From 444dc96e39c266e613f2114159707c232bab86d7 Mon Sep 17 00:00:00 2001
From: Jan Safranek <jsafrane@redhat.com>
Date: Fri, 20 Nov 2020 14:18:43 +0100
Subject: [PATCH] Lower the frequency of volume plugin deprecation warning

The warning is always logged (klog.Warningf), so make sure it's logged only
once per process. We've seen clusters where the deprecation warning was
about 20% of total logs.
---
 pkg/volume/BUILD      |  1 +
 pkg/volume/plugins.go | 31 ++++++++++++++++++++-----------
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/pkg/volume/BUILD b/pkg/volume/BUILD
index e346c141720..5ad317b1232 100644
--- a/pkg/volume/BUILD
+++ b/pkg/volume/BUILD
@@ -28,6 +28,7 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/types:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/errors:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/validation:go_default_library",
         "//staging/src/k8s.io/client-go/informers:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
diff --git a/pkg/volume/plugins.go b/pkg/volume/plugins.go
index 9feccd04286..453d9a0129f 100644
--- a/pkg/volume/plugins.go
+++ b/pkg/volume/plugins.go
@@ -22,6 +22,7 @@ import (
 	"strings"
 	"sync"
 
+	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/klog/v2"
 	"k8s.io/utils/exec"
 	"k8s.io/utils/mount"
@@ -454,11 +455,12 @@ type VolumeHost interface {
 
 // VolumePluginMgr tracks registered plugins.
 type VolumePluginMgr struct {
-	mutex         sync.Mutex
-	plugins       map[string]VolumePlugin
-	prober        DynamicPluginProber
-	probedPlugins map[string]VolumePlugin
-	Host          VolumeHost
+	mutex                     sync.Mutex
+	plugins                   map[string]VolumePlugin
+	prober                    DynamicPluginProber
+	probedPlugins             map[string]VolumePlugin
+	loggedDeprecationWarnings sets.String
+	Host                      VolumeHost
 }
 
 // Spec is an internal representation of a volume.  All API volume types translate to Spec.
@@ -589,6 +591,7 @@ func (pm *VolumePluginMgr) InitPlugins(plugins []VolumePlugin, prober DynamicPlu
 	defer pm.mutex.Unlock()
 
 	pm.Host = host
+	pm.loggedDeprecationWarnings = sets.NewString()
 
 	if prober == nil {
 		// Use a dummy prober to prevent nil deference.
@@ -685,9 +688,7 @@ func (pm *VolumePluginMgr) FindPluginBySpec(spec *Spec) (VolumePlugin, error) {
 	}
 
 	// Issue warning if the matched provider is deprecated
-	if detail, ok := deprecatedVolumeProviders[matches[0].GetPluginName()]; ok {
-		klog.Warningf("WARNING: %s built-in volume provider is now deprecated. %s", matches[0].GetPluginName(), detail)
-	}
+	pm.logDeprecation(matches[0].GetPluginName())
 	return matches[0], nil
 }
 
@@ -720,12 +721,20 @@ func (pm *VolumePluginMgr) FindPluginByName(name string) (VolumePlugin, error) {
 	}
 
 	// Issue warning if the matched provider is deprecated
-	if detail, ok := deprecatedVolumeProviders[matches[0].GetPluginName()]; ok {
-		klog.Warningf("WARNING: %s built-in volume provider is now deprecated. %s", matches[0].GetPluginName(), detail)
-	}
+	pm.logDeprecation(matches[0].GetPluginName())
 	return matches[0], nil
 }
 
+// logDeprecation logs warning when a deprecated plugin is used.
+func (pm *VolumePluginMgr) logDeprecation(plugin string) {
+	if detail, ok := deprecatedVolumeProviders[plugin]; ok && !pm.loggedDeprecationWarnings.Has(plugin) {
+		klog.Warningf("WARNING: %s built-in volume provider is now deprecated. %s", plugin, detail)
+		// Make sure the message is logged only once. It has Warning severity
+		// and we don't want to spam the log too much.
+		pm.loggedDeprecationWarnings.Insert(plugin)
+	}
+}
+
 // Check if probedPlugin cache update is required.
 // If it is, initialize all probed plugins and replace the cache with them.
 func (pm *VolumePluginMgr) refreshProbedPlugins() {