[release-4.20] OCPBUGS-65777: Enforce OCP 4.20 and earlier cluster to have AutoSizingReserved disabled by default

pkg/controller/bootstrap/bootstrap.go

@@ -208,6 +208,14 @@ func (b *Bootstrap) Run(destDir string) error {
 	}
 	klog.Infof("Successfully generated MachineConfigs from feature gates.")
 
+	// Generate auto-sizing MachineConfigs for all pools
+	autoSizingConfigs, err := kubeletconfig.RunAutoSizingBootstrap(pools)
+	if err != nil {
+		return err
+	}
+	configs = append(configs, autoSizingConfigs...)
+	klog.Infof("Successfully generated auto-sizing MachineConfigs.")
+
 	if nodeConfig == nil {
 		nodeConfig = &apicfgv1.Node{
 			ObjectMeta: metav1.ObjectMeta{

pkg/controller/kubelet-config/kubelet_config_autosizing.go

@@ -0,0 +1,138 @@
+package kubeletconfig
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/clarketm/json"
+	mcfgv1 "github.com/openshift/api/machineconfiguration/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/client-go/util/retry"
+	"k8s.io/klog/v2"
+
+	ctrlcommon "github.com/openshift/machine-config-operator/pkg/controller/common"
+)
+
+const (
+	AutoSizingEnvFilePath = "/etc/node-sizing-enabled.env"
+
+	AutoSizingMachineConfigNamePrefix = "50-%s-auto-sizing-disabled"
+
+	DefaultAutoSizingEnvContent = `NODE_SIZING_ENABLED=false
+SYSTEM_RESERVED_MEMORY=1Gi
+SYSTEM_RESERVED_CPU=500m
+SYSTEM_RESERVED_ES=1Gi
+`
+)
+
+// ensureAutoSizingMachineConfigs ensures auto-sizing MachineConfigs exist for all MachineConfigPools
+func (ctrl *Controller) ensureAutoSizingMachineConfigs(ctx context.Context) error {
+	mcpPools, err := ctrl.mcpLister.List(labels.Everything())
+	if err != nil {
+		return fmt.Errorf("could not list MachineConfigPools: %w", err)
+	}
+
+	for _, pool := range mcpPools {
+		if err := ctrl.createAutoSizingMCIfNeeded(ctx, pool); err != nil {
+			return fmt.Errorf("could not ensure auto-sizing MachineConfig for pool %v: %w", pool.Name, err)
+		}
+	}
+
+	return nil
+}
+
+// createAutoSizingMCIfNeeded creates an auto-sizing MachineConfig for a given pool if it doesn't exist
+func (ctrl *Controller) createAutoSizingMCIfNeeded(ctx context.Context, pool *mcfgv1.MachineConfigPool) error {
+	autoSizingKey := fmt.Sprintf(AutoSizingMachineConfigNamePrefix, pool.Name)
+
+	_, err := ctrl.client.MachineconfigurationV1().MachineConfigs().Get(ctx, autoSizingKey, metav1.GetOptions{})
+	autoSizingIsNotFound := errors.IsNotFound(err)
+
+	if err != nil && !autoSizingIsNotFound {
+		return err
+	}
+
+	// Only create the auto-sizing MachineConfig if it doesn't exist
+	if autoSizingIsNotFound {
+		autoSizingMC, err := newAutoSizingMachineConfig(pool)
+		if err != nil {
+			return err
+		}
+
+		// Create the auto-sizing MachineConfig
+		if err := retry.RetryOnConflict(updateBackoff, func() error {
+			_, err := ctrl.client.MachineconfigurationV1().MachineConfigs().Create(ctx, autoSizingMC, metav1.CreateOptions{})
+			return err
+		}); err != nil {
+			return fmt.Errorf("could not create auto-sizing MachineConfig, error: %w", err)
+		}
+
+		klog.Infof("Created auto-sizing configuration %v on MachineConfigPool %v", autoSizingKey, pool.Name)
+	} else {
+		klog.V(4).Infof("Auto-sizing MachineConfig %v already exists for pool %v, skipping creation", autoSizingKey, pool.Name)
+	}
+
+	return nil
+}
+
+// RunAutoSizingBootstrap generates auto-sizing MachineConfig objects for all mcpPools
+func RunAutoSizingBootstrap(mcpPools []*mcfgv1.MachineConfigPool) ([]*mcfgv1.MachineConfig, error) {
+	configs := make([]*mcfgv1.MachineConfig, 0, len(mcpPools))
+
+	// Create auto-sizing MachineConfigs for each pool
+	for _, pool := range mcpPools {
+		autoSizingMC, err := newAutoSizingMachineConfig(pool)
+		if err != nil {
+			return nil, err
+		}
+
+		configs = append(configs, autoSizingMC)
+	}
+
+	return configs, nil
+}
+
+// newAutoSizingMachineConfig creates an auto-sizing MachineConfig for a given pool
+func newAutoSizingMachineConfig(pool *mcfgv1.MachineConfigPool) (*mcfgv1.MachineConfig, error) {
+	autoSizingDisabledMCName := fmt.Sprintf(AutoSizingMachineConfigNamePrefix, pool.Name)
+
+	ignConfig := ctrlcommon.NewIgnConfig()
+
+	autoSizingMC, err := ctrlcommon.MachineConfigFromIgnConfig(pool.Name, autoSizingDisabledMCName, ignConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	rawAutoSizingIgn, err := createAutoSizingIgnConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	autoSizingMC.Spec.Config.Raw = rawAutoSizingIgn
+	// Do not add GeneratedByControllerVersionAnnotationKey annotation to auto-sizing MachineConfig. It will fail upgrade.
+	// This annotation is added for informing the user that the auto-sizing MachineConfig was added in a patch release
+	// to identify clusters created before 4.21 release.
+	autoSizingMC.ObjectMeta.Annotations = map[string]string{
+		"openshift-patch-reference": "machineConfig-to-set-the-default-behavior-of-NODE_SIZING_ENABLED",
+	}
+
+	return autoSizingMC, nil
+}
+
+// createAutoSizingIgnConfig creates the Ignition config with environment variables
+// to disable auto-sizing of system reserved resources
+func createAutoSizingIgnConfig() ([]byte, error) {
+	autoSizingFile := ctrlcommon.NewIgnFileBytes(AutoSizingEnvFilePath, []byte(DefaultAutoSizingEnvContent))
+
+	autoSizingIgnConfig := ctrlcommon.NewIgnConfig()
+	autoSizingIgnConfig.Storage.Files = append(autoSizingIgnConfig.Storage.Files, autoSizingFile)
+
+	rawAutoSizingIgn, err := json.Marshal(autoSizingIgnConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	return rawAutoSizingIgn, nil
+}