kubeadm: add structured ExtraArgs in v1beta4

Add a new type Arg that holds a dedicated Name and Value.
Instead of using map[string]string for ExtraArgs in the
API use []Arg.

Adapt v1beta3 conversion to convert to/from the
legacy map[string]string.

cmd/kubeadm/app/apis/kubeadm/types.go

@@ -145,11 +145,10 @@ type ClusterConfiguration struct {
 // ControlPlaneComponent holds settings common to control plane component of the cluster
 type ControlPlaneComponent struct {
 	// ExtraArgs is an extra set of flags to pass to the control plane component.
-	// A key in this map is the flag name as it appears on the
+	// An argument name in this list is the flag name as it appears on the
-	// command line except without leading dash(es).
+	// command line except without leading dash(es). Extra arguments will override existing
-	// TODO: This is temporary and ideally we would like to switch all components to
+	// default arguments. Duplicate extra arguments are allowed.
-	// use ComponentConfig + ConfigMaps.
+	ExtraArgs []Arg
-	ExtraArgs map[string]string
 
 	// ExtraVolumes is an extra set of host volumes, mounted to the control plane component.
 	ExtraVolumes []HostPathMount
@@ -220,9 +219,9 @@ type NodeRegistrationOptions struct {
 	// KubeletExtraArgs passes through extra arguments to the kubelet. The arguments here are passed to the kubelet command line via the environment file
 	// kubeadm writes at runtime for the kubelet to source. This overrides the generic base-level configuration in the kubelet-config ConfigMap
 	// Flags have higher priority when parsing. These values are local and specific to the node kubeadm is executing on.
-	// A key in this map is the flag name as it appears on the
+	// An argument name in this list is the flag name as it appears on the command line except without leading dash(es).
-	// command line except without leading dash(es).
+	// Extra arguments will override existing default arguments. Duplicate extra arguments are allowed.
-	KubeletExtraArgs map[string]string
+	KubeletExtraArgs []Arg
 
 	// IgnorePreflightErrors provides a slice of pre-flight errors to be ignored when the current node is registered, e.g. 'IsPrivilegedUser,Swap'.
 	// Value 'all' ignores errors from all checks.
@@ -267,9 +266,10 @@ type LocalEtcd struct {
 
 	// ExtraArgs are extra arguments provided to the etcd binary
 	// when run inside a static pod.
-	// A key in this map is the flag name as it appears on the
+	// An argument name in this list is the flag name as it appears on the
-	// command line except without leading dash(es).
+	// command line except without leading dash(es). Extra arguments will override existing
-	ExtraArgs map[string]string
+	// default arguments. Duplicate extra arguments are allowed.
+	ExtraArgs []Arg
 
 	// ExtraEnvs is an extra set of environment variables to pass to the control plane component.
 	// Environment variables passed using ExtraEnvs will override any existing environment variables, or *_proxy environment variables that kubeadm adds by default.
@@ -505,3 +505,9 @@ type ResetConfiguration struct {
 
 // ComponentConfigMap is a map between a group name (as in GVK group) and a ComponentConfig
 type ComponentConfigMap map[string]ComponentConfig
+
+// Arg represents an argument with a name and a value.
+type Arg struct {
+	Name  string
+	Value string
+}

cmd/kubeadm/app/apis/kubeadm/v1beta3/conversion.go

@@ -17,6 +17,8 @@ limitations under the License.
 package v1beta3
 
 import (
+	"sort"
+
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/conversion"
 
@@ -43,19 +45,65 @@ func Convert_v1beta3_InitConfiguration_To_kubeadm_InitConfiguration(in *InitConf
 // Convert_v1beta3_ControlPlaneComponent_To_kubeadm_ControlPlaneComponent is required due to the missing ControlPlaneComponent.ExtraEnvs in v1beta3.
 func Convert_v1beta3_ControlPlaneComponent_To_kubeadm_ControlPlaneComponent(in *ControlPlaneComponent, out *kubeadm.ControlPlaneComponent, s conversion.Scope) error {
 	out.ExtraEnvs = []v1.EnvVar{}
+	out.ExtraArgs = convertToArgs(in.ExtraArgs)
 	return autoConvert_v1beta3_ControlPlaneComponent_To_kubeadm_ControlPlaneComponent(in, out, s)
 }
 
 func Convert_kubeadm_ControlPlaneComponent_To_v1beta3_ControlPlaneComponent(in *kubeadm.ControlPlaneComponent, out *ControlPlaneComponent, s conversion.Scope) error {
+	out.ExtraArgs = convertFromArgs(in.ExtraArgs)
 	return autoConvert_kubeadm_ControlPlaneComponent_To_v1beta3_ControlPlaneComponent(in, out, s)
 }
 
 // Convert_v1beta3_LocalEtcd_To_kubeadm_LocalEtcd is required due to the missing LocalEtcd.ExtraEnvs in v1beta3.
 func Convert_v1beta3_LocalEtcd_To_kubeadm_LocalEtcd(in *LocalEtcd, out *kubeadm.LocalEtcd, s conversion.Scope) error {
 	out.ExtraEnvs = []v1.EnvVar{}
+	out.ExtraArgs = convertToArgs(in.ExtraArgs)
 	return autoConvert_v1beta3_LocalEtcd_To_kubeadm_LocalEtcd(in, out, s)
 }
 
 func Convert_kubeadm_LocalEtcd_To_v1beta3_LocalEtcd(in *kubeadm.LocalEtcd, out *LocalEtcd, s conversion.Scope) error {
+	out.ExtraArgs = convertFromArgs(in.ExtraArgs)
 	return autoConvert_kubeadm_LocalEtcd_To_v1beta3_LocalEtcd(in, out, s)
 }
+
+func Convert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOptions(in *NodeRegistrationOptions, out *kubeadm.NodeRegistrationOptions, s conversion.Scope) error {
+	out.KubeletExtraArgs = convertToArgs(in.KubeletExtraArgs)
+	return autoConvert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOptions(in, out, s)
+}
+
+func Convert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions(in *kubeadm.NodeRegistrationOptions, out *NodeRegistrationOptions, s conversion.Scope) error {
+	out.KubeletExtraArgs = convertFromArgs(in.KubeletExtraArgs)
+	return autoConvert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions(in, out, s)
+}
+
+// convertToArgs takes a argument map and converts it to a slice of arguments.
+// Te resulting argument slice is sorted alpha-numerically.
+func convertToArgs(in map[string]string) []kubeadm.Arg {
+	if in == nil {
+		return nil
+	}
+	args := make([]kubeadm.Arg, 0, len(in))
+	for k, v := range in {
+		args = append(args, kubeadm.Arg{Name: k, Value: v})
+	}
+	sort.Slice(args, func(i, j int) bool {
+		if args[i].Name == args[j].Name {
+			return args[i].Value < args[j].Value
+		}
+		return args[i].Name < args[j].Name
+	})
+	return args
+}
+
+// convertFromArgs takes a slice of arguments and returns an argument map.
+// Duplicate argument keys will be de-duped, where later keys will take precedence.
+func convertFromArgs(in []kubeadm.Arg) map[string]string {
+	if in == nil {
+		return nil
+	}
+	args := make(map[string]string, len(in))
+	for _, arg := range in {
+		args[arg.Name] = arg.Value
+	}
+	return args
+}

cmd/kubeadm/app/apis/kubeadm/v1beta3/conversion_test.go

@@ -0,0 +1,95 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1beta3
+
+import (
+	"reflect"
+	"testing"
+
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+)
+
+func TestConvertToArgs(t *testing.T) {
+	var tests = []struct {
+		name         string
+		args         map[string]string
+		expectedArgs []kubeadmapi.Arg
+	}{
+		{
+			name:         "nil map returns nil args",
+			args:         nil,
+			expectedArgs: nil,
+		},
+		{
+			name: "valid args are parsed (sorted)",
+			args: map[string]string{"c": "d", "a": "b"},
+			expectedArgs: []kubeadmapi.Arg{
+				{Name: "a", Value: "b"},
+				{Name: "c", Value: "d"},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			actual := convertToArgs(tc.args)
+			if !reflect.DeepEqual(tc.expectedArgs, actual) {
+				t.Errorf("expected args: %v\n\t got: %v\n\t", tc.expectedArgs, actual)
+			}
+		})
+	}
+}
+
+func TestConvertFromArgs(t *testing.T) {
+	var tests = []struct {
+		name         string
+		args         []kubeadmapi.Arg
+		expectedArgs map[string]string
+	}{
+		{
+			name:         "nil args return nil map",
+			args:         nil,
+			expectedArgs: nil,
+		},
+		{
+			name: "valid args are parsed",
+			args: []kubeadmapi.Arg{
+				{Name: "a", Value: "b"},
+				{Name: "c", Value: "d"},
+			},
+			expectedArgs: map[string]string{"a": "b", "c": "d"},
+		},
+		{
+			name: "duplicates are dropped",
+			args: []kubeadmapi.Arg{
+				{Name: "a", Value: "b"},
+				{Name: "c", Value: "d1"},
+				{Name: "c", Value: "d2"},
+			},
+			expectedArgs: map[string]string{"a": "b", "c": "d2"},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			actual := convertFromArgs(tc.args)
+			if !reflect.DeepEqual(tc.expectedArgs, actual) {
+				t.Errorf("expected args: %v\n\t got: %v\n\t", tc.expectedArgs, actual)
+			}
+		})
+	}
+}

cmd/kubeadm/app/apis/kubeadm/v1beta3/zz_generated.conversion.go

@@ -174,16 +174,6 @@ func RegisterConversions(s *runtime.Scheme) error {
 	}); err != nil {
 		return err
 	}
-	if err := s.AddGeneratedConversionFunc((*NodeRegistrationOptions)(nil), (*kubeadm.NodeRegistrationOptions)(nil), func(a, b interface{}, scope conversion.Scope) error {
-		return Convert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOptions(a.(*NodeRegistrationOptions), b.(*kubeadm.NodeRegistrationOptions), scope)
-	}); err != nil {
-		return err
-	}
-	if err := s.AddGeneratedConversionFunc((*kubeadm.NodeRegistrationOptions)(nil), (*NodeRegistrationOptions)(nil), func(a, b interface{}, scope conversion.Scope) error {
-		return Convert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions(a.(*kubeadm.NodeRegistrationOptions), b.(*NodeRegistrationOptions), scope)
-	}); err != nil {
-		return err
-	}
 	if err := s.AddGeneratedConversionFunc((*Patches)(nil), (*kubeadm.Patches)(nil), func(a, b interface{}, scope conversion.Scope) error {
 		return Convert_v1beta3_Patches_To_kubeadm_Patches(a.(*Patches), b.(*kubeadm.Patches), scope)
 	}); err != nil {
@@ -214,6 +204,11 @@ func RegisterConversions(s *runtime.Scheme) error {
 	}); err != nil {
 		return err
 	}
+	if err := s.AddConversionFunc((*kubeadm.NodeRegistrationOptions)(nil), (*NodeRegistrationOptions)(nil), func(a, b interface{}, scope conversion.Scope) error {
+		return Convert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions(a.(*kubeadm.NodeRegistrationOptions), b.(*NodeRegistrationOptions), scope)
+	}); err != nil {
+		return err
+	}
 	if err := s.AddConversionFunc((*ControlPlaneComponent)(nil), (*kubeadm.ControlPlaneComponent)(nil), func(a, b interface{}, scope conversion.Scope) error {
 		return Convert_v1beta3_ControlPlaneComponent_To_kubeadm_ControlPlaneComponent(a.(*ControlPlaneComponent), b.(*kubeadm.ControlPlaneComponent), scope)
 	}); err != nil {
@@ -229,6 +224,11 @@ func RegisterConversions(s *runtime.Scheme) error {
 	}); err != nil {
 		return err
 	}
+	if err := s.AddConversionFunc((*NodeRegistrationOptions)(nil), (*kubeadm.NodeRegistrationOptions)(nil), func(a, b interface{}, scope conversion.Scope) error {
+		return Convert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOptions(a.(*NodeRegistrationOptions), b.(*kubeadm.NodeRegistrationOptions), scope)
+	}); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -378,13 +378,13 @@ func Convert_kubeadm_ClusterConfiguration_To_v1beta3_ClusterConfiguration(in *ku
 }
 
 func autoConvert_v1beta3_ControlPlaneComponent_To_kubeadm_ControlPlaneComponent(in *ControlPlaneComponent, out *kubeadm.ControlPlaneComponent, s conversion.Scope) error {
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	// WARNING: in.ExtraArgs requires manual conversion: inconvertible types (map[string]string vs []k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm.Arg)
 	out.ExtraVolumes = *(*[]kubeadm.HostPathMount)(unsafe.Pointer(&in.ExtraVolumes))
 	return nil
 }
 
 func autoConvert_kubeadm_ControlPlaneComponent_To_v1beta3_ControlPlaneComponent(in *kubeadm.ControlPlaneComponent, out *ControlPlaneComponent, s conversion.Scope) error {
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	// WARNING: in.ExtraArgs requires manual conversion: inconvertible types ([]k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm.Arg vs map[string]string)
 	out.ExtraVolumes = *(*[]HostPathMount)(unsafe.Pointer(&in.ExtraVolumes))
 	// WARNING: in.ExtraEnvs requires manual conversion: does not exist in peer-type
 	return nil
@@ -669,7 +669,7 @@ func autoConvert_v1beta3_LocalEtcd_To_kubeadm_LocalEtcd(in *LocalEtcd, out *kube
 		return err
 	}
 	out.DataDir = in.DataDir
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	// WARNING: in.ExtraArgs requires manual conversion: inconvertible types (map[string]string vs []k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm.Arg)
 	out.ServerCertSANs = *(*[]string)(unsafe.Pointer(&in.ServerCertSANs))
 	out.PeerCertSANs = *(*[]string)(unsafe.Pointer(&in.PeerCertSANs))
 	return nil
@@ -680,7 +680,7 @@ func autoConvert_kubeadm_LocalEtcd_To_v1beta3_LocalEtcd(in *kubeadm.LocalEtcd, o
 		return err
 	}
 	out.DataDir = in.DataDir
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	// WARNING: in.ExtraArgs requires manual conversion: inconvertible types ([]k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm.Arg vs map[string]string)
 	// WARNING: in.ExtraEnvs requires manual conversion: does not exist in peer-type
 	out.ServerCertSANs = *(*[]string)(unsafe.Pointer(&in.ServerCertSANs))
 	out.PeerCertSANs = *(*[]string)(unsafe.Pointer(&in.PeerCertSANs))
@@ -715,32 +715,22 @@ func autoConvert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOpti
 	out.Name = in.Name
 	out.CRISocket = in.CRISocket
 	out.Taints = *(*[]corev1.Taint)(unsafe.Pointer(&in.Taints))
-	out.KubeletExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.KubeletExtraArgs))
+	// WARNING: in.KubeletExtraArgs requires manual conversion: inconvertible types (map[string]string vs []k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm.Arg)
 	out.IgnorePreflightErrors = *(*[]string)(unsafe.Pointer(&in.IgnorePreflightErrors))
 	out.ImagePullPolicy = corev1.PullPolicy(in.ImagePullPolicy)
 	return nil
 }
 
-// Convert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOptions is an autogenerated conversion function.
-func Convert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOptions(in *NodeRegistrationOptions, out *kubeadm.NodeRegistrationOptions, s conversion.Scope) error {
-	return autoConvert_v1beta3_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOptions(in, out, s)
-}
-
 func autoConvert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions(in *kubeadm.NodeRegistrationOptions, out *NodeRegistrationOptions, s conversion.Scope) error {
 	out.Name = in.Name
 	out.CRISocket = in.CRISocket
 	out.Taints = *(*[]corev1.Taint)(unsafe.Pointer(&in.Taints))
-	out.KubeletExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.KubeletExtraArgs))
+	// WARNING: in.KubeletExtraArgs requires manual conversion: inconvertible types ([]k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm.Arg vs map[string]string)
 	out.IgnorePreflightErrors = *(*[]string)(unsafe.Pointer(&in.IgnorePreflightErrors))
 	out.ImagePullPolicy = corev1.PullPolicy(in.ImagePullPolicy)
 	return nil
 }
 
-// Convert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions is an autogenerated conversion function.
-func Convert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions(in *kubeadm.NodeRegistrationOptions, out *NodeRegistrationOptions, s conversion.Scope) error {
-	return autoConvert_kubeadm_NodeRegistrationOptions_To_v1beta3_NodeRegistrationOptions(in, out, s)
-}
-
 func autoConvert_v1beta3_Patches_To_kubeadm_Patches(in *Patches, out *kubeadm.Patches, s conversion.Scope) error {
 	out.Directory = in.Directory
 	return nil

cmd/kubeadm/app/apis/kubeadm/v1beta4/doc.go

@@ -26,9 +26,12 @@ limitations under the License.
 //
 //   - TODO https://github.com/kubernetes/kubeadm/issues/2890
 //   - Support custom environment variables in control plane components under `ClusterConfiguration`.
-//     Use `APIServer.ExtraEnvs`, `ControllerManager.ExtraEnvs`, `Scheduler.ExtraEnvs`,  `Etcd.Local.ExtraEnvs`.
+//     Use `APIServer.ExtraEnvs`, `ControllerManager.ExtraEnvs`, `Scheduler.ExtraEnvs`, `Etcd.Local.ExtraEnvs`.
 //   - The ResetConfiguration API type is now supported in v1beta4. Users are able to reset a node by passing a --config file to "kubeadm reset".
 //   - `dry-run` mode in is now configurable in InitConfiguration and JoinConfiguration config files.
+//   - Replace the existing string/string extra argument maps with structured extra arguments that support duplicates.
+//     The change applies to `ClusterConfiguration` - `APIServer.ExtraArgs, `ControllerManager.ExtraArgs`,
+//     `Scheduler.ExtraArgs`, `Etcd.Local.ExtraArgs`. Also to `NodeRegistrationOptions.KubeletExtraArgs`.
 //
 // Migration from old kubeadm config versions
 //

cmd/kubeadm/app/apis/kubeadm/v1beta4/types.go

@@ -144,12 +144,11 @@ type ClusterConfiguration struct {
 // ControlPlaneComponent holds settings common to control plane component of the cluster
 type ControlPlaneComponent struct {
 	// ExtraArgs is an extra set of flags to pass to the control plane component.
-	// A key in this map is the flag name as it appears on the
+	// An argument name in this list is the flag name as it appears on the
-	// command line except without leading dash(es).
+	// command line except without leading dash(es). Extra arguments will override existing
-	// TODO: This is temporary and ideally we would like to switch all components to
+	// default arguments. Duplicate extra arguments are allowed.
-	// use ComponentConfig + ConfigMaps.
 	// +optional
-	ExtraArgs map[string]string `json:"extraArgs,omitempty"`
+	ExtraArgs []Arg `json:"extraArgs,omitempty"`
 
 	// ExtraVolumes is an extra set of host volumes, mounted to the control plane component.
 	// +optional
@@ -232,10 +231,10 @@ type NodeRegistrationOptions struct {
 	// KubeletExtraArgs passes through extra arguments to the kubelet. The arguments here are passed to the kubelet command line via the environment file
 	// kubeadm writes at runtime for the kubelet to source. This overrides the generic base-level configuration in the kubelet-config ConfigMap
 	// Flags have higher priority when parsing. These values are local and specific to the node kubeadm is executing on.
-	// A key in this map is the flag name as it appears on the
+	// An argument name in this list is the flag name as it appears on the command line except without leading dash(es).
-	// command line except without leading dash(es).
+	// Extra arguments will override existing default arguments. Duplicate extra arguments are allowed.
 	// +optional
-	KubeletExtraArgs map[string]string `json:"kubeletExtraArgs,omitempty"`
+	KubeletExtraArgs []Arg `json:"kubeletExtraArgs,omitempty"`
 
 	// IgnorePreflightErrors provides a slice of pre-flight errors to be ignored when the current node is registered, e.g. 'IsPrivilegedUser,Swap'.
 	// Value 'all' ignores errors from all checks.
@@ -287,10 +286,11 @@ type LocalEtcd struct {
 
 	// ExtraArgs are extra arguments provided to the etcd binary
 	// when run inside a static pod.
-	// A key in this map is the flag name as it appears on the
+	// An argument name in this list is the flag name as it appears on the
-	// command line except without leading dash(es).
+	// command line except without leading dash(es). Extra arguments will override existing
+	// default arguments. Duplicate extra arguments are allowed.
 	// +optional
-	ExtraArgs map[string]string `json:"extraArgs,omitempty"`
+	ExtraArgs []Arg `json:"extraArgs,omitempty"`
 
 	// ExtraEnvs is an extra set of environment variables to pass to the control plane component.
 	// Environment variables passed using ExtraEnvs will override any existing environment variables, or *_proxy environment variables that kubeadm adds by default.
@@ -500,3 +500,9 @@ type ResetConfiguration struct {
 	// +optional
 	SkipPhases []string `json:"skipPhases,omitempty"`
 }
+
+// Arg represents an argument with a name and a value.
+type Arg struct {
+	Name  string `json:"name"`
+	Value string `json:"value"`
+}

cmd/kubeadm/app/apis/kubeadm/v1beta4/zz_generated.conversion.go

@@ -59,6 +59,16 @@ func RegisterConversions(s *runtime.Scheme) error {
 	}); err != nil {
 		return err
 	}
+	if err := s.AddGeneratedConversionFunc((*Arg)(nil), (*kubeadm.Arg)(nil), func(a, b interface{}, scope conversion.Scope) error {
+		return Convert_v1beta4_Arg_To_kubeadm_Arg(a.(*Arg), b.(*kubeadm.Arg), scope)
+	}); err != nil {
+		return err
+	}
+	if err := s.AddGeneratedConversionFunc((*kubeadm.Arg)(nil), (*Arg)(nil), func(a, b interface{}, scope conversion.Scope) error {
+		return Convert_kubeadm_Arg_To_v1beta4_Arg(a.(*kubeadm.Arg), b.(*Arg), scope)
+	}); err != nil {
+		return err
+	}
 	if err := s.AddGeneratedConversionFunc((*BootstrapTokenDiscovery)(nil), (*kubeadm.BootstrapTokenDiscovery)(nil), func(a, b interface{}, scope conversion.Scope) error {
 		return Convert_v1beta4_BootstrapTokenDiscovery_To_kubeadm_BootstrapTokenDiscovery(a.(*BootstrapTokenDiscovery), b.(*kubeadm.BootstrapTokenDiscovery), scope)
 	}); err != nil {
@@ -292,6 +302,28 @@ func Convert_kubeadm_APIServer_To_v1beta4_APIServer(in *kubeadm.APIServer, out *
 	return autoConvert_kubeadm_APIServer_To_v1beta4_APIServer(in, out, s)
 }
 
+func autoConvert_v1beta4_Arg_To_kubeadm_Arg(in *Arg, out *kubeadm.Arg, s conversion.Scope) error {
+	out.Name = in.Name
+	out.Value = in.Value
+	return nil
+}
+
+// Convert_v1beta4_Arg_To_kubeadm_Arg is an autogenerated conversion function.
+func Convert_v1beta4_Arg_To_kubeadm_Arg(in *Arg, out *kubeadm.Arg, s conversion.Scope) error {
+	return autoConvert_v1beta4_Arg_To_kubeadm_Arg(in, out, s)
+}
+
+func autoConvert_kubeadm_Arg_To_v1beta4_Arg(in *kubeadm.Arg, out *Arg, s conversion.Scope) error {
+	out.Name = in.Name
+	out.Value = in.Value
+	return nil
+}
+
+// Convert_kubeadm_Arg_To_v1beta4_Arg is an autogenerated conversion function.
+func Convert_kubeadm_Arg_To_v1beta4_Arg(in *kubeadm.Arg, out *Arg, s conversion.Scope) error {
+	return autoConvert_kubeadm_Arg_To_v1beta4_Arg(in, out, s)
+}
+
 func autoConvert_v1beta4_BootstrapTokenDiscovery_To_kubeadm_BootstrapTokenDiscovery(in *BootstrapTokenDiscovery, out *kubeadm.BootstrapTokenDiscovery, s conversion.Scope) error {
 	out.Token = in.Token
 	out.APIServerEndpoint = in.APIServerEndpoint
@@ -388,7 +420,7 @@ func Convert_kubeadm_ClusterConfiguration_To_v1beta4_ClusterConfiguration(in *ku
 }
 
 func autoConvert_v1beta4_ControlPlaneComponent_To_kubeadm_ControlPlaneComponent(in *ControlPlaneComponent, out *kubeadm.ControlPlaneComponent, s conversion.Scope) error {
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	out.ExtraArgs = *(*[]kubeadm.Arg)(unsafe.Pointer(&in.ExtraArgs))
 	out.ExtraVolumes = *(*[]kubeadm.HostPathMount)(unsafe.Pointer(&in.ExtraVolumes))
 	out.ExtraEnvs = *(*[]corev1.EnvVar)(unsafe.Pointer(&in.ExtraEnvs))
 	return nil
@@ -400,7 +432,7 @@ func Convert_v1beta4_ControlPlaneComponent_To_kubeadm_ControlPlaneComponent(in *
 }
 
 func autoConvert_kubeadm_ControlPlaneComponent_To_v1beta4_ControlPlaneComponent(in *kubeadm.ControlPlaneComponent, out *ControlPlaneComponent, s conversion.Scope) error {
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	out.ExtraArgs = *(*[]Arg)(unsafe.Pointer(&in.ExtraArgs))
 	out.ExtraVolumes = *(*[]HostPathMount)(unsafe.Pointer(&in.ExtraVolumes))
 	out.ExtraEnvs = *(*[]corev1.EnvVar)(unsafe.Pointer(&in.ExtraEnvs))
 	return nil
@@ -681,7 +713,7 @@ func autoConvert_v1beta4_LocalEtcd_To_kubeadm_LocalEtcd(in *LocalEtcd, out *kube
 		return err
 	}
 	out.DataDir = in.DataDir
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	out.ExtraArgs = *(*[]kubeadm.Arg)(unsafe.Pointer(&in.ExtraArgs))
 	out.ExtraEnvs = *(*[]corev1.EnvVar)(unsafe.Pointer(&in.ExtraEnvs))
 	out.ServerCertSANs = *(*[]string)(unsafe.Pointer(&in.ServerCertSANs))
 	out.PeerCertSANs = *(*[]string)(unsafe.Pointer(&in.PeerCertSANs))
@@ -698,7 +730,7 @@ func autoConvert_kubeadm_LocalEtcd_To_v1beta4_LocalEtcd(in *kubeadm.LocalEtcd, o
 		return err
 	}
 	out.DataDir = in.DataDir
-	out.ExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.ExtraArgs))
+	out.ExtraArgs = *(*[]Arg)(unsafe.Pointer(&in.ExtraArgs))
 	out.ExtraEnvs = *(*[]corev1.EnvVar)(unsafe.Pointer(&in.ExtraEnvs))
 	out.ServerCertSANs = *(*[]string)(unsafe.Pointer(&in.ServerCertSANs))
 	out.PeerCertSANs = *(*[]string)(unsafe.Pointer(&in.PeerCertSANs))
@@ -738,7 +770,7 @@ func autoConvert_v1beta4_NodeRegistrationOptions_To_kubeadm_NodeRegistrationOpti
 	out.Name = in.Name
 	out.CRISocket = in.CRISocket
 	out.Taints = *(*[]corev1.Taint)(unsafe.Pointer(&in.Taints))
-	out.KubeletExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.KubeletExtraArgs))
+	out.KubeletExtraArgs = *(*[]kubeadm.Arg)(unsafe.Pointer(&in.KubeletExtraArgs))
 	out.IgnorePreflightErrors = *(*[]string)(unsafe.Pointer(&in.IgnorePreflightErrors))
 	out.ImagePullPolicy = corev1.PullPolicy(in.ImagePullPolicy)
 	return nil
@@ -753,7 +785,7 @@ func autoConvert_kubeadm_NodeRegistrationOptions_To_v1beta4_NodeRegistrationOpti
 	out.Name = in.Name
 	out.CRISocket = in.CRISocket
 	out.Taints = *(*[]corev1.Taint)(unsafe.Pointer(&in.Taints))
-	out.KubeletExtraArgs = *(*map[string]string)(unsafe.Pointer(&in.KubeletExtraArgs))
+	out.KubeletExtraArgs = *(*[]Arg)(unsafe.Pointer(&in.KubeletExtraArgs))
 	out.IgnorePreflightErrors = *(*[]string)(unsafe.Pointer(&in.IgnorePreflightErrors))
 	out.ImagePullPolicy = corev1.PullPolicy(in.ImagePullPolicy)
 	return nil

cmd/kubeadm/app/apis/kubeadm/v1beta4/zz_generated.deepcopy.go

@@ -71,6 +71,22 @@ func (in *APIServer) DeepCopy() *APIServer {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *Arg) DeepCopyInto(out *Arg) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new Arg.
+func (in *Arg) DeepCopy() *Arg {
+	if in == nil {
+		return nil
+	}
+	out := new(Arg)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *BootstrapTokenDiscovery) DeepCopyInto(out *BootstrapTokenDiscovery) {
 	*out = *in
@@ -135,10 +151,8 @@ func (in *ControlPlaneComponent) DeepCopyInto(out *ControlPlaneComponent) {
 	*out = *in
 	if in.ExtraArgs != nil {
 		in, out := &in.ExtraArgs, &out.ExtraArgs
-		*out = make(map[string]string, len(*in))
+		*out = make([]Arg, len(*in))
-		for key, val := range *in {
+		copy(*out, *in)
-			(*out)[key] = val
-		}
 	}
 	if in.ExtraVolumes != nil {
 		in, out := &in.ExtraVolumes, &out.ExtraVolumes
@@ -417,10 +431,8 @@ func (in *LocalEtcd) DeepCopyInto(out *LocalEtcd) {
 	out.ImageMeta = in.ImageMeta
 	if in.ExtraArgs != nil {
 		in, out := &in.ExtraArgs, &out.ExtraArgs
-		*out = make(map[string]string, len(*in))
+		*out = make([]Arg, len(*in))
-		for key, val := range *in {
+		copy(*out, *in)
-			(*out)[key] = val
-		}
 	}
 	if in.ExtraEnvs != nil {
 		in, out := &in.ExtraEnvs, &out.ExtraEnvs
@@ -480,10 +492,8 @@ func (in *NodeRegistrationOptions) DeepCopyInto(out *NodeRegistrationOptions) {
 	}
 	if in.KubeletExtraArgs != nil {
 		in, out := &in.KubeletExtraArgs, &out.KubeletExtraArgs
-		*out = make(map[string]string, len(*in))
+		*out = make([]Arg, len(*in))
-		for key, val := range *in {
+		copy(*out, *in)
-			(*out)[key] = val
-		}
 	}
 	if in.IgnorePreflightErrors != nil {
 		in, out := &in.IgnorePreflightErrors, &out.IgnorePreflightErrors

cmd/kubeadm/app/apis/kubeadm/zz_generated.deepcopy.go

@@ -71,6 +71,22 @@ func (in *APIServer) DeepCopy() *APIServer {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *Arg) DeepCopyInto(out *Arg) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new Arg.
+func (in *Arg) DeepCopy() *Arg {
+	if in == nil {
+		return nil
+	}
+	out := new(Arg)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *BootstrapTokenDiscovery) DeepCopyInto(out *BootstrapTokenDiscovery) {
 	*out = *in
@@ -164,10 +180,8 @@ func (in *ControlPlaneComponent) DeepCopyInto(out *ControlPlaneComponent) {
 	*out = *in
 	if in.ExtraArgs != nil {
 		in, out := &in.ExtraArgs, &out.ExtraArgs
-		*out = make(map[string]string, len(*in))
+		*out = make([]Arg, len(*in))
-		for key, val := range *in {
+		copy(*out, *in)
-			(*out)[key] = val
-		}
 	}
 	if in.ExtraVolumes != nil {
 		in, out := &in.ExtraVolumes, &out.ExtraVolumes
@@ -447,10 +461,8 @@ func (in *LocalEtcd) DeepCopyInto(out *LocalEtcd) {
 	out.ImageMeta = in.ImageMeta
 	if in.ExtraArgs != nil {
 		in, out := &in.ExtraArgs, &out.ExtraArgs
-		*out = make(map[string]string, len(*in))
+		*out = make([]Arg, len(*in))
-		for key, val := range *in {
+		copy(*out, *in)
-			(*out)[key] = val
-		}
 	}
 	if in.ExtraEnvs != nil {
 		in, out := &in.ExtraEnvs, &out.ExtraEnvs
@@ -510,10 +522,8 @@ func (in *NodeRegistrationOptions) DeepCopyInto(out *NodeRegistrationOptions) {
 	}
 	if in.KubeletExtraArgs != nil {
 		in, out := &in.KubeletExtraArgs, &out.KubeletExtraArgs
-		*out = make(map[string]string, len(*in))
+		*out = make([]Arg, len(*in))
-		for key, val := range *in {
+		copy(*out, *in)
-			(*out)[key] = val
-		}
 	}
 	if in.IgnorePreflightErrors != nil {
 		in, out := &in.IgnorePreflightErrors, &out.IgnorePreflightErrors