * time.Millisecond,
+	}
+	_, err := client.Get(endpoint)
+	if err != nil {
+		isOnline = 0
+	} else {
+		isOnline = 1
+	}
+}
+
+type speedCollector struct {
+	onlineMetric *prometheus.Desc
+}
+
+func newSpeedCollector() *speedCollector {
+	return &speedCollector{
+		onlineMetric: prometheus.NewDesc("is_online",
+			"Is online",
+			nil, nil,
+		),
+	}
+}
+
+func (collector *speedCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- collector.onlineMetric
+}
+
+func (collector *speedCollector) Collect(ch chan<- prometheus.Metric) {
+	ch <- prometheus.MustNewConstMetric(collector.onlineMetric, prometheus.CounterValue, float64(isOnline))
+}