Add final aggregator (#5820)

plugins/aggregators/final/README.md

@@ -0,0 +1,48 @@
+# Final Aggregator Plugin
+
+The final aggregator emits the last metric of a contiguous series.  A
+contiguous series is defined as a series which receives updates within the
+time period in `series_timeout`. The contiguous series may be longer than the
+time interval defined by `period`.
+
+This is useful for getting the final value for data sources that produce
+discrete time series such as procstat, cgroup, kubernetes etc.
+
+When a series has not been updated within the time defined in
+`series_timeout`, the last metric is emitted with the `_final` appended.
+
+### Configuration
+
+```toml
+[[aggregators.final]]
+  ## The period on which to flush & clear the aggregator.
+  period = "30s"
+  ## If true, the original metric will be dropped by the
+  ## aggregator and will not get sent to the output plugins.
+  drop_original = false
+
+  ## The time that a series is not updated until considering it final.
+  series_timeout = "5m"
+```
+
+### Metrics
+
+Measurement and tags are unchanged, fields are emitted with the suffix
+`_final`.
+
+### Example Output
+
+```
+counter,host=bar i_final=3,j_final=6 1554281635115090133
+counter,host=foo i_final=3,j_final=6 1554281635112992012
+```
+
+Original input:
+```
+counter,host=bar i=1,j=4 1554281633101153300
+counter,host=foo i=1,j=4 1554281633099323601
+counter,host=bar i=2,j=5 1554281634107980073
+counter,host=foo i=2,j=5 1554281634105931116
+counter,host=bar i=3,j=6 1554281635115090133
+counter,host=foo i=3,j=6 1554281635112992012
+```

plugins/aggregators/final/final.go

@@ -0,0 +1,72 @@
+package final
+
+import (
+	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal"
+	"github.com/influxdata/telegraf/plugins/aggregators"
+)
+
+var sampleConfig = `
+  ## The period on which to flush & clear the aggregator.
+  period = "30s"
+  ## If true, the original metric will be dropped by the
+  ## aggregator and will not get sent to the output plugins.
+  drop_original = false
+
+  ## The time that a series is not updated until considering it final.
+  series_timeout = "5m"
+`
+
+type Final struct {
+	SeriesTimeout internal.Duration `toml:"series_timeout"`
+
+	// The last metric for all series which are active
+	metricCache map[uint64]telegraf.Metric
+}
+
+func NewFinal() *Final {
+	return &Final{
+		SeriesTimeout: internal.Duration{Duration: 5 * time.Minute},
+		metricCache:   make(map[uint64]telegraf.Metric),
+	}
+}
+
+func (m *Final) SampleConfig() string {
+	return sampleConfig
+}
+
+func (m *Final) Description() string {
+	return "Report the final metric of a series"
+}
+
+func (m *Final) Add(in telegraf.Metric) {
+	id := in.HashID()
+	m.metricCache[id] = in
+}
+
+func (m *Final) Push(acc telegraf.Accumulator) {
+	// Preserve timestamp of original metric
+	acc.SetPrecision(time.Nanosecond)
+
+	for id, metric := range m.metricCache {
+		if time.Since(metric.Time()) > m.SeriesTimeout.Duration {
+			fields := map[string]interface{}{}
+			for _, field := range metric.FieldList() {
+				fields[field.Key+"_final"] = field.Value
+			}
+			acc.AddFields(metric.Name(), fields, metric.Tags(), metric.Time())
+			delete(m.metricCache, id)
+		}
+	}
+}
+
+func (m *Final) Reset() {
+}
+
+func init() {
+	aggregators.Add("final", func() telegraf.Aggregator {
+		return NewFinal()
+	})
+}

plugins/aggregators/final/final_test.go

@@ -0,0 +1,144 @@
+package final
+
+import (
+	"testing"
+	"time"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/internal"
+	"github.com/influxdata/telegraf/metric"
+	"github.com/influxdata/telegraf/testutil"
+)
+
+func TestSimple(t *testing.T) {
+	acc := testutil.Accumulator{}
+	final := NewFinal()
+
+	tags := map[string]string{"foo": "bar"}
+	m1, _ := metric.New("m1",
+		tags,
+		map[string]interface{}{"a": int64(1)},
+		time.Unix(1530939936, 0))
+	m2, _ := metric.New("m1",
+		tags,
+		map[string]interface{}{"a": int64(2)},
+		time.Unix(1530939937, 0))
+	m3, _ := metric.New("m1",
+		tags,
+		map[string]interface{}{"a": int64(3)},
+		time.Unix(1530939938, 0))
+	final.Add(m1)
+	final.Add(m2)
+	final.Add(m3)
+	final.Push(&acc)
+
+	expected := []telegraf.Metric{
+		testutil.MustMetric(
+			"m1",
+			tags,
+			map[string]interface{}{
+				"a_final": 3,
+			},
+			time.Unix(1530939938, 0),
+		),
+	}
+	testutil.RequireMetricsEqual(t, expected, acc.GetTelegrafMetrics())
+}
+
+func TestTwoTags(t *testing.T) {
+	acc := testutil.Accumulator{}
+	final := NewFinal()
+
+	tags1 := map[string]string{"foo": "bar"}
+	tags2 := map[string]string{"foo": "baz"}
+
+	m1, _ := metric.New("m1",
+		tags1,
+		map[string]interface{}{"a": int64(1)},
+		time.Unix(1530939936, 0))
+	m2, _ := metric.New("m1",
+		tags2,
+		map[string]interface{}{"a": int64(2)},
+		time.Unix(1530939937, 0))
+	m3, _ := metric.New("m1",
+		tags1,
+		map[string]interface{}{"a": int64(3)},
+		time.Unix(1530939938, 0))
+	final.Add(m1)
+	final.Add(m2)
+	final.Add(m3)
+	final.Push(&acc)
+
+	expected := []telegraf.Metric{
+		testutil.MustMetric(
+			"m1",
+			tags2,
+			map[string]interface{}{
+				"a_final": 2,
+			},
+			time.Unix(1530939937, 0),
+		),
+		testutil.MustMetric(
+			"m1",
+			tags1,
+			map[string]interface{}{
+				"a_final": 3,
+			},
+			time.Unix(1530939938, 0),
+		),
+	}
+	testutil.RequireMetricsEqual(t, expected, acc.GetTelegrafMetrics(), testutil.SortMetrics())
+}
+
+func TestLongDifference(t *testing.T) {
+	acc := testutil.Accumulator{}
+	final := NewFinal()
+	final.SeriesTimeout = internal.Duration{Duration: 30 * time.Second}
+	tags := map[string]string{"foo": "bar"}
+
+	now := time.Now()
+
+	m1, _ := metric.New("m",
+		tags,
+		map[string]interface{}{"a": int64(1)},
+		now.Add(time.Second*-290))
+	m2, _ := metric.New("m",
+		tags,
+		map[string]interface{}{"a": int64(2)},
+		now.Add(time.Second*-275))
+	m3, _ := metric.New("m",
+		tags,
+		map[string]interface{}{"a": int64(3)},
+		now.Add(time.Second*-100))
+	m4, _ := metric.New("m",
+		tags,
+		map[string]interface{}{"a": int64(4)},
+		now.Add(time.Second*-20))
+	final.Add(m1)
+	final.Add(m2)
+	final.Push(&acc)
+	final.Add(m3)
+	final.Push(&acc)
+	final.Add(m4)
+	final.Push(&acc)
+
+	expected := []telegraf.Metric{
+		testutil.MustMetric(
+			"m",
+			tags,
+			map[string]interface{}{
+				"a_final": 2,
+			},
+			now.Add(time.Second*-275),
+		),
+		testutil.MustMetric(
+			"m",
+			tags,
+			map[string]interface{}{
+				"a_final": 3,
+			},
+			now.Add(time.Second*-100),
+		),
+	}
+	testutil.RequireMetricsEqual(t, expected, acc.GetTelegrafMetrics(), testutil.SortMetrics())
+}