Add machine annotation to specify MaxParallelImagePulls

pkg/apis/cluster/common/consts.go

@@ -134,6 +134,7 @@ const (
 	ExternalCloudProviderKubeletFlag KubeletFlags = "ExternalCloudProvider"
 )
 
+// Annotation suffixes, used with the KubeletConfig prefix, used on Machine objects to set fields of the KubeletConfig
 const (
 	SystemReservedKubeletConfig              = "SystemReserved"
 	KubeReservedKubeletConfig                = "KubeReserved"
@@ -143,10 +144,11 @@ const (
 	MaxPodsKubeletConfig                     = "MaxPods"
 	ImageGCLowThresholdPercentKubeletConfig  = "ImageGCLowThresholdPercent"
 	ImageGCHighThresholdPercentKubeletConfig = "ImageGCHighThresholdPercent"
+	MaxParallelImagePullsKubeletConfig       = "MaxParallelImagePulls"
 )
 
+// Annotation prefixes, used on Machine objects to indicate the parameters that been used to create those Machines.
 const (
-	// Annotation prefixes, used on Machine objects to indicate the parameters that been used to create those Machines.
 	KubeletFeatureGatesAnnotationPrefixV1 = "v1.kubelet-featuregates.machine-controller.kubermatic.io"
 	KubeletFlagsGroupAnnotationPrefixV1   = "v1.kubelet-flags.machine-controller.kubermatic.io"
 	KubeletConfigAnnotationPrefixV1       = "v1.kubelet-config.machine-controller.kubermatic.io"

pkg/userdata/helper/kubelet.go

@@ -317,6 +317,18 @@ func kubeletConfiguration(log *zap.SugaredLogger, clusterDomain string, clusterD
 		}
 	}
 
+	if maxParallelImagePulls, ok := kubeletConfigs[common.MaxParallelImagePullsKubeletConfig]; ok {
+		val, err := strconv.ParseInt(maxParallelImagePulls, 10, 32)
+		if err != nil || val < 0 {
+			// Instead of breaking the workflow, just print a warning and skip the configuration
+			log.Info("Skipping invalid MaxParallelImagePulls value for Kubelet configuration", "value", maxParallelImagePulls)
+		} else {
+			i32val := int32(val)
+			cfg.SerializeImagePulls = ptr.To(false)
+			cfg.MaxParallelImagePulls = &i32val
+		}
+	}
+
 	if enabled, ok := featureGates["SeccompDefault"]; ok && enabled {
 		cfg.SeccompDefault = ptr.To(true)
 	}