kubeadm/phases: use common interfaces for init and join phases

The custom sub-set interfaces in init/join phases as a pattern
have isolation benefits - e.g. when a consumer imports these
but we don't want them to be able to call all methods from
the original object that satisfies a complete interface.

On the other hand these sub-set interfaces under phases/init
and phases/join are private.

Expose a couple of new common interfaces:
- InitData from phases/init/data.go
- JoinData from phases/join/data.go

Use these interfaces in init/join phases accordingly instead
of the sub-set interfaces.

Use compile-time type assertion to verify that these
interfaces can be satisfied by init.go's initData and
join.go's joinData.

Add NO-OP objects called testInitData and joinInitData
that can be used for unit testing if embedded.

cmd/kubeadm/app/cmd/init.go

@@ -87,7 +87,10 @@ type initOptions struct {
 	uploadCerts           bool
 }
 
-// initData defines all the runtime information used when running the kubeadm init workflow;
+// compile-time assert that the local data object satisfies the phases data interface.
+var _ phases.InitData = &initData{}
+
+// initData defines all the runtime information used when running the kubeadm init worklow;
 // this data is shared across all the phases that are included in the workflow.
 type initData struct {
 	cfg                   *kubeadmapi.InitConfiguration

cmd/kubeadm/app/cmd/join.go

@@ -129,6 +129,9 @@ type joinOptions struct {
 	externalcfg           *kubeadmapiv1beta1.JoinConfiguration
 }
 
+// compile-time assert that the local data object satisfies the phases data interface.
+var _ phases.JoinData = &joinData{}
+
 // joinData defines all the runtime information used when running the kubeadm join worklow;
 // this data is shared across all the phases that are included in the workflow.
 type joinData struct {

cmd/kubeadm/app/cmd/phases/init/BUILD

@@ -7,6 +7,7 @@ go_library(
         "bootstraptoken.go",
         "certs.go",
         "controlplane.go",
+        "data.go",
         "etcd.go",
         "kubeconfig.go",
         "kubelet.go",
@@ -58,7 +59,10 @@ go_library(
 
 go_test(
     name = "go_default_test",
-    srcs = ["certs_test.go"],
+    srcs = [
+        "certs_test.go",
+        "data_test.go",
+    ],
     embed = [":go_default_library"],
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
@@ -67,6 +71,8 @@ go_test(
         "//cmd/kubeadm/app/util/certs:go_default_library",
         "//cmd/kubeadm/app/util/pkiutil:go_default_library",
         "//cmd/kubeadm/test:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/github.com/spf13/cobra:go_default_library",
     ],
 )

cmd/kubeadm/app/cmd/phases/init/addons.go

@@ -40,11 +40,6 @@ var (
 		`)
 )
 
-type addonData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	Client() (clientset.Interface, error)
-}
-
 // NewAddonPhase returns the addon Cobra command
 func NewAddonPhase() workflow.Phase {
 	return workflow.Phase{
@@ -76,8 +71,8 @@ func NewAddonPhase() workflow.Phase {
 	}
 }
 
-func getAddonData(c workflow.RunData) (*kubeadmapi.InitConfiguration, clientset.Interface, error) {
-	data, ok := c.(addonData)
+func getInitData(c workflow.RunData) (*kubeadmapi.InitConfiguration, clientset.Interface, error) {
+	data, ok := c.(InitData)
 	if !ok {
 		return nil, nil, errors.New("addon phase invoked with an invalid data struct")
 	}
@@ -91,7 +86,7 @@ func getAddonData(c workflow.RunData) (*kubeadmapi.InitConfiguration, clientset.
 
 // runCoreDNSAddon installs CoreDNS addon to a Kubernetes cluster
 func runCoreDNSAddon(c workflow.RunData) error {
-	cfg, client, err := getAddonData(c)
+	cfg, client, err := getInitData(c)
 	if err != nil {
 		return err
 	}
@@ -100,7 +95,7 @@ func runCoreDNSAddon(c workflow.RunData) error {
 
 // runKubeProxyAddon installs KubeProxy addon to a Kubernetes cluster
 func runKubeProxyAddon(c workflow.RunData) error {
-	cfg, client, err := getAddonData(c)
+	cfg, client, err := getInitData(c)
 	if err != nil {
 		return err
 	}

cmd/kubeadm/app/cmd/phases/init/bootstraptoken.go

@@ -21,8 +21,6 @@ import (
 
 	"github.com/pkg/errors"
 
-	clientset "k8s.io/client-go/kubernetes"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	clusterinfophase "k8s.io/kubernetes/cmd/kubeadm/app/phases/bootstraptoken/clusterinfo"
@@ -46,14 +44,6 @@ var (
 		`)
 )
 
-type bootstrapTokenData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	Client() (clientset.Interface, error)
-	KubeConfigPath() string
-	SkipTokenPrint() bool
-	Tokens() []string
-}
-
 // NewBootstrapTokenPhase returns the phase to bootstrapToken
 func NewBootstrapTokenPhase() workflow.Phase {
 	return workflow.Phase{
@@ -72,7 +62,7 @@ func NewBootstrapTokenPhase() workflow.Phase {
 }
 
 func runBootstrapToken(c workflow.RunData) error {
-	data, ok := c.(bootstrapTokenData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("bootstrap-token phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/init/certs.go

@@ -54,16 +54,6 @@ var (
 	csrDir  string
 )
 
-// certsData defines the behavior that a runtime data struct passed to the certs phase should
-// have. Please note that we are using an interface in order to make this phase reusable in different workflows
-// (and thus with different runtime data struct, all of them requested to be compliant to this interface)
-type certsData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	ExternalCA() bool
-	CertificateDir() string
-	CertificateWriteDir() string
-}
-
 // NewCertsPhase returns the phase for the certs
 func NewCertsPhase() workflow.Phase {
 	return workflow.Phase{
@@ -193,7 +183,7 @@ func getSANDescription(certSpec *certsphase.KubeadmCert) string {
 }
 
 func runCertsSa(c workflow.RunData) error {
-	data, ok := c.(certsData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("certs phase invoked with an invalid data struct")
 	}
@@ -209,7 +199,7 @@ func runCertsSa(c workflow.RunData) error {
 }
 
 func runCerts(c workflow.RunData) error {
-	data, ok := c.(certsData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("certs phase invoked with an invalid data struct")
 	}
@@ -220,7 +210,7 @@ func runCerts(c workflow.RunData) error {
 
 func runCAPhase(ca *certsphase.KubeadmCert) func(c workflow.RunData) error {
 	return func(c workflow.RunData) error {
-		data, ok := c.(certsData)
+		data, ok := c.(InitData)
 		if !ok {
 			return errors.New("certs phase invoked with an invalid data struct")
 		}
@@ -252,7 +242,7 @@ func runCAPhase(ca *certsphase.KubeadmCert) func(c workflow.RunData) error {
 
 func runCertPhase(cert *certsphase.KubeadmCert, caCert *certsphase.KubeadmCert) func(c workflow.RunData) error {
 	return func(c workflow.RunData) error {
-		data, ok := c.(certsData)
+		data, ok := c.(InitData)
 		if !ok {
 			return errors.New("certs phase invoked with an invalid data struct")
 		}

cmd/kubeadm/app/cmd/phases/init/certs_test.go

@@ -30,6 +30,7 @@ import (
 )
 
 type testCertsData struct {
+	testInitData
 	cfg *kubeadmapi.InitConfiguration
 }
 

cmd/kubeadm/app/cmd/phases/init/controlplane.go

@@ -21,7 +21,6 @@ import (
 
 	"github.com/pkg/errors"
 
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -59,12 +58,6 @@ var (
 	}
 )
 
-type controlPlaneData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	KubeConfigDir() string
-	ManifestDir() string
-}
-
 func getPhaseDescription(component string) string {
 	return fmt.Sprintf("Generates the %s static Pod manifest", component)
 }
@@ -133,7 +126,7 @@ func getControlPlanePhaseFlags(name string) []string {
 }
 
 func runControlPlanePhase(c workflow.RunData) error {
-	data, ok := c.(controlPlaneData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("control-plane phase invoked with an invalid data struct")
 	}
@@ -144,7 +137,7 @@ func runControlPlanePhase(c workflow.RunData) error {
 
 func runControlPlaneSubphase(component string) func(c workflow.RunData) error {
 	return func(c workflow.RunData) error {
-		data, ok := c.(controlPlaneData)
+		data, ok := c.(InitData)
 		if !ok {
 			return errors.New("control-plane phase invoked with an invalid data struct")
 		}

cmd/kubeadm/app/cmd/phases/init/data.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2019 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 phases
+
+import (
+	"io"
+
+	"k8s.io/apimachinery/pkg/util/sets"
+	clientset "k8s.io/client-go/kubernetes"
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+)
+
+// InitData is the interface to use for init phases.
+// The "initData" type from "cmd/init.go" must satisfy this interface.
+type InitData interface {
+	UploadCerts() bool
+	CertificateKey() string
+	SetCertificateKey(key string)
+	Cfg() *kubeadmapi.InitConfiguration
+	DryRun() bool
+	SkipTokenPrint() bool
+	IgnorePreflightErrors() sets.String
+	CertificateWriteDir() string
+	CertificateDir() string
+	KubeConfigDir() string
+	KubeConfigPath() string
+	ManifestDir() string
+	KubeletDir() string
+	ExternalCA() bool
+	OutputWriter() io.Writer
+	Client() (clientset.Interface, error)
+	Tokens() []string
+}

cmd/kubeadm/app/cmd/phases/init/data_test.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2019 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 phases
+
+import (
+	"io"
+
+	"k8s.io/apimachinery/pkg/util/sets"
+	clientset "k8s.io/client-go/kubernetes"
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+)
+
+// a package local type for testing purposes.
+type testInitData struct{}
+
+// testInitData must satisfy InitData.
+var _ InitData = &testInitData{}
+
+func (t *testInitData) UploadCerts() bool                    { return false }
+func (t *testInitData) CertificateKey() string               { return "" }
+func (t *testInitData) SetCertificateKey(key string)         {}
+func (t *testInitData) Cfg() *kubeadmapi.InitConfiguration   { return nil }
+func (t *testInitData) DryRun() bool                         { return false }
+func (t *testInitData) SkipTokenPrint() bool                 { return false }
+func (t *testInitData) IgnorePreflightErrors() sets.String   { return nil }
+func (t *testInitData) CertificateWriteDir() string          { return "" }
+func (t *testInitData) CertificateDir() string               { return "" }
+func (t *testInitData) KubeConfigDir() string                { return "" }
+func (t *testInitData) KubeConfigPath() string               { return "" }
+func (t *testInitData) ManifestDir() string                  { return "" }
+func (t *testInitData) KubeletDir() string                   { return "" }
+func (t *testInitData) ExternalCA() bool                     { return false }
+func (t *testInitData) OutputWriter() io.Writer              { return nil }
+func (t *testInitData) Client() (clientset.Interface, error) { return nil, nil }
+func (t *testInitData) Tokens() []string                     { return nil }

cmd/kubeadm/app/cmd/phases/init/etcd.go

@@ -22,7 +22,6 @@ import (
 
 	"github.com/pkg/errors"
 	"k8s.io/klog"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -42,12 +41,6 @@ var (
 		`)
 )
 
-type etcdData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	DryRun() bool
-	ManifestDir() string
-}
-
 // NewEtcdPhase creates a kubeadm workflow phase that implements handling of etcd.
 func NewEtcdPhase() workflow.Phase {
 	phase := workflow.Phase{
@@ -83,7 +76,7 @@ func getEtcdPhaseFlags() []string {
 
 func runEtcdPhaseLocal() func(c workflow.RunData) error {
 	return func(c workflow.RunData) error {
-		data, ok := c.(etcdData)
+		data, ok := c.(InitData)
 		if !ok {
 			return errors.New("etcd phase invoked with an invalid data struct")
 		}

cmd/kubeadm/app/cmd/phases/init/kubeconfig.go

@@ -20,7 +20,6 @@ import (
 	"fmt"
 
 	"github.com/pkg/errors"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -62,17 +61,6 @@ var (
 	}
 )
 
-// kubeConfigData defines the behavior that a runtime data struct passed to the kubeconfig phase
-// should have. Please note that we are using an interface in order to make this phase reusable in different workflows
-// (and thus with different runtime data struct, all of them requested to be compliant to this interface)
-type kubeConfigData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	ExternalCA() bool
-	CertificateDir() string
-	CertificateWriteDir() string
-	KubeConfigDir() string
-}
-
 // NewKubeConfigPhase creates a kubeadm workflow phase that creates all kubeconfig files necessary to establish the control plane and the admin kubeconfig file.
 func NewKubeConfigPhase() workflow.Phase {
 	return workflow.Phase{
@@ -123,7 +111,7 @@ func getKubeConfigPhaseFlags(name string) []string {
 }
 
 func runKubeConfig(c workflow.RunData) error {
-	data, ok := c.(kubeConfigData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("kubeconfig phase invoked with an invalid data struct")
 	}
@@ -135,7 +123,7 @@ func runKubeConfig(c workflow.RunData) error {
 // runKubeConfigFile executes kubeconfig creation logic.
 func runKubeConfigFile(kubeConfigFileName string) func(workflow.RunData) error {
 	return func(c workflow.RunData) error {
-		data, ok := c.(kubeConfigData)
+		data, ok := c.(InitData)
 		if !ok {
 			return errors.New("kubeconfig phase invoked with an invalid data struct")
 		}

cmd/kubeadm/app/cmd/phases/init/kubelet.go

@@ -19,7 +19,6 @@ package phases
 import (
 	"github.com/pkg/errors"
 	"k8s.io/klog"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	kubeletphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/kubelet"
@@ -33,15 +32,6 @@ var (
 		`)
 )
 
-// kubeletStartData defines the behavior that a runtime data struct passed to the kubelet start phase
-// should have. Please note that we are using an interface in order to make this phase reusable in different workflows
-// (and thus with different runtime data struct, all of them requested to be compliant to this interface)
-type kubeletStartData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	DryRun() bool
-	KubeletDir() string
-}
-
 // NewKubeletStartPhase creates a kubeadm workflow phase that start kubelet on a node.
 func NewKubeletStartPhase() workflow.Phase {
 	return workflow.Phase{
@@ -60,7 +50,7 @@ func NewKubeletStartPhase() workflow.Phase {
 
 // runKubeletStart executes kubelet start logic.
 func runKubeletStart(c workflow.RunData) error {
-	data, ok := c.(kubeletStartData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("kubelet-start phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/init/markcontrolplane.go

@@ -18,8 +18,6 @@ package phases
 
 import (
 	"github.com/pkg/errors"
-	clientset "k8s.io/client-go/kubernetes"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	markcontrolplanephase "k8s.io/kubernetes/cmd/kubeadm/app/phases/markcontrolplane"
@@ -36,12 +34,6 @@ var (
 		`)
 )
 
-type markControlPlaneData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	Client() (clientset.Interface, error)
-	DryRun() bool
-}
-
 // NewMarkControlPlanePhase creates a kubeadm workflow phase that implements mark-controlplane checks.
 func NewMarkControlPlanePhase() workflow.Phase {
 	return workflow.Phase{
@@ -58,7 +50,7 @@ func NewMarkControlPlanePhase() workflow.Phase {
 
 // runMarkControlPlane executes mark-control-plane checks logic.
 func runMarkControlPlane(c workflow.RunData) error {
-	data, ok := c.(markControlPlaneData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("mark-control-plane phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/init/preflight.go

@@ -20,8 +20,6 @@ import (
 	"fmt"
 
 	"github.com/pkg/errors"
-	"k8s.io/apimachinery/pkg/util/sets"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	"k8s.io/kubernetes/cmd/kubeadm/app/preflight"
@@ -36,15 +34,6 @@ var (
 		`)
 )
 
-// preflightData defines the behavior that a runtime data struct passed to the Preflight phase
-// should have. Please note that we are using an interface in order to make this phase reusable in different workflows
-// (and thus with different runtime data struct, all of them requested to be compliant to this interface)
-type preflightData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	DryRun() bool
-	IgnorePreflightErrors() sets.String
-}
-
 // NewPreflightPhase creates a kubeadm workflow phase that implements preflight checks for a new control-plane node.
 func NewPreflightPhase() workflow.Phase {
 	return workflow.Phase{
@@ -62,7 +51,7 @@ func NewPreflightPhase() workflow.Phase {
 
 // runPreflight executes preflight checks logic.
 func runPreflight(c workflow.RunData) error {
-	data, ok := c.(preflightData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("preflight phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/init/uploadcerts.go

@@ -21,9 +21,7 @@ import (
 
 	"github.com/pkg/errors"
 
-	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/klog"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -31,14 +29,6 @@ import (
 	"k8s.io/kubernetes/cmd/kubeadm/app/phases/uploadcerts"
 )
 
-type uploadCertsData interface {
-	Client() (clientset.Interface, error)
-	UploadCerts() bool
-	Cfg() *kubeadmapi.InitConfiguration
-	CertificateKey() string
-	SetCertificateKey(key string)
-}
-
 // NewUploadCertsPhase returns the uploadCerts phase
 func NewUploadCertsPhase() workflow.Phase {
 	return workflow.Phase{
@@ -54,7 +44,7 @@ func NewUploadCertsPhase() workflow.Phase {
 }
 
 func runUploadCerts(c workflow.RunData) error {
-	data, ok := c.(uploadCertsData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("upload-certs phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/init/uploadconfig.go

@@ -58,11 +58,6 @@ var (
 		`)
 )
 
-type uploadConfigData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	Client() (clientset.Interface, error)
-}
-
 // NewUploadConfigPhase returns the phase to uploadConfig
 func NewUploadConfigPhase() workflow.Phase {
 	return workflow.Phase{
@@ -138,7 +133,7 @@ func runUploadKubeletConfig(c workflow.RunData) error {
 }
 
 func getUploadConfigData(c workflow.RunData) (*kubeadmapi.InitConfiguration, clientset.Interface, error) {
-	data, ok := c.(uploadConfigData)
+	data, ok := c.(InitData)
 	if !ok {
 		return nil, nil, errors.New("upload-config phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/init/waitcontrolplane.go

@@ -27,7 +27,6 @@ import (
 	"github.com/pkg/errors"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/klog"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/util/apiclient"
@@ -56,14 +55,6 @@ var (
 	`)))
 )
 
-type waitControlPlaneData interface {
-	Cfg() *kubeadmapi.InitConfiguration
-	ManifestDir() string
-	DryRun() bool
-	Client() (clientset.Interface, error)
-	OutputWriter() io.Writer
-}
-
 // NewWaitControlPlanePhase is a hidden phase that runs after the control-plane and etcd phases
 func NewWaitControlPlanePhase() workflow.Phase {
 	phase := workflow.Phase{
@@ -75,7 +66,7 @@ func NewWaitControlPlanePhase() workflow.Phase {
 }
 
 func runWaitControlPlanePhase(c workflow.RunData) error {
-	data, ok := c.(waitControlPlaneData)
+	data, ok := c.(InitData)
 	if !ok {
 		return errors.New("wait-control-plane phase invoked with an invalid data struct")
 	}
@@ -113,7 +104,7 @@ func runWaitControlPlanePhase(c workflow.RunData) error {
 }
 
 // printFilesIfDryRunning prints the Static Pod manifests to stdout and informs about the temporary directory to go and lookup
-func printFilesIfDryRunning(data waitControlPlaneData) error {
+func printFilesIfDryRunning(data InitData) error {
 	if !data.DryRun() {
 		return nil
 	}

cmd/kubeadm/app/cmd/phases/join/BUILD

@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "go_default_library",
@@ -6,6 +6,7 @@ go_library(
         "checketcd.go",
         "controlplanejoin.go",
         "controlplaneprepare.go",
+        "data.go",
         "kubelet.go",
         "preflight.go",
     ],
@@ -54,3 +55,15 @@ filegroup(
     tags = ["automanaged"],
     visibility = ["//visibility:public"],
 )
+
+go_test(
+    name = "go_default_test",
+    srcs = ["data_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
+        "//staging/src/k8s.io/client-go/tools/clientcmd/api:go_default_library",
+    ],
+)

cmd/kubeadm/app/cmd/phases/join/checketcd.go

@@ -20,19 +20,11 @@ import (
 	"fmt"
 
 	"github.com/pkg/errors"
-	clientset "k8s.io/client-go/kubernetes"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	etcdphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/etcd"
 )
 
-type checkEtcdData interface {
-	Cfg() *kubeadmapi.JoinConfiguration
-	ClientSetFromFile(string) (*clientset.Clientset, error)
-	InitCfg() (*kubeadmapi.InitConfiguration, error)
-}
-
 // NewCheckEtcdPhase is a hidden phase that runs after the control-plane-prepare and
 // before the bootstrap-kubelet phase that ensures etcd is healthy
 func NewCheckEtcdPhase() workflow.Phase {
@@ -44,7 +36,7 @@ func NewCheckEtcdPhase() workflow.Phase {
 }
 
 func runCheckEtcdPhase(c workflow.RunData) error {
-	data, ok := c.(checkEtcdData)
+	data, ok := c.(JoinData)
 	if !ok {
 		return errors.New("check-etcd phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/join/controlplanejoin.go

@@ -20,8 +20,6 @@ import (
 	"fmt"
 
 	"github.com/pkg/errors"
-	clientset "k8s.io/client-go/kubernetes"
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -39,13 +37,6 @@ var (
 		`)
 )
 
-type controlPlaneJoinData interface {
-	Cfg() *kubeadmapi.JoinConfiguration
-	ClientSetFromFile(string) (*clientset.Clientset, error)
-	InitCfg() (*kubeadmapi.InitConfiguration, error)
-	KubeConfigPath() string
-}
-
 func getControlPlaneJoinPhaseFlags() []string {
 	return []string{
 		options.APIServerAdvertiseAddress,
@@ -109,7 +100,7 @@ func newMarkControlPlaneSubphase() workflow.Phase {
 }
 
 func runEtcdPhase(c workflow.RunData) error {
-	data, ok := c.(controlPlaneJoinData)
+	data, ok := c.(JoinData)
 	if !ok {
 		return errors.New("control-plane-join phase invoked with an invalid data struct")
 	}
@@ -151,7 +142,7 @@ func runEtcdPhase(c workflow.RunData) error {
 }
 
 func runUploadConfigPhase(c workflow.RunData) error {
-	data, ok := c.(controlPlaneJoinData)
+	data, ok := c.(JoinData)
 	if !ok {
 		return errors.New("control-plane-join phase invoked with an invalid data struct")
 	}
@@ -179,7 +170,7 @@ func runUploadConfigPhase(c workflow.RunData) error {
 }
 
 func runMarkControlPlanePhase(c workflow.RunData) error {
-	data, ok := c.(controlPlaneJoinData)
+	data, ok := c.(JoinData)
 	if !ok {
 		return errors.New("control-plane-join phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/join/controlplaneprepare.go

@@ -21,7 +21,6 @@ import (
 
 	"github.com/pkg/errors"
 
-	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/phases/workflow"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -31,11 +30,6 @@ import (
 	kubeconfigphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/kubeconfig"
 )
 
-type controlPlanePrepareData interface {
-	Cfg() *kubeadmapi.JoinConfiguration
-	InitCfg() (*kubeadmapi.InitConfiguration, error)
-}
-
 // NewControlPlanePreparePhase creates a kubeadm workflow phase that implements the preparation of the node to serve a control plane
 func NewControlPlanePreparePhase() workflow.Phase {
 	return workflow.Phase{
@@ -97,7 +91,7 @@ func newControlPlanePrepareManifestsSubphases() workflow.Phase {
 }
 
 func runControlPlanePrepareManifestsSubphase(c workflow.RunData) error {
-	data, ok := c.(controlPlanePrepareData)
+	data, ok := c.(JoinData)
 	if !ok {
 		return errors.New("control-plane-prepare phase invoked with an invalid data struct")
 	}
@@ -117,7 +111,7 @@ func runControlPlanePrepareManifestsSubphase(c workflow.RunData) error {
 }
 
 func runControlPlanePrepareCertsPhaseLocal(c workflow.RunData) error {
-	data, ok := c.(controlPlanePrepareData)
+	data, ok := c.(JoinData)
 	if !ok {
 		return errors.New("control-plane-prepare phase invoked with an invalid data struct")
 	}
@@ -137,7 +131,7 @@ func runControlPlanePrepareCertsPhaseLocal(c workflow.RunData) error {
 }
 
 func runControlPlanePrepareKubeconfigPhaseLocal(c workflow.RunData) error {
-	data, ok := c.(controlPlanePrepareData)
+	data, ok := c.(JoinData)
 	if !ok {
 		return errors.New("control-plane-prepare phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/join/data.go

@@ -0,0 +1,38 @@
+/*
+Copyright 2019 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 phases
+
+import (
+	"io"
+
+	"k8s.io/apimachinery/pkg/util/sets"
+	clientset "k8s.io/client-go/kubernetes"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+)
+
+// JoinData is the interface to use for join phases.
+// The "joinData" type from "cmd/join.go" must satisfy this interface.
+type JoinData interface {
+	Cfg() *kubeadmapi.JoinConfiguration
+	KubeConfigPath() string
+	TLSBootstrapCfg() (*clientcmdapi.Config, error)
+	InitCfg() (*kubeadmapi.InitConfiguration, error)
+	ClientSetFromFile(path string) (*clientset.Clientset, error)
+	IgnorePreflightErrors() sets.String
+	OutputWriter() io.Writer
+}

cmd/kubeadm/app/cmd/phases/join/data_test.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2019 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 phases
+
+import (
+	"io"
+
+	"k8s.io/apimachinery/pkg/util/sets"
+	clientset "k8s.io/client-go/kubernetes"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+)
+
+// a package local type for testing purposes.
+type testJoinData struct{}
+
+// testJoinData must satisfy JoinData.
+var _ JoinData = &testJoinData{}
+
+func (j *testJoinData) Cfg() *kubeadmapi.JoinConfiguration                          { return nil }
+func (j *testJoinData) KubeConfigPath() string                                      { return "" }
+func (j *testJoinData) TLSBootstrapCfg() (*clientcmdapi.Config, error)              { return nil, nil }
+func (j *testJoinData) InitCfg() (*kubeadmapi.InitConfiguration, error)             { return nil, nil }
+func (j *testJoinData) ClientSetFromFile(path string) (*clientset.Clientset, error) { return nil, nil }
+func (j *testJoinData) IgnorePreflightErrors() sets.String                          { return nil }
+func (j *testJoinData) OutputWriter() io.Writer                                     { return nil }

cmd/kubeadm/app/cmd/phases/join/kubelet.go

@@ -23,7 +23,6 @@ import (
 	"github.com/lithammer/dedent"
 	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/util/wait"
-	clientset "k8s.io/client-go/kubernetes"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 	certutil "k8s.io/client-go/util/cert"
 	"k8s.io/klog"
@@ -54,13 +53,6 @@ var (
 		`)
 )
 
-type kubeletStartData interface {
-	Cfg() *kubeadmapi.JoinConfiguration
-	ClientSetFromFile(path string) (*clientset.Clientset, error)
-	InitCfg() (*kubeadmapi.InitConfiguration, error)
-	TLSBootstrapCfg() (*clientcmdapi.Config, error)
-}
-
 // NewKubeletStartPhase creates a kubeadm workflow phase that start kubelet on a node.
 func NewKubeletStartPhase() workflow.Phase {
 	return workflow.Phase{
@@ -81,8 +73,8 @@ func NewKubeletStartPhase() workflow.Phase {
 	}
 }
 
-func getKubeletStartJoinData(c workflow.RunData) (kubeletStartData, *kubeadmapi.JoinConfiguration, *kubeadmapi.InitConfiguration, *clientcmdapi.Config, error) {
-	data, ok := c.(kubeletStartData)
+func getKubeletStartJoinData(c workflow.RunData) (JoinData, *kubeadmapi.JoinConfiguration, *kubeadmapi.InitConfiguration, *clientcmdapi.Config, error) {
+	data, ok := c.(JoinData)
 	if !ok {
 		return nil, nil, nil, nil, errors.New("kubelet-start phase invoked with an invalid data struct")
 	}

cmd/kubeadm/app/cmd/phases/join/preflight.go

@@ -23,7 +23,6 @@ import (
 
 	"github.com/lithammer/dedent"
 	"github.com/pkg/errors"
-	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/klog"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
@@ -52,12 +51,6 @@ var (
 		`)))
 )
 
-type preflightData interface {
-	Cfg() *kubeadmapi.JoinConfiguration
-	InitCfg() (*kubeadmapi.InitConfiguration, error)
-	IgnorePreflightErrors() sets.String
-}
-
 // NewPreflightPhase creates a kubeadm workflow phase that implements preflight checks for a new node join
 func NewPreflightPhase() workflow.Phase {
 	return workflow.Phase{
@@ -86,7 +79,7 @@ func NewPreflightPhase() workflow.Phase {
 
 // runPreflight executes preflight checks logic.
 func runPreflight(c workflow.RunData) error {
-	j, ok := c.(preflightData)
+	j, ok := c.(JoinData)
 	if !ok {
 		return errors.New("preflight phase invoked with an invalid data struct")
 	}