From a07024722aa6bb5c844b34c7dc4715ee86173b0e Mon Sep 17 00:00:00 2001
From: Alex Collins <alex_collins@intuit.com>
Date: Wed, 29 Sep 2021 21:42:18 -0700
Subject: [PATCH] feat: log metrics on runner stop

---
 runner/sidecar/sidecar.go | 17 +++++++++++++++++
 shared/util/log.go        | 12 ++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/runner/sidecar/sidecar.go b/runner/sidecar/sidecar.go
index b1f7839a..bb6fa128 100644
--- a/runner/sidecar/sidecar.go
+++ b/runner/sidecar/sidecar.go
@@ -17,6 +17,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/prometheus/common/expfmt"
 	jaegercfg "github.com/uber/jaeger-client-go/config"
 	jaegerlog "github.com/uber/jaeger-client-go/log"
 	"github.com/uber/jaeger-lib/metrics"
@@ -95,6 +96,8 @@ func Exec(ctx context.Context) error {
 
 	opentracing.SetGlobalTracer(tracer)
 
+	addStopHook(logMetrics)
+
 	if err := enrichSpec(ctx); err != nil {
 		return err
 	}
@@ -202,6 +205,20 @@ func Exec(ctx context.Context) error {
 	return nil
 }
 
+func logMetrics(ctx context.Context) error {
+	families, err := prometheus.DefaultGatherer.Gather()
+	if err != nil {
+		return err
+	}
+	w := sharedutil.LogWriter(logger)
+	for _, f := range families {
+		if _, err := expfmt.MetricFamilyToText(w, f); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func enrichSpec(ctx context.Context) error {
 	if err := enrichSources(ctx); err != nil {
 		return err
diff --git a/shared/util/log.go b/shared/util/log.go
index 71cf7c7d..f72a4849 100644
--- a/shared/util/log.go
+++ b/shared/util/log.go
@@ -1,6 +1,7 @@
 package util
 
 import (
+	"io"
 	"os"
 
 	"github.com/bombsimon/logrusr"
@@ -13,3 +14,14 @@ func NewLogger() logr.Logger {
 	l.SetOutput(os.Stdout)
 	return logrusr.NewLogger(l)
 }
+
+type logWriter struct{ logr.Logger }
+
+func (l logWriter) Write(p []byte) (n int, err error) {
+	l.Info(string(p))
+	return len(p), nil
+}
+
+func LogWriter(l logr.Logger) io.Writer {
+	return logWriter{l}
+}