re-worked to actually properly work at collecting metrics

collector/collector.go

@@ -1 +1,78 @@
 package collector
+
+import (
+	"sync"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/log"
+)
+
+const namespace = "mikrotik"
+
+var (
+	scrapeDurationDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "scrape", "collector_duration_seconds"),
+		"mikrotik_exporter: duration of a collector scrape",
+		[]string{"device"},
+		nil,
+	)
+	scrapeSuccessDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "scrape", "collector_success"),
+		"mikrotik_exporter: whether a collector succeeded",
+		[]string{"device"},
+		nil,
+	)
+)
+
+type deviceCollector struct {
+	Devices []Device
+}
+
+func NewDeviceCollector(cfg Config) (*deviceCollector, error) {
+	devices := make([]Device, len(cfg.Devices))
+
+	cfg.Logger.Info("setting up collector for devices",
+		"numDevices", len(cfg.Devices),
+	)
+
+	copy(devices, cfg.Devices)
+
+	return &deviceCollector{Devices: devices}, nil
+}
+
+// Describe implements the prometheus.Collector interface.
+func (d deviceCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- scrapeDurationDesc
+	ch <- scrapeSuccessDesc
+}
+
+// Collect implements the prometheus.Collector interface.
+func (d deviceCollector) Collect(ch chan<- prometheus.Metric) {
+	wg := sync.WaitGroup{}
+	wg.Add(len(d.Devices))
+	for _, device := range d.Devices {
+		go func(d Device) {
+			execute(d, ch)
+			wg.Done()
+		}(device)
+	}
+	wg.Wait()
+}
+
+func execute(d Device, ch chan<- prometheus.Metric) {
+	begin := time.Now()
+	err := d.Update(ch)
+	duration := time.Since(begin)
+	var success float64
+
+	if err != nil {
+		log.Errorf("ERROR: %s collector failed after %fs: %s", d.name, duration.Seconds(), err)
+		success = 0
+	} else {
+		log.Debugf("OK: %s collector succeeded after %fs.", d.name, duration.Seconds())
+		success = 1
+	}
+	ch <- prometheus.MustNewConstMetric(scrapeDurationDesc, prometheus.GaugeValue, duration.Seconds(), d.name)
+	ch <- prometheus.MustNewConstMetric(scrapeSuccessDesc, prometheus.GaugeValue, success, d.name)
+}