Merge pull request #102133 from pacoxu/move-defaulting-kubeadm

kubeadm: move cgroupDriver defaulting to kubeconfig/kubelet.go Default()

cmd/kubeadm/app/cmd/init.go

@@ -37,7 +37,6 @@ import (
 	phases "k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/init"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
-	"k8s.io/kubernetes/cmd/kubeadm/app/componentconfigs"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/features"
 	certsphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/certs"
@@ -337,12 +336,6 @@ func newInitData(cmd *cobra.Command, args []string, options *initOptions, out io
 		return nil, err
 	}
 
-	// For new clusters we want to set the kubelet cgroup driver to "systemd" unless the user is explicit about it.
-	// Currently this cannot be as part of the kubelet defaulting (Default()) because the function is called for
-	// upgrades too, which can break existing nodes after a kubelet restart.
-	// TODO: https://github.com/kubernetes/kubeadm/issues/2376
-	componentconfigs.MutateCgroupDriver(&cfg.ClusterConfiguration)
-
 	ignorePreflightErrorsSet, err := validation.ValidateIgnorePreflightErrors(options.ignorePreflightErrors, cfg.NodeRegistration.IgnorePreflightErrors)
 	if err != nil {
 		return nil, err

cmd/kubeadm/app/cmd/upgrade/plan.go

@@ -91,10 +91,6 @@ func runPlan(flags *planFlags, args []string) error {
 		return errors.WithMessage(err, "[upgrade/versions] FATAL")
 	}
 
-	// Warn if the kubelet component config is missing an explicit 'cgroupDriver'.
-	// TODO: https://github.com/kubernetes/kubeadm/issues/2376
-	componentconfigs.WarnCgroupDriver(&cfg.ClusterConfiguration)
-
 	// No upgrades available
 	if len(availUpgrades) == 0 {
 		klog.V(1).Infoln("[upgrade/plan] Awesome, you're up-to-date! Enjoy!")

cmd/kubeadm/app/componentconfigs/kubelet.go

@@ -17,10 +17,8 @@ limitations under the License.
 package componentconfigs
 
 import (
-	"fmt"
 	"path/filepath"
 
-	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/util/version"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/klog/v2"
@@ -217,6 +215,10 @@ func (kc *kubeletConfig) Default(cfg *kubeadmapi.ClusterConfiguration, _ *kubead
 			kc.config.CgroupDriver = driver
 		}
 	}
+	if len(kc.config.CgroupDriver) == 0 {
+		klog.V(1).Infof("the value of KubeletConfiguration.cgroupDriver is empty; setting it to %q", constants.CgroupDriverSystemd)
+		kc.config.CgroupDriver = constants.CgroupDriverSystemd
+	}
 
 	ok, err := isServiceActive("systemd-resolved")
 	if err != nil {
@@ -241,54 +243,3 @@ func isServiceActive(name string) (bool, error) {
 	}
 	return initSystem.ServiceIsActive(name), nil
 }
-
-// TODO: https://github.com/kubernetes/kubeadm/issues/2376
-const cgroupDriverSystemd = "systemd"
-
-// MutateCgroupDriver can be called to set the KubeletConfiguration cgroup driver to systemd.
-// Currently this cannot be as part of Default() because the function is called for
-// upgrades too, which can break existing nodes after a kubelet restart.
-// TODO: https://github.com/kubernetes/kubeadm/issues/2376
-func MutateCgroupDriver(cfg *kubeadmapi.ClusterConfiguration) {
-	cc, k, err := getKubeletConfig(cfg)
-	if err != nil {
-		klog.Warningf(err.Error())
-		return
-	}
-	if len(k.CgroupDriver) == 0 {
-		klog.V(1).Infof("setting the KubeletConfiguration cgroupDriver to %q", cgroupDriverSystemd)
-		k.CgroupDriver = cgroupDriverSystemd
-		cc.Set(k)
-	}
-}
-
-// WarnCgroupDriver prints a warning in case the user is not explicit
-// about the cgroupDriver value in the KubeletConfiguration.
-// TODO: https://github.com/kubernetes/kubeadm/issues/2376
-func WarnCgroupDriver(cfg *kubeadmapi.ClusterConfiguration) {
-	_, k, err := getKubeletConfig(cfg)
-	if err != nil {
-		klog.Warningf(err.Error())
-		return
-	}
-	if len(k.CgroupDriver) == 0 {
-		klog.Warningf("The 'cgroupDriver' value in the KubeletConfiguration is empty. " +
-			"Starting from 1.22, 'kubeadm upgrade' will default an empty value to the 'systemd' cgroup driver. " +
-			"The cgroup driver between the container runtime and the kubelet must match! " +
-			"To learn more about this see: https://kubernetes.io/docs/setup/production-environment/container-runtimes/")
-	}
-}
-
-// TODO: https://github.com/kubernetes/kubeadm/issues/2376
-func getKubeletConfig(cfg *kubeadmapi.ClusterConfiguration) (kubeadmapi.ComponentConfig, *kubeletconfig.KubeletConfiguration, error) {
-	errStr := fmt.Sprintf("setting the KubeletConfiguration cgroupDriver to %q failed unexpectedly", cgroupDriverSystemd)
-	cc, ok := cfg.ComponentConfigs[KubeletGroup]
-	if !ok {
-		return nil, nil, errors.Errorf("%s: %s", errStr, "missing kubelet component config")
-	}
-	k, ok := cc.Get().(*kubeletconfig.KubeletConfiguration)
-	if !ok {
-		return nil, nil, errors.Errorf("%s: %s", errStr, "incompatible KubeletConfiguration")
-	}
-	return cc, k, nil
-}

cmd/kubeadm/app/componentconfigs/kubelet_test.go

@@ -87,6 +87,7 @@ func TestKubeletDefault(t *testing.T) {
 					HealthzPort:        utilpointer.Int32Ptr(constants.KubeletHealthzPort),
 					RotateCertificates: kubeletRotateCertificates,
 					ResolverConfig:     resolverConfig,
+					CgroupDriver:       constants.CgroupDriverSystemd,
 				},
 			},
 		},
@@ -120,6 +121,7 @@ func TestKubeletDefault(t *testing.T) {
 					HealthzPort:        utilpointer.Int32Ptr(constants.KubeletHealthzPort),
 					RotateCertificates: kubeletRotateCertificates,
 					ResolverConfig:     resolverConfig,
+					CgroupDriver:       constants.CgroupDriverSystemd,
 				},
 			},
 		},
@@ -158,6 +160,7 @@ func TestKubeletDefault(t *testing.T) {
 					HealthzPort:        utilpointer.Int32Ptr(constants.KubeletHealthzPort),
 					RotateCertificates: kubeletRotateCertificates,
 					ResolverConfig:     resolverConfig,
+					CgroupDriver:       constants.CgroupDriverSystemd,
 				},
 			},
 		},
@@ -196,6 +199,7 @@ func TestKubeletDefault(t *testing.T) {
 					HealthzPort:        utilpointer.Int32Ptr(constants.KubeletHealthzPort),
 					RotateCertificates: kubeletRotateCertificates,
 					ResolverConfig:     resolverConfig,
+					CgroupDriver:       constants.CgroupDriverSystemd,
 				},
 			},
 		},
@@ -230,6 +234,7 @@ func TestKubeletDefault(t *testing.T) {
 					HealthzPort:        utilpointer.Int32Ptr(constants.KubeletHealthzPort),
 					RotateCertificates: kubeletRotateCertificates,
 					ResolverConfig:     resolverConfig,
+					CgroupDriver:       constants.CgroupDriverSystemd,
 				},
 			},
 		},
@@ -261,6 +266,7 @@ func TestKubeletDefault(t *testing.T) {
 					HealthzPort:        utilpointer.Int32Ptr(constants.KubeletHealthzPort),
 					RotateCertificates: kubeletRotateCertificates,
 					ResolverConfig:     resolverConfig,
+					CgroupDriver:       constants.CgroupDriverSystemd,
 				},
 			},
 		},

cmd/kubeadm/app/constants/constants.go

@@ -395,6 +395,11 @@ const (
 
 	// PauseVersion indicates the default pause image version for kubeadm
 	PauseVersion = "3.4.1"
+
+	// CgroupDriverSystemd holds the systemd driver type
+	CgroupDriverSystemd = "systemd"
+	// CgroupDriverCgroupfs holds the cgroupfs driver type
+	CgroupDriverCgroupfs = "cgroupfs"
 )
 
 var (

cmd/kubeadm/app/preflight/checks_linux.go

@@ -22,6 +22,7 @@ import (
 	"syscall"
 
 	"github.com/pkg/errors"
+	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 	"k8s.io/utils/exec"
 )
@@ -32,12 +33,12 @@ func (idsc IsDockerSystemdCheck) Check() (warnings, errorList []error) {
 	if err != nil {
 		return nil, []error{err}
 	}
-	if driver != kubeadmutil.CgroupDriverSystemd {
+	if driver != constants.CgroupDriverSystemd {
 		err = errors.Errorf("detected %q as the Docker cgroup driver. "+
 			"The recommended driver is %q. "+
 			"Please follow the guide at https://kubernetes.io/docs/setup/cri/",
 			driver,
-			kubeadmutil.CgroupDriverSystemd)
+			constants.CgroupDriverSystemd)
 		return []error{err}, nil
 	}
 	return nil, nil

cmd/kubeadm/app/util/cgroupdriver.go

@@ -24,13 +24,6 @@ import (
 	utilsexec "k8s.io/utils/exec"
 )
 
-const (
-	// CgroupDriverSystemd holds the systemd driver type
-	CgroupDriverSystemd = "systemd"
-	// CgroupDriverCgroupfs holds the cgroupfs driver type
-	CgroupDriverCgroupfs = "cgroupfs"
-)
-
 // TODO: add support for detecting the cgroup driver for CRI other than
 // Docker. Currently only Docker driver detection is supported:
 // Discussion:

cmd/kubeadm/app/util/cgroupdriver_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package util
 
 import (
+	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"testing"
 )
 
@@ -50,7 +51,7 @@ func TestGetCgroupDriverDocker(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			result := tc.driver != CgroupDriverCgroupfs && tc.driver != CgroupDriverSystemd
+			result := tc.driver != constants.CgroupDriverCgroupfs && tc.driver != constants.CgroupDriverSystemd
 			if result != tc.expectedError {
 				t.Fatalf("expected error: %v, saw: %v", tc.expectedError, result)
 			}