kubeadm: statically default ImagePullPolicy in v1beta3

Instead of dynamically defaulting NodeRegistration.ImagePullPolicy,
which is common when doing defaulting depending on host state - e.g.
hostname, statically default it in v1beta3/defaults.go.

- Remove defaulting in checks.go
- Add one more unit test in checks_test.go
- Adapt v1beta2 conversion and fuzzer / round tripping tests

This also results in the default being visible when calling:
"kubeadm config print ...".

cmd/kubeadm/app/apis/kubeadm/fuzzer/fuzzer.go

@@ -21,6 +21,7 @@ import (
 	"k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 
+	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	runtimeserializer "k8s.io/apimachinery/pkg/runtime/serializer"
 
@@ -60,7 +61,7 @@ func fuzzInitConfiguration(obj *kubeadm.InitConfiguration, c fuzz.Continue) {
 		},
 	}
 	obj.SkipPhases = nil
-	obj.NodeRegistration.ImagePullPolicy = ""
+	obj.NodeRegistration.ImagePullPolicy = corev1.PullIfNotPresent
 	obj.Patches = nil
 }
 
@@ -123,7 +124,7 @@ func fuzzJoinConfiguration(obj *kubeadm.JoinConfiguration, c fuzz.Continue) {
 		Timeout:           &metav1.Duration{Duration: 1234},
 	}
 	obj.SkipPhases = nil
-	obj.NodeRegistration.ImagePullPolicy = ""
+	obj.NodeRegistration.ImagePullPolicy = corev1.PullIfNotPresent
 	obj.Patches = nil
 }
 

cmd/kubeadm/app/apis/kubeadm/v1beta2/conversion.go

@@ -19,6 +19,7 @@ package v1beta2
 import (
 	kubeadm "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 
+	corev1 "k8s.io/api/core/v1"
 	conversion "k8s.io/apimachinery/pkg/conversion"
 )
 
@@ -31,6 +32,9 @@ func Convert_v1beta2_InitConfiguration_To_kubeadm_InitConfiguration(in *InitConf
 	if err != nil {
 		return err
 	}
+	// Needed for round-tripping since this field is defaulted in v1beta3
+	out.NodeRegistration.ImagePullPolicy = corev1.PullIfNotPresent
+
 	return Convert_v1beta2_ClusterConfiguration_To_kubeadm_ClusterConfiguration(&ClusterConfiguration{}, &out.ClusterConfiguration, s)
 }
 
@@ -49,3 +53,14 @@ func Convert_kubeadm_JoinConfiguration_To_v1beta2_JoinConfiguration(in *kubeadm.
 func Convert_kubeadm_NodeRegistrationOptions_To_v1beta2_NodeRegistrationOptions(in *kubeadm.NodeRegistrationOptions, out *NodeRegistrationOptions, s conversion.Scope) error {
 	return autoConvert_kubeadm_NodeRegistrationOptions_To_v1beta2_NodeRegistrationOptions(in, out, s)
 }
+
+// Convert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration is required since v1beta2 does not have NodeRegistrationOption.ImagePullPolicy
+// and to make round-tripping happy.
+func Convert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration(in *JoinConfiguration, out *kubeadm.JoinConfiguration, s conversion.Scope) error {
+	err := autoConvert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration(in, out, s)
+	if err != nil {
+		return err
+	}
+	out.NodeRegistration.ImagePullPolicy = corev1.PullIfNotPresent
+	return nil
+}

cmd/kubeadm/app/apis/kubeadm/v1beta2/zz_generated.conversion.go

@@ -153,11 +153,6 @@ func RegisterConversions(s *runtime.Scheme) error {
 	}); err != nil {
 		return err
 	}
-	if err := s.AddGeneratedConversionFunc((*JoinConfiguration)(nil), (*kubeadm.JoinConfiguration)(nil), func(a, b interface{}, scope conversion.Scope) error {
-		return Convert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration(a.(*JoinConfiguration), b.(*kubeadm.JoinConfiguration), scope)
-	}); err != nil {
-		return err
-	}
 	if err := s.AddGeneratedConversionFunc((*JoinControlPlane)(nil), (*kubeadm.JoinControlPlane)(nil), func(a, b interface{}, scope conversion.Scope) error {
 		return Convert_v1beta2_JoinControlPlane_To_kubeadm_JoinControlPlane(a.(*JoinControlPlane), b.(*kubeadm.JoinControlPlane), scope)
 	}); err != nil {
@@ -218,6 +213,11 @@ func RegisterConversions(s *runtime.Scheme) error {
 	}); err != nil {
 		return err
 	}
+	if err := s.AddConversionFunc((*JoinConfiguration)(nil), (*kubeadm.JoinConfiguration)(nil), func(a, b interface{}, scope conversion.Scope) error {
+		return Convert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration(a.(*JoinConfiguration), b.(*kubeadm.JoinConfiguration), scope)
+	}); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -592,11 +592,6 @@ func autoConvert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration(in *Join
 	return nil
 }
 
-// Convert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration is an autogenerated conversion function.
-func Convert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration(in *JoinConfiguration, out *kubeadm.JoinConfiguration, s conversion.Scope) error {
-	return autoConvert_v1beta2_JoinConfiguration_To_kubeadm_JoinConfiguration(in, out, s)
-}
-
 func autoConvert_kubeadm_JoinConfiguration_To_v1beta2_JoinConfiguration(in *kubeadm.JoinConfiguration, out *JoinConfiguration, s conversion.Scope) error {
 	if err := Convert_kubeadm_NodeRegistrationOptions_To_v1beta2_NodeRegistrationOptions(&in.NodeRegistration, &out.NodeRegistration, s); err != nil {
 		return err

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

@@ -20,11 +20,12 @@ import (
 	"net/url"
 	"time"
 
+	bootstraptokenv1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/bootstraptoken/v1"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 
+	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
-	bootstraptokenv1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/bootstraptoken/v1"
 )
 
 const (
@@ -55,6 +56,9 @@ const (
 	DefaultProxyBindAddressv6 = "::"
 	// DefaultDiscoveryTimeout specifies the default discovery timeout for kubeadm (used unless one is specified in the JoinConfiguration)
 	DefaultDiscoveryTimeout = 5 * time.Minute
+
+	// DefaultImagePullPolicy is the default image pull policy in kubeadm
+	DefaultImagePullPolicy = corev1.PullIfNotPresent
 )
 
 var (
@@ -71,6 +75,7 @@ func addDefaultingFuncs(scheme *runtime.Scheme) error {
 func SetDefaults_InitConfiguration(obj *InitConfiguration) {
 	SetDefaults_BootstrapTokens(obj)
 	SetDefaults_APIEndpoint(&obj.LocalAPIEndpoint)
+	SetDefaults_NodeRegistration(&obj.NodeRegistration)
 }
 
 // SetDefaults_ClusterConfiguration assigns default values for the ClusterConfiguration
@@ -132,6 +137,7 @@ func SetDefaults_JoinConfiguration(obj *JoinConfiguration) {
 
 	SetDefaults_JoinControlPlane(obj.ControlPlane)
 	SetDefaults_Discovery(&obj.Discovery)
+	SetDefaults_NodeRegistration(&obj.NodeRegistration)
 }
 
 func SetDefaults_JoinControlPlane(obj *JoinControlPlane) {
@@ -206,3 +212,10 @@ func SetDefaults_APIEndpoint(obj *APIEndpoint) {
 		obj.BindPort = DefaultAPIBindPort
 	}
 }
+
+// SetDefaults_NodeRegistration sets the defaults for the NodeRegistrationOptions object
+func SetDefaults_NodeRegistration(obj *NodeRegistrationOptions) {
+	if len(obj.ImagePullPolicy) == 0 {
+		obj.ImagePullPolicy = DefaultImagePullPolicy
+	}
+}

cmd/kubeadm/app/preflight/checks.go

@@ -835,9 +835,6 @@ func (ImagePullCheck) Name() string {
 // Check pulls images required by kubeadm. This is a mutating check
 func (ipc ImagePullCheck) Check() (warnings, errorList []error) {
 	policy := ipc.imagePullPolicy
-	if len(policy) == 0 {
-		policy = v1.PullIfNotPresent // Default behavior if the policy is unset
-	}
 	klog.V(1).Infof("using image pull policy: %s", policy)
 	for _, image := range ipc.imageList {
 		switch policy {

cmd/kubeadm/app/preflight/checks_test.go

@@ -31,6 +31,7 @@ import (
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	utilruntime "k8s.io/kubernetes/cmd/kubeadm/app/util/runtime"
 
+	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/utils/exec"
 	fakeexec "k8s.io/utils/exec/testing"
@@ -923,7 +924,7 @@ func TestImagePullCheck(t *testing.T) {
 	check := ImagePullCheck{
 		runtime:         containerRuntime,
 		imageList:       []string{"img1", "img2", "img3"},
-		imagePullPolicy: "", // should be defaulted to v1.PullIfNotPresent
+		imagePullPolicy: corev1.PullIfNotPresent,
 	}
 	warnings, errors := check.Check()
 	if len(warnings) != 0 {
@@ -940,6 +941,17 @@ func TestImagePullCheck(t *testing.T) {
 	if len(errors) != 2 {
 		t.Fatalf("expected 2 errors but got %d: %q", len(errors), errors)
 	}
+
+	// Test with unknown policy
+	check = ImagePullCheck{
+		runtime:         containerRuntime,
+		imageList:       []string{"img1", "img2", "img3"},
+		imagePullPolicy: "",
+	}
+	_, errors = check.Check()
+	if len(errors) != 1 {
+		t.Fatalf("expected 1 error but got %d: %q", len(errors), errors)
+	}
 }
 
 func TestNumCPUCheck(t *testing.T) {