logging: add SetFilteredKlogLogger to show client-go throttling logs

go.mod

@@ -19,6 +19,7 @@ require (
 	k8s.io/apiextensions-apiserver v0.29.1
 	k8s.io/apimachinery v0.29.1
 	k8s.io/client-go v0.29.1
+	k8s.io/klog/v2 v2.110.1
 	sigs.k8s.io/controller-runtime v0.17.0
 	sigs.k8s.io/controller-tools v0.14.0
 	sigs.k8s.io/yaml v1.4.0
@@ -123,7 +124,6 @@ require (
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/component-base v0.29.1 // indirect
-	k8s.io/klog/v2 v2.110.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20231010175941-2dd684a91f00 // indirect
 	k8s.io/utils v0.0.0-20230726121419-3b25d923346b // indirect
 	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect

pkg/logging/klog.go

@@ -0,0 +1,61 @@
+// Copyright 2024 Upbound Inc.
+// All rights reserved
+
+package logging
+
+import (
+	"flag"
+	"os"
+	"strings"
+
+	"github.com/go-logr/logr"
+	"k8s.io/klog/v2"
+)
+
+// SetFilteredKlogLogger sets log as the logger backend of klog, but filtering
+// aggressively to avoid noise.
+func SetFilteredKlogLogger(log logr.Logger) {
+	// initialize klog at verbosity level 3, dropping everything higher.
+	fs := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+	klog.InitFlags(fs)
+	fs.Parse([]string{"--v=3"}) //nolint:errcheck // we couldn't do anything here anyway
+
+	klogr := logr.New(&requestThrottlingFilter{log.GetSink()})
+	klog.SetLogger(klogr)
+}
+
+// requestThrottlingFilter drops everything that is not a client-go throttling
+// message, compare:
+// https://github.com/kubernetes/client-go/blob/8c4efe8d079e405329f314fb789a41ac6af101dc/rest/request.go#L621
+type requestThrottlingFilter struct {
+	logr.LogSink
+}
+
+func (l *requestThrottlingFilter) Info(level int, msg string, keysAndValues ...interface{}) {
+	if !strings.Contains(msg, "Waited for ") || !strings.Contains(msg, "  request: ") {
+		return
+	}
+
+	l.LogSink.Info(l.klogToLogrLevel(level), msg, keysAndValues...)
+}
+
+func (l *requestThrottlingFilter) Enabled(level int) bool {
+	return l.LogSink.Enabled(l.klogToLogrLevel(level))
+}
+
+func (l *requestThrottlingFilter) klogToLogrLevel(klogLvl int) int {
+	// we want a default klog level of 3 for info, 4 for debug, corresponding to
+	// logr levels of 0 and 1.
+	if klogLvl >= 3 {
+		return klogLvl - 3
+	}
+	return 0
+}
+
+func (l *requestThrottlingFilter) WithCallDepth(depth int) logr.LogSink {
+	if delegate, ok := l.LogSink.(logr.CallDepthLogSink); ok {
+		return &requestThrottlingFilter{LogSink: delegate.WithCallDepth(depth)}
+	}
+
+	return l
+}