Add slowlog_last_id metric.

exporter/redis.go

@@ -200,6 +200,11 @@ func (e *Exporter) initGauges() {
 		Name:      "slowlog_length",
 		Help:      "Total slowlog",
 	}, []string{"addr", "alias"})
+	e.metrics["slowlog_last_id"] = prometheus.NewGaugeVec(prometheus.GaugeOpts{
+		Namespace: e.namespace,
+		Name:      "slowlog_last_id",
+		Help:      "Last id of slowlog",
+	}, []string{"addr", "alias"})
 }
 // splitKeyArgs splits a command-line supplied argument into a slice of dbKeyPairs.
@@ -874,6 +879,20 @@ func (e *Exporter) scrapeRedisHost(scrapes chan<- scrapeResult, addr string, idx
 		e.metricsMtx.RUnlock()
 	}
+	if values, err := redis.Values(c.Do("SLOWLOG", "GET", "1")); err == nil {
+		var slowlogLastId int64 = 0
+
+		if len(values) > 0 {
+			if values, err = redis.Values(values[0], err); err == nil && len(values) > 0 {
+				slowlogLastId = values[0].(int64)
+			}
+		}
+
+		e.metricsMtx.RLock()
+		e.metrics["slowlog_last_id"].WithLabelValues(addr, e.redis.Aliases[idx]).Set(float64(slowlogLastId))
+		e.metricsMtx.RUnlock()
+	}
+
 	log.Debugf("scrapeRedisHost() done")
 	return nil
 }

exporter/redis_test.go

@@ -345,6 +345,7 @@ func TestExporterMetrics(t *testing.T) {
 		"config_maxmemory",  // testing config extraction
 		"config_maxclients", // testing config extraction
 		"slowlog_length",
+		"slowlog_last_id",
 		"start_time_seconds",
 		"uptime_in_seconds",
 	}