initial commit

exporter.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net/http"
+	"sync"
+
+	"github.com/martinlindhe/wmi_exporter/collectors"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// WmiExporter wraps all the WMI collectors and provides a single global
+// exporter to extracts metrics out of. It also ensures that the collection
+// is done in a thread-safe manner, the necessary requirement stated by
+// prometheus. It also implements a prometheus.Collector interface in order
+// to register it correctly.
+type WmiExporter struct {
+	mu         sync.Mutex
+	collectors []prometheus.Collector
+}
+
+// Verify that the WmiExporter implements the prometheus.Collector interface.
+var _ prometheus.Collector = &WmiExporter{}
+
+// NewWmiExporter creates an instance to WmiExporter and returns a reference
+// to it. We can choose to enable a collector to extract stats out of by adding
+// it to the list of collectors.
+func NewWmiExporter() *WmiExporter {
+	return &WmiExporter{
+		collectors: []prometheus.Collector{
+			collectors.NewOSCollector(),
+		},
+	}
+}
+
+// Describe sends all the descriptors of the collectors included to
+// the provided channel.
+func (c *WmiExporter) Describe(ch chan<- *prometheus.Desc) {
+	for _, cc := range c.collectors {
+		cc.Describe(ch)
+	}
+}
+
+// Collect sends the collected metrics from each of the collectors to
+// prometheus. Collect could be called several times concurrently
+// and thus its run is protected by a single mutex.
+func (c *WmiExporter) Collect(ch chan<- prometheus.Metric) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	for _, cc := range c.collectors {
+		cc.Collect(ch)
+	}
+}
+
+func main() {
+	var (
+		addr        = flag.String("telemetry.addr", ":9129", "host:port for WMI exporter")
+		metricsPath = flag.String("telemetry.path", "/metrics", "URL path for surfacing collected metrics")
+	)
+	flag.Parse()
+
+	prometheus.MustRegister(NewWmiExporter())
+
+	http.Handle(*metricsPath, prometheus.Handler())
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		http.Redirect(w, r, *metricsPath, http.StatusMovedPermanently)
+	})
+
+	log.Printf("Starting WMI exporter on %q", *addr)
+	if err := http.ListenAndServe(*addr, nil); err != nil {
+		log.Fatalf("cannot start WMI exporter: %s", err)
+	}
+}