feat(redis): collect master link status

modules/redis/README.md

@@ -44,6 +44,7 @@ It collects information and statistics about the server executing the following
 ### Replication
 
 - Connected replicas in `replicas`
+- Master link status in `status`
 - Time elapsed since the last interaction with master in `seconds`
 - Time elapsed since the link between master and slave is down in `seconds`
 

modules/redis/charts.go

@@ -19,6 +19,7 @@ const (
 	prioNet
 
 	prioConnectedReplicas
+	prioMasterLinkStatus
 	prioMasterLastIOSinceTime
 	prioMasterLinkDownSinceTime
 
@@ -331,6 +332,18 @@ var (
 			{ID: "connected_slaves", Name: "connected"},
 		},
 	}
+	masterLinkStatusChart = module.Chart{
+		ID:       "master_last_status",
+		Title:    "Master link status",
+		Units:    "status",
+		Fam:      "replication",
+		Ctx:      "redis.master_link_status",
+		Priority: prioMasterLinkStatus,
+		Dims: module.Dims{
+			{ID: "master_link_status_up", Name: "up"},
+			{ID: "master_link_status_down", Name: "down"},
+		},
+	}
 	masterLastIOSinceTimeChart = module.Chart{
 		ID:       "master_last_io_since_time",
 		Title:    "Time elapsed since the last interaction with master",

modules/redis/collect_info.go

@@ -80,6 +80,9 @@ func (r *Redis) collectInfo(mx map[string]int64, info string) {
 			mx[field] = int64(time.Since(time.Unix(v, 0)).Seconds())
 		case field == "aof_enabled" && value == "1":
 			r.addAOFChartsOnce.Do(r.addAOFCharts)
+		case field == "master_link_status":
+			mx["master_link_status_up"] = boolToInt(value == "up")
+			mx["master_link_status_down"] = boolToInt(value == "down")
 		default:
 			collectNumericValue(mx, field, value)
 		}
@@ -227,6 +230,9 @@ func (r *Redis) addAOFCharts() {
 }
 
 func (r *Redis) addReplSlaveCharts() {
+	if err := r.Charts().Add(masterLinkStatusChart.Copy()); err != nil {
+		r.Warningf("error on adding '%s' chart", masterLinkStatusChart.ID)
+	}
 	if err := r.Charts().Add(masterLastIOSinceTimeChart.Copy()); err != nil {
 		r.Warningf("error on adding '%s' chart", masterLastIOSinceTimeChart.ID)
 	}
@@ -243,3 +249,10 @@ func has(m map[string]int64, key string, keys ...string) bool {
 		return ok && has(m, keys[0], keys[1:]...)
 	}
 }
+
+func boolToInt(v bool) int64 {
+	if v {
+		return 1
+	}
+	return 0
+}