From 5dc80983de3a89dc9d63bdeefbdff64e34317023 Mon Sep 17 00:00:00 2001
From: Alexander Yastrebov <alexander.yastrebov@zalando.de>
Date: Mon, 22 Apr 2024 10:20:39 +0200
Subject: [PATCH] proxy: support configurable metrics (#3027)

Use configed metrics and fallback to global for backwards compatibility.

Updates #3026

Signed-off-by: Alexander Yastrebov <alexander.yastrebov@zalando.de>
---
 proxy/metrics_test.go |  9 ++++-----
 proxy/proxy.go        | 10 +++++++++-
 skipper.go            | 11 ++++++-----
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/proxy/metrics_test.go b/proxy/metrics_test.go
index 5342f2adcf..f601c4e319 100644
--- a/proxy/metrics_test.go
+++ b/proxy/metrics_test.go
@@ -9,19 +9,15 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/zalando/skipper/filters/builtin"
-	"github.com/zalando/skipper/metrics"
 	"github.com/zalando/skipper/metrics/metricstest"
+	"github.com/zalando/skipper/proxy"
 	"github.com/zalando/skipper/proxy/proxytest"
 	"github.com/zalando/skipper/routing"
 	"github.com/zalando/skipper/routing/testdataclient"
 )
 
 func TestMetricsUncompressed(t *testing.T) {
-	dm := metrics.Default
-	t.Cleanup(func() { metrics.Default = dm })
-
 	m := &metricstest.MockMetrics{}
-	metrics.Default = m
 
 	// will update routes after proxy address is known
 	dc := testdataclient.New(nil)
@@ -32,6 +28,9 @@ func TestMetricsUncompressed(t *testing.T) {
 			FilterRegistry: builtin.MakeRegistry(),
 			DataClients:    []routing.DataClient{dc},
 		},
+		ProxyParams: proxy.Params{
+			Metrics: m,
+		},
 	}.Create()
 	defer p.Close()
 
diff --git a/proxy/proxy.go b/proxy/proxy.go
index d2156d8f55..6e0616530b 100644
--- a/proxy/proxy.go
+++ b/proxy/proxy.go
@@ -217,6 +217,10 @@ type Params struct {
 	// Control flags. See the Flags values.
 	Flags Flags
 
+	// Metrics collector.
+	// If not specified proxy uses global metrics.Default.
+	Metrics metrics.Metrics
+
 	// And optional list of priority routes to be used for matching
 	// before the general lookup tree.
 	PriorityRoutes []PriorityRoute
@@ -766,7 +770,11 @@ func WithParams(p Params) *Proxy {
 		}
 	}
 
-	m := metrics.Default
+	m := p.Metrics
+	if m == nil {
+		m = metrics.Default
+	}
+
 	if p.Flags.Debug() {
 		m = metrics.Void
 	}
diff --git a/skipper.go b/skipper.go
index ef179a5252..c7e9aa2d71 100644
--- a/skipper.go
+++ b/skipper.go
@@ -1309,9 +1309,8 @@ func listenAndServeQuit(
 	}
 
 	if o.EnableConnMetricsServer {
-		m := metrics.Default
 		srv.ConnState = func(conn net.Conn, state http.ConnState) {
-			m.IncCounter(fmt.Sprintf("lb-conn-%s", state))
+			mtr.IncCounter(fmt.Sprintf("lb-conn-%s", state))
 		}
 	}
 
@@ -1521,6 +1520,7 @@ func run(o Options, sig chan os.Signal, idleConnsCH chan struct{}) error {
 	if mtr == nil {
 		mtr = metrics.NewMetrics(mtrOpts)
 	}
+	// set global instance for backwards compatibility
 	metrics.Default = mtr
 
 	// *DEPRECATED* client tracking parameter
@@ -2010,10 +2010,8 @@ func run(o Options, sig chan os.Signal, idleConnsCH chan struct{}) error {
 	proxyFlags := proxy.Flags(o.ProxyOptions) | o.ProxyFlags
 	proxyParams := proxy.Params{
 		Routing:                    routing,
-		EndpointRegistry:           endpointRegistry,
-		EnablePassiveHealthCheck:   passiveHealthCheckEnabled,
-		PassiveHealthCheck:         passiveHealthCheck,
 		Flags:                      proxyFlags,
+		Metrics:                    mtr,
 		PriorityRoutes:             o.PriorityRoutes,
 		IdleConnectionsPerHost:     o.IdleConnectionsPerHost,
 		CloseIdleConnsPeriod:       o.CloseIdleConnsPeriod,
@@ -2034,6 +2032,9 @@ func run(o Options, sig chan os.Signal, idleConnsCH chan struct{}) error {
 		ClientTLS:                  o.ClientTLS,
 		CustomHttpRoundTripperWrap: o.CustomHttpRoundTripperWrap,
 		RateLimiters:               ratelimitRegistry,
+		EndpointRegistry:           endpointRegistry,
+		EnablePassiveHealthCheck:   passiveHealthCheckEnabled,
+		PassiveHealthCheck:         passiveHealthCheck,
 	}
 
 	if o.EnableBreakers || len(o.BreakerSettings) > 0 {