Adding new metric to keep track of total relayed lines

* Adding new simple test to relay package
* Adding metric testing on relay
* Adding new metric to relay
* Adding new test section to check on metrics
* Fixing linting problems on new code
* Adding license headers on file

Signed-off-by: Pedro Tanaka <pedro.tanaka@shopify.com>

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/prometheus/client_golang v1.11.0
 	github.com/prometheus/client_model v0.2.0
 	github.com/prometheus/common v0.30.0
+	github.com/stvp/go-udp-testing v0.0.0-20201019212854-469649b16807
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 	gopkg.in/yaml.v2 v2.4.0
 )

go.sum

@@ -190,6 +190,8 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/stvp/go-udp-testing v0.0.0-20201019212854-469649b16807 h1:LUsDduamlucuNnWcaTbXQ6aLILFcLXADpOzeEH3U+OI=
+github.com/stvp/go-udp-testing v0.0.0-20201019212854-469649b16807/go.mod h1:7jxmlfBCDBXRzr0eAQJ48XC1hBu1np4CS5+cHEYfwpc=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=

pkg/relay/relay.go

@@ -20,6 +20,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/prometheus/statsd_exporter/pkg/clock"
+
 	"github.com/go-kit/log"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -34,8 +36,9 @@ type Relay struct {
 	logger        log.Logger
 	packetLength  uint
 
-	packetsTotal   prometheus.Counter
-	longLinesTotal prometheus.Counter
+	packetsTotal      prometheus.Counter
+	longLinesTotal    prometheus.Counter
+	relayedLinesTotal prometheus.Counter
 }
 
 var (
@@ -53,6 +56,13 @@ var (
 		},
 		[]string{"target"},
 	)
+	relayLinesRelayedTotal = promauto.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "statsd_exporter_relay_lines_relayed_total",
+			Help: "The number of lines that were buffered to be relayed.",
+		},
+		[]string{"target"},
+	)
 )
 
 // NewRelay creates a statsd UDP relay. It can be used to send copies of statsd raw
@@ -76,8 +86,9 @@ func NewRelay(l log.Logger, target string, packetLength uint) (*Relay, error) {
 		logger:        l,
 		packetLength:  packetLength,
 
-		packetsTotal:   relayPacketsTotal.WithLabelValues(target),
-		longLinesTotal: relayLongLinesTotal.WithLabelValues(target),
+		packetsTotal:      relayPacketsTotal.WithLabelValues(target),
+		longLinesTotal:    relayLongLinesTotal.WithLabelValues(target),
+		relayedLinesTotal: relayLinesRelayedTotal.WithLabelValues(target),
 	}
 
 	// Startup the UDP sender.
@@ -91,7 +102,7 @@ func (r *Relay) relayOutput() {
 	var buffer bytes.Buffer
 	var err error
 
-	relayInterval := time.NewTicker(1 * time.Second)
+	relayInterval := clock.NewTicker(1 * time.Second)
 	defer relayInterval.Stop()
 
 	for {
@@ -151,5 +162,6 @@ func (r *Relay) RelayLine(l string) {
 	if !strings.HasSuffix(l, "\n") {
 		l = l + "\n"
 	}
+	r.relayedLinesTotal.Inc()
 	r.bufferChannel <- []byte(l)
 }

pkg/relay/relay_test.go

@@ -0,0 +1,167 @@
+// Copyright 2013 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package relay
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/statsd_exporter/pkg/clock"
+	"github.com/stvp/go-udp-testing"
+)
+
+func TestRelay_RelayLine(t *testing.T) {
+	type args struct {
+		lines    []string
+		expected string
+	}
+
+	tests := []struct {
+		name string
+		args args
+	}{
+		{
+			name: "multiple lines",
+			args: args{
+				lines:    []string{"foo5:100|c|#tag1:bar,#tag2:baz", "foo2:200|c|#tag1:bar,#tag2:baz"},
+				expected: "foo5:100|c|#tag1:bar,#tag2:baz\n",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		udp.SetAddr(":1160")
+		t.Run(tt.name, func(t *testing.T) {
+			tickerCh := make(chan time.Time)
+			clock.ClockInstance = &clock.Clock{
+				TickerCh: tickerCh,
+			}
+			clock.ClockInstance.Instant = time.Unix(0, 0)
+
+			logger := log.NewNopLogger()
+			r, err := NewRelay(
+				logger,
+				"localhost:1160",
+				200,
+			)
+
+			if err != nil {
+				t.Errorf("Did not expect error while creating relay.")
+			}
+
+			udp.ShouldReceive(t, tt.args.expected, func() {
+				for _, line := range tt.args.lines {
+					r.RelayLine(line)
+				}
+				// Tick time forward to trigger a packet send.
+				clock.ClockInstance.Instant = time.Unix(1, 10)
+				clock.ClockInstance.TickerCh <- time.Unix(0, 0)
+			})
+
+			metrics, err := prometheus.DefaultGatherer.Gather()
+			if err != nil {
+				t.Fatalf("Cannot gather from DefaultGatherer: %v", err)
+			}
+
+			metricNames := map[string]float64{
+				"statsd_exporter_relay_long_lines_total":    0,
+				"statsd_exporter_relay_lines_relayed_total": float64(len(tt.args.lines)),
+			}
+			for metricName, expectedValue := range metricNames {
+				metric := getFloat64(metrics, metricName, prometheus.Labels{"target": "localhost:1160"})
+
+				if metric == nil {
+					t.Fatalf("Could not find time series with first label set for metric: %s", metricName)
+				}
+				if *metric != expectedValue {
+					t.Errorf("Expected metric %s to be %f, got %f", metricName, expectedValue, *metric)
+				}
+			}
+
+			prometheus.Unregister(relayLongLinesTotal)
+			prometheus.Unregister(relayLinesRelayedTotal)
+		})
+	}
+}
+
+// getFloat64 search for metric by name in array of MetricFamily and then search a value by labels.
+// Method returns a value or nil if metric is not found.
+func getFloat64(metrics []*dto.MetricFamily, name string, labels prometheus.Labels) *float64 {
+	var metricFamily *dto.MetricFamily
+	for _, m := range metrics {
+		if *m.Name == name {
+			metricFamily = m
+			break
+		}
+	}
+	if metricFamily == nil {
+		return nil
+	}
+
+	var metric *dto.Metric
+	labelStr := fmt.Sprintf("%v", labels)
+	for _, m := range metricFamily.Metric {
+		l := labelPairsAsLabels(m.GetLabel())
+		ls := fmt.Sprintf("%v", l)
+		if labelStr == ls {
+			metric = m
+			break
+		}
+	}
+	if metric == nil {
+		return nil
+	}
+
+	var value float64
+	if metric.Gauge != nil {
+		value = metric.Gauge.GetValue()
+		return &value
+	}
+	if metric.Counter != nil {
+		value = metric.Counter.GetValue()
+		return &value
+	}
+	if metric.Histogram != nil {
+		value = metric.Histogram.GetSampleSum()
+		return &value
+	}
+	if metric.Summary != nil {
+		value = metric.Summary.GetSampleSum()
+		return &value
+	}
+	if metric.Untyped != nil {
+		value = metric.Untyped.GetValue()
+		return &value
+	}
+	panic(fmt.Errorf("collected a non-gauge/counter/histogram/summary/untyped metric: %s", metric))
+}
+
+func labelPairsAsLabels(pairs []*dto.LabelPair) (labels prometheus.Labels) {
+	labels = prometheus.Labels{}
+	for _, pair := range pairs {
+		if pair.Name == nil {
+			continue
+		}
+		value := ""
+		if pair.Value != nil {
+			value = *pair.Value
+		}
+		labels[*pair.Name] = value
+	}
+	return
+}