Merge pull request #120174 from pohly/apiserver-etcd-metrics-race

apiserver: fix data race in etcd metrics

staging/src/k8s.io/apiserver/pkg/storage/etcd3/metrics/metrics.go

@@ -228,7 +228,7 @@ func UpdateEtcdDbSize(ep string, size int64) {
 
 // SetStorageMonitorGetter sets monitor getter to allow monitoring etcd stats.
 func SetStorageMonitorGetter(getter func() ([]Monitor, error)) {
-	storageMonitor.monitorGetter = getter
+	storageMonitor.setGetter(getter)
 }
 
 // UpdateLeaseObjectCount sets the etcd_lease_object_counts metric.
@@ -258,9 +258,22 @@ type StorageMetrics struct {
 type monitorCollector struct {
 	compbasemetrics.BaseStableCollector
 
+	mutex         sync.Mutex
 	monitorGetter func() ([]Monitor, error)
 }
 
+func (m *monitorCollector) setGetter(monitorGetter func() ([]Monitor, error)) {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+	m.monitorGetter = monitorGetter
+}
+
+func (m *monitorCollector) getGetter() func() ([]Monitor, error) {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+	return m.monitorGetter
+}
+
 // DescribeWithStability implements compbasemetrics.StableColletor
 func (c *monitorCollector) DescribeWithStability(ch chan<- *compbasemetrics.Desc) {
 	ch <- storageSizeDescription
@@ -268,7 +281,7 @@ func (c *monitorCollector) DescribeWithStability(ch chan<- *compbasemetrics.Desc
 
 // CollectWithStability implements compbasemetrics.StableColletor
 func (c *monitorCollector) CollectWithStability(ch chan<- compbasemetrics.Metric) {
-	monitors, err := c.monitorGetter()
+	monitors, err := c.getGetter()()
 	if err != nil {
 		return
 	}