Add a NATS monitoring input plugin

Signed-off-by: Levente Kurusa <levex@linux.com>

Godeps

@@ -33,6 +33,7 @@ github.com/kballard/go-shellquote d8ec1a69a250a17bb0e419c386eac1f3711dc142
 github.com/matttproud/golang_protobuf_extensions c12348ce28de40eed0136aa2b644d0ee0650e56c
 github.com/miekg/dns 99f84ae56e75126dd77e5de4fae2ea034a468ca1
 github.com/naoina/go-stringutil 6b638e95a32d0c1131db0e7fe83775cbea4a0d0b
+github.com/nats-io/gnatsd 393bbb7c031433e68707c8810fda0bfcfbe6ab9b
 github.com/nats-io/go-nats ea9585611a4ab58a205b9b125ebd74c389a6b898
 github.com/nats-io/nats ea9585611a4ab58a205b9b125ebd74c389a6b898
 github.com/nats-io/nuid 289cccf02c178dc782430d534e3c1f5b72af807f

plugins/inputs/all/all.go

@@ -51,6 +51,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/inputs/mqtt_consumer"
 	_ "github.com/influxdata/telegraf/plugins/inputs/mysql"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nats_consumer"
+	_ "github.com/influxdata/telegraf/plugins/inputs/nats"
 	_ "github.com/influxdata/telegraf/plugins/inputs/net_response"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nginx"
 	_ "github.com/influxdata/telegraf/plugins/inputs/nsq"

plugins/inputs/nats/README.md

@@ -0,0 +1,12 @@
+# NATS Monitoring Input Plugin
+
+The [NATS](http://www.nats.io/about/) monitoring plugin reads from
+specified NATS instance and submits metrics to InfluxDB. 
+
+## Configuration
+
+```toml
+[[inputs.nats_top]]
+  ## The address of the monitoring end-point of the NATS server
+  server = "http://localhost:8222"
+```

plugins/inputs/nats/nats.go

@@ -0,0 +1,79 @@
+package nats
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	"encoding/json"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/plugins/inputs"
+
+	gnatsd "github.com/nats-io/gnatsd/server"
+)
+
+type Nats struct {
+	Server string
+}
+
+var sampleConfig = `
+  ## The address of the monitoring end-point of the NATS server
+  server = "http://localhost:1337"
+`
+
+func (n *Nats) SampleConfig() string {
+	return sampleConfig
+}
+
+func (n *Nats) Description() string {
+	return "Provides metrics about the state of a NATS server"
+}
+
+func (n *Nats) Gather(acc telegraf.Accumulator) error {
+	theServer := fmt.Sprintf("%s/varz", n.Server)
+
+	/* download the page we are intereted in */
+	resp, err := http.Get(theServer)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	bytes, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	var stats = new(gnatsd.Varz)
+
+	err = json.Unmarshal([]byte(bytes), &stats)
+	if err != nil {
+		return err
+	}
+
+	acc.AddFields("nats",
+		map[string]interface{}{
+			"in_msgs":           stats.InMsgs,
+			"out_msgs":          stats.OutMsgs,
+			"uptime":            time.Since(stats.Start).Seconds(),
+			"connections":       stats.Connections,
+			"total_connections": stats.TotalConnections,
+			"in_bytes":          stats.InBytes,
+			"cpu_usage":         stats.CPU,
+			"out_bytes":         stats.OutBytes,
+			"mem":               stats.Mem,
+			"subscriptions":     stats.Subscriptions,
+		}, nil, time.Now())
+
+	return nil
+}
+
+func init() {
+	inputs.Add("nats", func() telegraf.Input {
+		return &Nats{
+			Server: "http://localhost:8222",
+		}
+	})
+}

plugins/inputs/nats/nats_test.go

@@ -0,0 +1,114 @@
+package nats
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/influxdata/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var sampleVarz = `
+{
+  "server_id": "n2afhLHLl64Gcaj7S7jaNa",
+  "version": "1.0.0",
+  "go": "go1.8",
+  "host": "0.0.0.0",
+  "auth_required": false,
+  "ssl_required": false,
+  "tls_required": false,
+  "tls_verify": false,
+  "addr": "0.0.0.0",
+  "max_connections": 65536,
+  "ping_interval": 120000000000,
+  "ping_max": 2,
+  "http_host": "0.0.0.0",
+  "http_port": 1337,
+  "https_port": 0,
+  "auth_timeout": 1,
+  "max_control_line": 1024,
+  "cluster": {
+    "addr": "0.0.0.0",
+    "cluster_port": 0,
+    "auth_timeout": 1
+  },
+  "tls_timeout": 0.5,
+  "port": 4222,
+  "max_payload": 1048576,
+  "start": "1861-04-12T10:15:26.841483489-05:00",
+  "now": "2011-10-05T15:24:23.722084098-07:00",
+  "uptime": "150y5md237h8m57s",
+  "mem": 15581184,
+  "cores": 48,
+  "cpu": 9,
+  "connections": 2,
+  "total_connections": 109,
+  "routes": 0,
+  "remotes": 0,
+  "in_msgs": 74148556,
+  "out_msgs": 68863261,
+  "in_bytes": 946267004717,
+  "out_bytes": 948110960598,
+  "slow_consumers": 0,
+  "subscriptions": 1,
+  "http_req_stats": {
+    "/": 1,
+    "/connz": 100847,
+    "/routez": 0,
+    "/subsz": 1,
+    "/varz": 205785
+  },
+  "config_load_time": "2017-07-24T10:15:26.841483489-05:00"
+}
+`
+
+func TestMetricsCorrect(t *testing.T) {
+	var acc testutil.Accumulator
+
+	srv := newTestNatsServer()
+	defer srv.Close()
+
+	n := &Nats{Server: srv.URL}
+	err := n.Gather(&acc)
+	require.NoError(t, err)
+
+	/*
+			 * we get the measurement, and override it, this is neccessary
+		         * because we can't "equal" the uptime value reliably, as it is
+			 * calculated via Time.Now() and the Start value in Varz
+	*/
+	s, f := acc.Get("nats")
+	assert.Equal(t, true, f, "nats measurement must be found")
+
+	fields := make(map[string]interface{})
+	fields["uptime"] = s.Fields["uptime"]
+	fields["in_msgs"] = int64(74148556)
+	fields["out_msgs"] = int64(68863261)
+	fields["connections"] = int(2)
+	fields["total_connections"] = uint64(109)
+	fields["in_bytes"] = int64(946267004717)
+	fields["out_bytes"] = int64(948110960598)
+	fields["cpu_usage"] = float64(9)
+	fields["mem"] = int64(15581184)
+	fields["subscriptions"] = uint32(1)
+
+	acc.AssertContainsFields(t, "nats", fields)
+}
+
+func newTestNatsServer() *httptest.Server {
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var rsp string
+
+		switch r.URL.Path {
+		case "/varz":
+			rsp = sampleVarz
+		default:
+			panic("Cannot handle request")
+		}
+
+		fmt.Fprintln(w, rsp)
+	}))
+}