add elasticsearch_up metric

conf/input.elasticsearch/elasticsearch.toml

@@ -3,7 +3,7 @@
 
 ############################################################################
 # !!! uncomment [[instances]] to enable this plugin
-# [[instances]]
+[[instances]]
 # # interval = global.interval * interval_times
 # interval_times = 1
 
@@ -11,7 +11,8 @@
 # labels = { cluster="cloud-n9e-es" }
 
 ## specify a list of one or more Elasticsearch servers
-servers = ["http://localhost:9200"]
+# servers = ["http://localhost:9200"]
+servers = []
 
 ## Timeout for HTTP requests to the elastic search server(s)
 http_timeout = "5s"
@@ -47,8 +48,8 @@ indices_level = "shards"
 # node_stats = ["jvm", "http"]
 
 ## HTTP Basic Authentication username and password.
-# username = ""
-# password = ""
+username = "elastic"
+password = "password"
 
 ## Optional TLS Config
 # use_tls = false

conf/traces.yaml

@@ -5,7 +5,7 @@
 # For more details, see the OpenTelemetry official docs:
 #     https://opentelemetry.io/docs/collector/configuration/
 traces:
-  enable: true
+  enable: false
   extensions:
     health_check:
     pprof:

inputs/elasticsearch/elasticsearch.go

@@ -2,6 +2,7 @@ package elasticsearch
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -111,7 +112,9 @@ func (r *Elasticsearch) Init() error {
 
 	for i := 0; i < len(r.Instances); i++ {
 		if err := r.Instances[i].Init(); err != nil {
-			return err
+			if !errors.Is(err, types.ErrInstancesEmpty) {
+				return err
+			}
 		}
 	}
 
@@ -229,6 +232,7 @@ func (ins *Instance) gatherOnce(slist *list.SafeList) {
 
 				// Gather node ID
 				if info.nodeID, err = ins.gatherNodeID(s + "/_nodes/_local/name"); err != nil {
+					slist.PushFront(inputs.NewSample("up", 0, ins.Labels))
 					log.Println("E! failed to gather node id:", err)
 					return
 				}
@@ -236,10 +240,12 @@ func (ins *Instance) gatherOnce(slist *list.SafeList) {
 				// get cat/master information here so NodeStats can determine
 				// whether this node is the Master
 				if info.masterID, err = ins.getCatMaster(s + "/_cat/master"); err != nil {
+					slist.PushFront(inputs.NewSample("up", 0, ins.Labels))
 					log.Println("E! failed to get cat master:", err)
 					return
 				}
 
+				slist.PushFront(inputs.NewSample("up", 1, ins.Labels))
 				ins.serverInfoMutex.Lock()
 				ins.serverInfo[s] = info
 				ins.serverInfoMutex.Unlock()