influxdb output time.Duration fixup

The default is 0 so we hit a division by 0 error and crash. This checks
ensure we will not crash and `log` and continue to let telegraf run

Also we set default allow pending message number to 10000

CHANGELOG.md

@@ -1,4 +1,44 @@
 ## v1.0 [unreleased]
+## v1.1 [unreleased]
+
+### Release Notes
+
+### Features
+
+- [#1694](https://github.com/influxdata/telegraf/pull/1694): Adding Gauge and Counter metric types.
+- [#1606](https://github.com/influxdata/telegraf/pull/1606): Remove carraige returns from exec plugin output on Windows
+- [#1674](https://github.com/influxdata/telegraf/issues/1674): elasticsearch input: configurable timeout.
+- [#1607](https://github.com/influxdata/telegraf/pull/1607): Massage metric names in Instrumental output plugin
+- [#1572](https://github.com/influxdata/telegraf/pull/1572): mesos improvements.
+- [#1513](https://github.com/influxdata/telegraf/issues/1513): Add Ceph Cluster Performance Statistics
+- [#1650](https://github.com/influxdata/telegraf/issues/1650): Ability to configure response_timeout in httpjson input.
+- [#1685](https://github.com/influxdata/telegraf/issues/1685): Add additional redis metrics.
+- [#1539](https://github.com/influxdata/telegraf/pull/1539): Added capability to send metrics through Http API for OpenTSDB.
+- [#1471](https://github.com/influxdata/telegraf/pull/1471): iptables input plugin.
+- [#1542](https://github.com/influxdata/telegraf/pull/1542): Add filestack webhook plugin.
+- [#1599](https://github.com/influxdata/telegraf/pull/1599): Add server hostname for each docker measurements.
+- [#1697](https://github.com/influxdata/telegraf/pull/1697): Add NATS output plugin.
+- [#1407](https://github.com/influxdata/telegraf/pull/1407): HTTP service listener input plugin.
+- [#1699](https://github.com/influxdata/telegraf/pull/1699): Add database blacklist option for Postgresql
+
+### Bugfixes
+
+- [#1628](https://github.com/influxdata/telegraf/issues/1628): Fix mongodb input panic on version 2.2.
+- [#1738](https://github.com/influxdata/telegraf/issues/1738): Fix unmarshal of influxdb metrics with null tags
+- [#1733](https://github.com/influxdata/telegraf/issues/1733): Fix statsd scientific notation parsing
+- [#1716](https://github.com/influxdata/telegraf/issues/1716): Sensors plugin strconv.ParseFloat: parsing "": invalid syntax
+- [#1530](https://github.com/influxdata/telegraf/issues/1530): Fix prometheus_client reload panic
+- [#1764](https://github.com/influxdata/telegraf/issues/1764): Fix kafka consumer panic when nil error is returned down errs channel.
+
+## v1.0.1 [unreleased]
+
+### Bugfixes
+
+- [#1775](https://github.com/influxdata/telegraf/issues/1775): Prometheus output: Fix bug with multi-batch writes.
+- [#1738](https://github.com/influxdata/telegraf/issues/1738): Fix unmarshal of influxdb metrics with null tags.
+- [#1773](https://github.com/influxdata/telegraf/issues/1773): Add configurable timeout to influxdb input plugin.
+
+## v1.0 [2016-09-08]
 
 ### Release Notes
 

plugins/inputs/influxdb/influxdb.go

@@ -10,11 +10,16 @@ import (
 	"time"
 
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal"
 	"github.com/influxdata/telegraf/plugins/inputs"
 )
 
 type InfluxDB struct {
 	URLs []string `toml:"urls"`
+
+	Timeout internal.Duration
+
+	client *http.Client
 }
 
 func (*InfluxDB) Description() string {
@@ -32,6 +37,9 @@ func (*InfluxDB) SampleConfig() string {
   urls = [
     "http://localhost:8086/debug/vars"
   ]
+
+  ## http request & header timeout
+  timeout = "5s"
 `
 }
 
@@ -39,6 +47,16 @@ func (i *InfluxDB) Gather(acc telegraf.Accumulator) error {
 	if len(i.URLs) == 0 {
 		i.URLs = []string{"http://localhost:8086/debug/vars"}
 	}
+
+	if i.client == nil {
+		i.client = &http.Client{
+			Transport: &http.Transport{
+				ResponseHeaderTimeout: i.Timeout.Duration,
+			},
+			Timeout: i.Timeout.Duration,
+		}
+	}
+
 	errorChannel := make(chan error, len(i.URLs))
 
 	var wg sync.WaitGroup
@@ -104,15 +122,6 @@ type memstats struct {
 	GCCPUFraction float64 `json:"GCCPUFraction"`
 }
 
-var tr = &http.Transport{
-	ResponseHeaderTimeout: time.Duration(3 * time.Second),
-}
-
-var client = &http.Client{
-	Transport: tr,
-	Timeout:   time.Duration(4 * time.Second),
-}
-
 // Gathers data from a particular URL
 // Parameters:
 //     acc    : The telegraf Accumulator to use
@@ -127,7 +136,7 @@ func (i *InfluxDB) gatherURL(
 	shardCounter := 0
 	now := time.Now()
 
-	resp, err := client.Get(url)
+	resp, err := i.client.Get(url)
 	if err != nil {
 		return err
 	}
@@ -210,9 +219,13 @@ func (i *InfluxDB) gatherURL(
 			continue
 		}
 
+		if p.Tags == nil {
+			p.Tags = make(map[string]string)
+		}
+
 		// If the object was a point, but was not fully initialized,
 		// ignore it and move on.
-		if p.Name == "" || p.Tags == nil || p.Values == nil || len(p.Values) == 0 {
+		if p.Name == "" || p.Values == nil || len(p.Values) == 0 {
 			continue
 		}
 
@@ -244,6 +257,8 @@ func (i *InfluxDB) gatherURL(
 
 func init() {
 	inputs.Add("influxdb", func() telegraf.Input {
-		return &InfluxDB{}
+		return &InfluxDB{
+			Timeout: internal.Duration{Duration: time.Second * 5},
+		}
 	})
 }

plugins/inputs/influxdb/influxdb_test.go

@@ -116,6 +116,31 @@ func TestInfluxDB(t *testing.T) {
 		}, map[string]string{})
 }
 
+func TestInfluxDB2(t *testing.T) {
+	fakeInfluxServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/endpoint" {
+			_, _ = w.Write([]byte(influxReturn2))
+		} else {
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+	defer fakeInfluxServer.Close()
+
+	plugin := &influxdb.InfluxDB{
+		URLs: []string{fakeInfluxServer.URL + "/endpoint"},
+	}
+
+	var acc testutil.Accumulator
+	require.NoError(t, plugin.Gather(&acc))
+
+	require.Len(t, acc.Metrics, 34)
+
+	acc.AssertContainsTaggedFields(t, "influxdb",
+		map[string]interface{}{
+			"n_shards": 1,
+		}, map[string]string{})
+}
+
 func TestErrorHandling(t *testing.T) {
 	badServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path == "/endpoint" {
@@ -241,3 +266,49 @@ const influxReturn = `
 "tsm1_wal:/Users/csparr/.influxdb/wal/udp/default/1": {"name": "tsm1_wal", "tags": {"database": "udp", "path": "/Users/csparr/.influxdb/wal/udp/default/1", "retentionPolicy": "default"}, "values": {"currentSegmentDiskBytes": 193728, "oldSegmentsDiskBytes": 1008330}},
 "write": {"name": "write", "tags": {}, "values": {"pointReq": 3613, "pointReqLocal": 3613, "req": 110, "subWriteOk": 110, "writeOk": 110}}
 }`
+
+// InfluxDB 1.0+ with tags: null instead of tags: {}.
+const influxReturn2 = `
+{
+"cluster": {"name": "cluster", "tags": null, "values": {}},
+"cmdline": ["influxd"],
+"cq": {"name": "cq", "tags": null, "values": {}},
+"database:_internal": {"name": "database", "tags": {"database": "_internal"}, "values": {"numMeasurements": 8, "numSeries": 12}},
+"database:udp": {"name": "database", "tags": {"database": "udp"}, "values": {"numMeasurements": 14, "numSeries": 38}},
+"hh:/Users/csparr/.influxdb/hh": {"name": "hh", "tags": {"path": "/Users/csparr/.influxdb/hh"}, "values": {}},
+"httpd::8086": {"name": "httpd", "tags": {"bind": ":8086"}, "values": {"req": 7, "reqActive": 1, "reqDurationNs": 4488799}},
+"measurement:cpu_idle.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "cpu_idle"}, "values": {"numSeries": 1}},
+"measurement:cpu_usage.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "cpu_usage"}, "values": {"numSeries": 1}},
+"measurement:database._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "database"}, "values": {"numSeries": 2}},
+"measurement:database.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "database"}, "values": {"numSeries": 2}},
+"measurement:httpd.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "httpd"}, "values": {"numSeries": 1}},
+"measurement:measurement.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "measurement"}, "values": {"numSeries": 22}},
+"measurement:mem.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "mem"}, "values": {"numSeries": 1}},
+"measurement:net.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "net"}, "values": {"numSeries": 1}},
+"measurement:runtime._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "runtime"}, "values": {"numSeries": 1}},
+"measurement:runtime.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "runtime"}, "values": {"numSeries": 1}},
+"measurement:shard._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "shard"}, "values": {"numSeries": 2}},
+"measurement:shard.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "shard"}, "values": {"numSeries": 1}},
+"measurement:subscriber._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "subscriber"}, "values": {"numSeries": 1}},
+"measurement:subscriber.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "subscriber"}, "values": {"numSeries": 1}},
+"measurement:swap_used.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "swap_used"}, "values": {"numSeries": 1}},
+"measurement:tsm1_cache._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "tsm1_cache"}, "values": {"numSeries": 2}},
+"measurement:tsm1_cache.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "tsm1_cache"}, "values": {"numSeries": 2}},
+"measurement:tsm1_wal._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "tsm1_wal"}, "values": {"numSeries": 2}},
+"measurement:tsm1_wal.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "tsm1_wal"}, "values": {"numSeries": 2}},
+"measurement:udp._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "udp"}, "values": {"numSeries": 1}},
+"measurement:write._internal": {"name": "measurement", "tags": {"database": "_internal", "measurement": "write"}, "values": {"numSeries": 1}},
+"measurement:write.udp": {"name": "measurement", "tags": {"database": "udp", "measurement": "write"}, "values": {"numSeries": 1}},
+"memstats": {"Alloc":17034016,"TotalAlloc":201739016,"Sys":38537464,"Lookups":77,"Mallocs":570251,"Frees":381008,"HeapAlloc":17034016,"HeapSys":33849344,"HeapIdle":15802368,"HeapInuse":18046976,"HeapReleased":3473408,"HeapObjects":189243,"StackInuse":753664,"StackSys":753664,"MSpanInuse":97440,"MSpanSys":114688,"MCacheInuse":4800,"MCacheSys":16384,"BuckHashSys":1461583,"GCSys":1112064,"OtherSys":1229737,"NextGC":20843042,"LastGC":1460434886475114239,"PauseTotalNs":5132914,"PauseNs":[195052,117751,139370,156933,263089,165249,713747,103904,122015,294408,213753,170864,175845,114221,121563,122409,113098,162219,229257,126726,250774,254235,117206,293588,144279,124306,127053,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"PauseEnd":[1460433856394860455,1460433856398162739,1460433856405888337,1460433856411784017,1460433856417924684,1460433856428385687,1460433856443782908,1460433856456522851,1460433857392743223,1460433866484394564,1460433866494076235,1460433896472438632,1460433957839825106,1460433976473440328,1460434016473413006,1460434096471892794,1460434126470792929,1460434246480428250,1460434366554468369,1460434396471249528,1460434456471205885,1460434476479487292,1460434536471435965,1460434616469784776,1460434736482078216,1460434856544251733,1460434886475114239,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],"NumGC":27,"GCCPUFraction":4.287178819113636e-05,"EnableGC":true,"DebugGC":false,"BySize":[{"Size":0,"Mallocs":0,"Frees":0},{"Size":8,"Mallocs":1031,"Frees":955},{"Size":16,"Mallocs":308485,"Frees":142064},{"Size":32,"Mallocs":64937,"Frees":54321},{"Size":48,"Mallocs":33012,"Frees":29754},{"Size":64,"Mallocs":20299,"Frees":18173},{"Size":80,"Mallocs":8186,"Frees":7597},{"Size":96,"Mallocs":9806,"Frees":8982},{"Size":112,"Mallocs":5671,"Frees":4850},{"Size":128,"Mallocs":2972,"Frees":2684},{"Size":144,"Mallocs":4106,"Frees":3719},{"Size":160,"Mallocs":1324,"Frees":911},{"Size":176,"Mallocs":2574,"Frees":2391},{"Size":192,"Mallocs":4053,"Frees":3863},{"Size":208,"Mallocs":442,"Frees":307},{"Size":224,"Mallocs":336,"Frees":172},{"Size":240,"Mallocs":143,"Frees":125},{"Size":256,"Mallocs":542,"Frees":497},{"Size":288,"Mallocs":15971,"Frees":14761},{"Size":320,"Mallocs":245,"Frees":30},{"Size":352,"Mallocs":1299,"Frees":1065},{"Size":384,"Mallocs":138,"Frees":2},{"Size":416,"Mallocs":54,"Frees":47},{"Size":448,"Mallocs":75,"Frees":29},{"Size":480,"Mallocs":6,"Frees":4},{"Size":512,"Mallocs":452,"Frees":422},{"Size":576,"Mallocs":486,"Frees":395},{"Size":640,"Mallocs":81,"Frees":67},{"Size":704,"Mallocs":421,"Frees":397},{"Size":768,"Mallocs":469,"Frees":468},{"Size":896,"Mallocs":1049,"Frees":1010},{"Size":1024,"Mallocs":1078,"Frees":960},{"Size":1152,"Mallocs":750,"Frees":498},{"Size":1280,"Mallocs":84,"Frees":72},{"Size":1408,"Mallocs":218,"Frees":187},{"Size":1536,"Mallocs":73,"Frees":48},{"Size":1664,"Mallocs":43,"Frees":30},{"Size":2048,"Mallocs":153,"Frees":57},{"Size":2304,"Mallocs":41,"Frees":30},{"Size":2560,"Mallocs":18,"Frees":15},{"Size":2816,"Mallocs":164,"Frees":157},{"Size":3072,"Mallocs":0,"Frees":0},{"Size":3328,"Mallocs":13,"Frees":6},{"Size":4096,"Mallocs":101,"Frees":82},{"Size":4608,"Mallocs":32,"Frees":26},{"Size":5376,"Mallocs":165,"Frees":151},{"Size":6144,"Mallocs":15,"Frees":9},{"Size":6400,"Mallocs":1,"Frees":1},{"Size":6656,"Mallocs":1,"Frees":0},{"Size":6912,"Mallocs":0,"Frees":0},{"Size":8192,"Mallocs":13,"Frees":13},{"Size":8448,"Mallocs":0,"Frees":0},{"Size":8704,"Mallocs":1,"Frees":1},{"Size":9472,"Mallocs":6,"Frees":4},{"Size":10496,"Mallocs":0,"Frees":0},{"Size":12288,"Mallocs":41,"Frees":35},{"Size":13568,"Mallocs":0,"Frees":0},{"Size":14080,"Mallocs":0,"Frees":0},{"Size":16384,"Mallocs":4,"Frees":4},{"Size":16640,"Mallocs":0,"Frees":0},{"Size":17664,"Mallocs":0,"Frees":0}]},
+"queryExecutor": {"name": "queryExecutor", "tags": null, "values": {}},
+"shard:/Users/csparr/.influxdb/data/_internal/monitor/2:2": {"name": "shard", "tags": {"database": "_internal", "engine": "tsm1", "id": "2", "path": "/Users/csparr/.influxdb/data/_internal/monitor/2", "retentionPolicy": "monitor"}, "values": {}},
+"shard:/Users/csparr/.influxdb/data/udp/default/1:1": {"name": "shard", "tags": {"database": "udp", "engine": "tsm1", "id": "1", "path": "/Users/csparr/.influxdb/data/udp/default/1", "retentionPolicy": "default"}, "values": {"fieldsCreate": 61, "seriesCreate": 33, "writePointsOk": 3613, "writeReq": 110}},
+"subscriber": {"name": "subscriber", "tags": null, "values": {"pointsWritten": 3613}},
+"tsm1_cache:/Users/csparr/.influxdb/data/_internal/monitor/2": {"name": "tsm1_cache", "tags": {"database": "_internal", "path": "/Users/csparr/.influxdb/data/_internal/monitor/2", "retentionPolicy": "monitor"}, "values": {"WALCompactionTimeMs": 0, "cacheAgeMs": 1103932, "cachedBytes": 0, "diskBytes": 0, "memBytes": 40480, "snapshotCount": 0}},
+"tsm1_cache:/Users/csparr/.influxdb/data/udp/default/1": {"name": "tsm1_cache", "tags": {"database": "udp", "path": "/Users/csparr/.influxdb/data/udp/default/1", "retentionPolicy": "default"}, "values": {"WALCompactionTimeMs": 0, "cacheAgeMs": 1103029, "cachedBytes": 0, "diskBytes": 0, "memBytes": 2359472, "snapshotCount": 0}},
+"tsm1_filestore:/Users/csparr/.influxdb/data/_internal/monitor/2": {"name": "tsm1_filestore", "tags": {"database": "_internal", "path": "/Users/csparr/.influxdb/data/_internal/monitor/2", "retentionPolicy": "monitor"}, "values": {}},
+"tsm1_filestore:/Users/csparr/.influxdb/data/udp/default/1": {"name": "tsm1_filestore", "tags": {"database": "udp", "path": "/Users/csparr/.influxdb/data/udp/default/1", "retentionPolicy": "default"}, "values": {}},
+"tsm1_wal:/Users/csparr/.influxdb/wal/_internal/monitor/2": {"name": "tsm1_wal", "tags": {"database": "_internal", "path": "/Users/csparr/.influxdb/wal/_internal/monitor/2", "retentionPolicy": "monitor"}, "values": {"currentSegmentDiskBytes": 0, "oldSegmentsDiskBytes": 69532}},
+"tsm1_wal:/Users/csparr/.influxdb/wal/udp/default/1": {"name": "tsm1_wal", "tags": {"database": "udp", "path": "/Users/csparr/.influxdb/wal/udp/default/1", "retentionPolicy": "default"}, "values": {"currentSegmentDiskBytes": 193728, "oldSegmentsDiskBytes": 1008330}},
+"write": {"name": "write", "tags": null, "values": {"pointReq": 3613, "pointReqLocal": 3613, "req": 110, "subWriteOk": 110, "writeOk": 110}}
+}`

plugins/inputs/statsd/statsd.go

@@ -24,7 +24,8 @@ const (
 
 	defaultFieldName = "value"
 
-	defaultSeparator = "_"
+	defaultSeparator           = "_"
+	defaultAllowPendingMessage = 10000
 )
 
 var dropwarn = "ERROR: statsd message queue full. " +
@@ -295,7 +296,7 @@ func (s *Statsd) udpListen() error {
 			case s.in <- bufCopy:
 			default:
 				s.drops++
-				if s.drops == 1 || s.drops%s.AllowedPendingMessages == 0 {
+				if s.drops == 1 || s.AllowedPendingMessages == 0 || s.drops%s.AllowedPendingMessages == 0 {
 					log.Printf(dropwarn, s.drops)
 				}
 			}
@@ -640,7 +641,8 @@ func (s *Statsd) Stop() {
 func init() {
 	inputs.Add("statsd", func() telegraf.Input {
 		return &Statsd{
-			MetricSeparator: "_",
+			MetricSeparator:        "_",
+			AllowedPendingMessages: defaultAllowPendingMessage,
 		}
 	})
 }

plugins/outputs/prometheus_client/prometheus_client.go

@@ -17,7 +17,8 @@ var invalidNameCharRE = regexp.MustCompile(`[^a-zA-Z0-9_]`)
 type PrometheusClient struct {
 	Listen string
 
-	metrics map[string]prometheus.Metric
+	metrics     map[string]prometheus.Metric
+	lastMetrics map[string]prometheus.Metric
 
 	sync.Mutex
 }
@@ -28,6 +29,8 @@ var sampleConfig = `
 `
 
 func (p *PrometheusClient) Start() error {
+	p.metrics = make(map[string]prometheus.Metric)
+	p.lastMetrics = make(map[string]prometheus.Metric)
 	prometheus.MustRegister(p)
 	defer func() {
 		if r := recover(); r != nil {
@@ -83,8 +86,17 @@ func (p *PrometheusClient) Collect(ch chan<- prometheus.Metric) {
 	p.Lock()
 	defer p.Unlock()
 
-	for _, m := range p.metrics {
-		ch <- m
+	if len(p.metrics) > 0 {
+		p.lastMetrics = make(map[string]prometheus.Metric)
+		for k, m := range p.metrics {
+			ch <- m
+			p.lastMetrics[k] = m
+		}
+		p.metrics = make(map[string]prometheus.Metric)
+	} else {
+		for _, m := range p.lastMetrics {
+			ch <- m
+		}
 	}
 }
 
@@ -92,8 +104,6 @@ func (p *PrometheusClient) Write(metrics []telegraf.Metric) error {
 	p.Lock()
 	defer p.Unlock()
 
-	p.metrics = make(map[string]prometheus.Metric)
-
 	if len(metrics) == 0 {
 		return nil
 	}