New metrics: XOnBattery, XOffBattery, LastSelfTest, NominalPower (#2)

* Produce metrics for XOnBattery, XOffBattery and LastSelftest.

* Produce metrics for nominal output power.

* Fix cosmetic issues: order of imports and dots at end of sentences.

upscollector.go

@@ -2,6 +2,7 @@ package apcupsdexporter
 
 import (
 	"log"
+	"time"
 
 	"github.com/mdlayher/apcupsd"
 	"github.com/prometheus/client_golang/prometheus"
@@ -27,6 +28,10 @@ type UPSCollector struct {
 	BatteryTimeLeftSeconds              *prometheus.Desc
 	BatteryTimeOnSeconds                *prometheus.Desc
 	BatteryCumulativeTimeOnSecondsTotal *prometheus.Desc
+	LastTransferOnBattery               *prometheus.Desc
+	LastTransferOffBattery              *prometheus.Desc
+	LastSelftest                        *prometheus.Desc
+	NominalPowerWatts                   *prometheus.Desc
 
 	ss StatusSource
 }
@@ -110,6 +115,34 @@ func NewUPSCollector(ss StatusSource) *UPSCollector {
 			nil,
 		),
 
+		LastTransferOnBattery: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "apcupsd_last_transfer_on_battery"),
+			"Time of last transfer to battery since apcupsd startup.",
+			labels,
+			nil,
+		),
+
+		LastTransferOffBattery: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "apcupsd_last_transfer_off_battery"),
+			"Time of last transfer from battery since apcupsd startup.",
+			labels,
+			nil,
+		),
+
+		LastSelftest: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "apcupsd_last_selftest"),
+			"Time of last selftest since apcupsd startup.",
+			labels,
+			nil,
+		),
+
+		NominalPowerWatts: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, "", "apcupsd_nominal_power_watts"),
+			"Nominal power output in watts.",
+			labels,
+			nil,
+		),
+
 		ss: ss,
 	}
 }
@@ -198,9 +231,53 @@ func (c *UPSCollector) collect(ch chan<- prometheus.Metric) (*prometheus.Desc, e
 		labels...,
 	)
 
+	collectTimestamp(
+		ch,
+		c.LastTransferOnBattery,
+		s.XOnBattery,
+		labels...,
+	)
+
+	collectTimestamp(
+		ch,
+		c.LastTransferOffBattery,
+		s.XOffBattery,
+		labels...,
+	)
+
+	collectTimestamp(
+		ch,
+		c.LastSelftest,
+		s.LastSelftest,
+		labels...,
+	)
+
+	ch <- prometheus.MustNewConstMetric(
+		c.NominalPowerWatts,
+		prometheus.GaugeValue,
+		float64(s.NominalPower),
+		labels...,
+	)
+
 	return nil, nil
 }
 
+// collectTimestamp collects timestamp metrics.
+// Timestamps that are zero (time.IsZero() == true) are ignored, as such a timestamp indicates
+// 'information not available', which is best expressed in Prometheus by not having the metric at all.
+func collectTimestamp(ch chan<- prometheus.Metric, desc *prometheus.Desc, time time.Time, labelValues ...string) {
+	if time.IsZero() {
+		return
+	}
+
+	ch <- prometheus.MustNewConstMetric(
+		desc,
+		prometheus.GaugeValue,
+		float64(time.Unix()),
+		labelValues...,
+	)
+}
+
 // Describe sends the descriptors of each metric over to the provided channel.
 // The corresponding metric values are sent separately.
 func (c *UPSCollector) Describe(ch chan<- *prometheus.Desc) {

upscollector_test.go

@@ -42,6 +42,10 @@ func TestUPSCollector(t *testing.T) {
 					LineVoltage:             121.1,
 					LoadPercent:             16.0,
 					NumberTransfers:         1,
+					XOnBattery:              time.Unix(100001, 0),
+					XOffBattery:             time.Unix(100002, 0),
+					LastSelftest:            time.Unix(100003, 0),
+					NominalPower:            50.0,
 				},
 			},
 			matches: []*regexp.Regexp{
@@ -55,6 +59,10 @@ func TestUPSCollector(t *testing.T) {
 				regexp.MustCompile(`apcupsd_line_nominal_volts{hostname="a",model="b",ups_name="c"} 120`),
 				regexp.MustCompile(`apcupsd_line_volts{hostname="a",model="b",ups_name="c"} 121.1`),
 				regexp.MustCompile(`apcupsd_ups_load_percent{hostname="a",model="b",ups_name="c"} 16`),
+				regexp.MustCompile(`apcupsd_last_transfer_on_battery{hostname="a",model="b",ups_name="c"} 100001`),
+				regexp.MustCompile(`apcupsd_last_transfer_off_battery{hostname="a",model="b",ups_name="c"} 100002`),
+				regexp.MustCompile(`apcupsd_last_selftest{hostname="a",model="b",ups_name="c"} 100003`),
+				regexp.MustCompile(`apcupsd_nominal_power_watts{hostname="a",model="b",ups_name="c"} 50`),
 			},
 		},
 	}
@@ -68,7 +76,7 @@ func TestUPSCollector(t *testing.T) {
 
 				t.Run(name, func(t *testing.T) {
 					if !m.Match(out) {
-						t.Fatal("\toutput failed to match regex")
+						t.Fatalf("\toutput failed to match regex (regexp: %v)", m)
 					}
 				})
 			}
@@ -76,6 +84,26 @@ func TestUPSCollector(t *testing.T) {
 	}
 }
 
+// TestZeroTimesAreIgnored tests that times with a zero value (time.IsZero() == true)
+// are not collected.
+func TestZeroTimesAreIgnored(t *testing.T) {
+	ss := &testStatusSource{
+		s: &apcupsd.Status{
+			XOnBattery:  time.Unix(123456, 0),
+			XOffBattery: time.Time{},
+		},
+	}
+	out := testCollector(t, NewUPSCollector(ss))
+	// Test that in general timestamps are collected.
+	if !regexp.MustCompile(`apcupsd_last_transfer_on_battery.* 123456`).Match(out) {
+		t.Error("non-zero timestamp is not reported properly")
+	}
+	// Test that zero timestamps, however, are ignored.
+	if regexp.MustCompile(`apcupsd_last_transfer_off_battery`).Match(out) {
+		t.Error("Zero time is reported")
+	}
+}
+
 func metricName(t *testing.T, metric string) string {
 	ss := strings.Split(metric, " ")
 	if len(ss) != 2 {