renaming plugins -> inputs

plugins/outputs/prometheus_client/README.md

@@ -0,0 +1,6 @@
+# Prometheus Client Service Output Plugin
+
+This plugin starts a Prometheus Client, listening on a port defined in the
+configuration file.
+
+It exposes all metrics on `/metrics` to be polled by a Prometheus server.

plugins/outputs/prometheus_client/prometheus_client.go

@@ -0,0 +1,125 @@
+package prometheus_client
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/influxdb/influxdb/client/v2"
+	"github.com/influxdb/telegraf/plugins/outputs"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type PrometheusClient struct {
+	Listen  string
+	metrics map[string]*prometheus.UntypedVec
+}
+
+var sampleConfig = `
+  # Address to listen on
+  # listen = ":9126"
+`
+
+func (p *PrometheusClient) Start() error {
+	if p.Listen == "" {
+		p.Listen = "localhost:9126"
+	}
+
+	http.Handle("/metrics", prometheus.Handler())
+	server := &http.Server{
+		Addr: p.Listen,
+	}
+
+	p.metrics = make(map[string]*prometheus.UntypedVec)
+	go server.ListenAndServe()
+	return nil
+}
+
+func (p *PrometheusClient) Stop() {
+	// TODO: Use a listener for http.Server that counts active connections
+	//       that can be stopped and closed gracefully
+}
+
+func (p *PrometheusClient) Connect() error {
+	// This service output does not need to make any further connections
+	return nil
+}
+
+func (p *PrometheusClient) Close() error {
+	// This service output does not need to close any of its connections
+	return nil
+}
+
+func (p *PrometheusClient) SampleConfig() string {
+	return sampleConfig
+}
+
+func (p *PrometheusClient) Description() string {
+	return "Configuration for the Prometheus client to spawn"
+}
+
+func (p *PrometheusClient) Write(points []*client.Point) error {
+	if len(points) == 0 {
+		return nil
+	}
+
+	for _, point := range points {
+		var labels []string
+		key := point.Name()
+
+		for k, _ := range point.Tags() {
+			if len(k) > 0 {
+				labels = append(labels, k)
+			}
+		}
+
+		if _, ok := p.metrics[key]; !ok {
+			p.metrics[key] = prometheus.NewUntypedVec(
+				prometheus.UntypedOpts{
+					Name: key,
+					Help: fmt.Sprintf("Telegraf collected point '%s'", key),
+				},
+				labels,
+			)
+			prometheus.MustRegister(p.metrics[key])
+		}
+
+		l := prometheus.Labels{}
+		for tk, tv := range point.Tags() {
+			l[tk] = tv
+		}
+
+		for _, val := range point.Fields() {
+			switch val := val.(type) {
+			default:
+				log.Printf("Prometheus output, unsupported type. key: %s, type: %T\n",
+					key, val)
+			case int64:
+				m, err := p.metrics[key].GetMetricWith(l)
+				if err != nil {
+					log.Printf("ERROR Getting metric in Prometheus output, "+
+						"key: %s, labels: %v,\nerr: %s\n",
+						key, l, err.Error())
+					continue
+				}
+				m.Set(float64(val))
+			case float64:
+				m, err := p.metrics[key].GetMetricWith(l)
+				if err != nil {
+					log.Printf("ERROR Getting metric in Prometheus output, "+
+						"key: %s, labels: %v,\nerr: %s\n",
+						key, l, err.Error())
+					continue
+				}
+				m.Set(val)
+			}
+		}
+	}
+	return nil
+}
+
+func init() {
+	outputs.Add("prometheus_client", func() outputs.Output {
+		return &PrometheusClient{}
+	})
+}

plugins/outputs/prometheus_client/prometheus_client_test.go

@@ -0,0 +1,100 @@
+package prometheus_client
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/influxdb/influxdb/client/v2"
+	"github.com/influxdb/telegraf/plugins/inputs/prometheus"
+	"github.com/influxdb/telegraf/testutil"
+)
+
+var pTesting *PrometheusClient
+
+func TestPrometheusWritePointEmptyTag(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	p := &prometheus.Prometheus{
+		Urls: []string{"http://localhost:9126/metrics"},
+	}
+	tags := make(map[string]string)
+	pt1, _ := client.NewPoint(
+		"test_point_1",
+		tags,
+		map[string]interface{}{"value": 0.0})
+	pt2, _ := client.NewPoint(
+		"test_point_2",
+		tags,
+		map[string]interface{}{"value": 1.0})
+	var points = []*client.Point{
+		pt1,
+		pt2,
+	}
+	require.NoError(t, pTesting.Write(points))
+
+	expected := []struct {
+		name  string
+		value float64
+		tags  map[string]string
+	}{
+		{"test_point_1", 0.0, tags},
+		{"test_point_2", 1.0, tags},
+	}
+
+	var acc testutil.Accumulator
+
+	require.NoError(t, p.Gather(&acc))
+	for _, e := range expected {
+		acc.AssertContainsFields(t, "prometheus_"+e.name,
+			map[string]interface{}{"value": e.value})
+	}
+}
+
+func TestPrometheusWritePointTag(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	p := &prometheus.Prometheus{
+		Urls: []string{"http://localhost:9126/metrics"},
+	}
+	tags := make(map[string]string)
+	tags["testtag"] = "testvalue"
+	pt1, _ := client.NewPoint(
+		"test_point_3",
+		tags,
+		map[string]interface{}{"value": 0.0})
+	pt2, _ := client.NewPoint(
+		"test_point_4",
+		tags,
+		map[string]interface{}{"value": 1.0})
+	var points = []*client.Point{
+		pt1,
+		pt2,
+	}
+	require.NoError(t, pTesting.Write(points))
+
+	expected := []struct {
+		name  string
+		value float64
+	}{
+		{"test_point_3", 0.0},
+		{"test_point_4", 1.0},
+	}
+
+	var acc testutil.Accumulator
+
+	require.NoError(t, p.Gather(&acc))
+	for _, e := range expected {
+		acc.AssertContainsFields(t, "prometheus_"+e.name,
+			map[string]interface{}{"value": e.value})
+	}
+}
+
+func init() {
+	pTesting = &PrometheusClient{Listen: "localhost:9126"}
+	pTesting.Start()
+}