Prepulls images by default

kubeadm now pulls container images before the init step if it cannot find them on the system

* This commit also cleans up a dependency cycle

Closes #825

cmd/kubeadm/app/cmd/config.go

@@ -301,7 +301,7 @@ func NewCmdConfigImagesPull() *cobra.Command {
 			kubeadmutil.CheckErr(err)
 			internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(cfgPath, cfg)
 			kubeadmutil.CheckErr(err)
-			puller, err := images.NewImagePuller(utilsexec.New(), internalcfg.GetCRISocket())
+			puller, err := images.NewCRInterfacer(utilsexec.New(), internalcfg.GetCRISocket())
 			kubeadmutil.CheckErr(err)
 			imagesPull := NewImagesPull(puller, images.GetAllImages(internalcfg))
 			kubeadmutil.CheckErr(imagesPull.PullAll())

cmd/kubeadm/app/cmd/init.go

@@ -258,6 +258,9 @@ func NewInit(cfgPath string, externalcfg *kubeadmapiv1alpha2.MasterConfiguration
 	if err := preflight.RunInitMasterChecks(utilsexec.New(), cfg, ignorePreflightErrors); err != nil {
 		return nil, err
 	}
+	if err := preflight.RunPullImagesCheck(utilsexec.New(), cfg, ignorePreflightErrors); err != nil {
+		return nil, err
+	}
 
 	return &Init{cfg: cfg, skipTokenPrint: skipTokenPrint, dryRun: dryRun, ignorePreflightErrors: ignorePreflightErrors}, nil
 }

cmd/kubeadm/app/images/BUILD

@@ -10,12 +10,12 @@ go_library(
     name = "go_default_library",
     srcs = [
         "images.go",
-        "puller.go",
+        "interface.go",
     ],
     importpath = "k8s.io/kubernetes/cmd/kubeadm/app/images",
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
-        "//cmd/kubeadm/app/apis/kubeadm/v1alpha1:go_default_library",
+        "//cmd/kubeadm/app/apis/kubeadm/v1alpha2:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
         "//cmd/kubeadm/app/features:go_default_library",
         "//cmd/kubeadm/app/phases/addons/dns:go_default_library",
@@ -46,10 +46,10 @@ filegroup(
 
 go_test(
     name = "go_default_xtest",
-    srcs = ["puller_test.go"],
+    srcs = ["interface_test.go"],
     deps = [
         ":go_default_library",
-        "//cmd/kubeadm/app/apis/kubeadm/v1alpha1:go_default_library",
+        "//cmd/kubeadm/app/apis/kubeadm/v1alpha2:go_default_library",
         "//vendor/k8s.io/utils/exec:go_default_library",
     ],
 )

cmd/kubeadm/app/images/interface.go

@@ -0,0 +1,89 @@
+/*
+Copyright 2018 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 images
+
+import (
+	"fmt"
+
+	kubeadmapiv1alpha2 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha2"
+	utilsexec "k8s.io/utils/exec"
+)
+
+// Puller is an interface for pulling images
+type Puller interface {
+	Pull(string) error
+}
+
+// Existence is an interface to determine if an image exists on the system
+// A nil error means the image was found
+type Existence interface {
+	Exists(string) error
+}
+
+// Images defines the set of behaviors needed for images relating to the CRI
+type Images interface {
+	Puller
+	Existence
+}
+
+// CRInterfacer is a struct that interfaces with the container runtime
+type CRInterfacer struct {
+	criSocket  string
+	exec       utilsexec.Interface
+	crictlPath string
+	dockerPath string
+}
+
+// NewCRInterfacer sets up and returns a CRInterfacer
+func NewCRInterfacer(execer utilsexec.Interface, criSocket string) (*CRInterfacer, error) {
+	var crictlPath, dockerPath string
+	var err error
+	if criSocket != kubeadmapiv1alpha2.DefaultCRISocket {
+		if crictlPath, err = execer.LookPath("crictl"); err != nil {
+			return nil, fmt.Errorf("crictl is required for non docker container runtimes: %v", err)
+		}
+	} else {
+		// use the dockershim
+		if dockerPath, err = execer.LookPath("docker"); err != nil {
+			return nil, fmt.Errorf("`docker` is required when docker is the container runtime and the kubelet is not running: %v", err)
+		}
+	}
+
+	return &CRInterfacer{
+		exec:       execer,
+		criSocket:  criSocket,
+		crictlPath: crictlPath,
+		dockerPath: dockerPath,
+	}, nil
+}
+
+// Pull pulls the actual image using either crictl or docker
+func (cri *CRInterfacer) Pull(image string) error {
+	if cri.criSocket != kubeadmapiv1alpha2.DefaultCRISocket {
+		return cri.exec.Command(cri.crictlPath, "-r", cri.criSocket, "pull", image).Run()
+	}
+	return cri.exec.Command(cri.dockerPath, "pull", image).Run()
+}
+
+// Exists checks to see if the image exists on the system already
+// Returns an error if the image is not found.
+func (cri *CRInterfacer) Exists(image string) error {
+	if cri.criSocket != kubeadmapiv1alpha2.DefaultCRISocket {
+		return cri.exec.Command(cri.crictlPath, "-r", cri.criSocket, "inspecti", image).Run()
+	}
+	return cri.exec.Command(cri.dockerPath, "inspect", image).Run()
+}

cmd/kubeadm/app/images/interface_test.go

@@ -0,0 +1,266 @@
+/*
+Copyright 2018 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 images_test
+
+import (
+	"context"
+	"errors"
+	"io"
+	"testing"
+
+	kubeadmapiv1alpha2 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha2"
+	"k8s.io/kubernetes/cmd/kubeadm/app/images"
+	"k8s.io/utils/exec"
+)
+
+type fakeCmd struct {
+	err error
+}
+
+func (f *fakeCmd) Run() error {
+	return f.err
+}
+func (f *fakeCmd) CombinedOutput() ([]byte, error) { return nil, nil }
+func (f *fakeCmd) Output() ([]byte, error)         { return nil, nil }
+func (f *fakeCmd) SetDir(dir string)               {}
+func (f *fakeCmd) SetStdin(in io.Reader)           {}
+func (f *fakeCmd) SetStdout(out io.Writer)         {}
+func (f *fakeCmd) SetStderr(out io.Writer)         {}
+func (f *fakeCmd) Stop()                           {}
+
+type fakeExecer struct {
+	cmd        exec.Cmd
+	findCrictl bool
+	findDocker bool
+}
+
+func (f *fakeExecer) Command(cmd string, args ...string) exec.Cmd { return f.cmd }
+func (f *fakeExecer) CommandContext(ctx context.Context, cmd string, args ...string) exec.Cmd {
+	return f.cmd
+}
+func (f *fakeExecer) LookPath(file string) (string, error) {
+	if file == "crictl" {
+		if f.findCrictl {
+			return "/path", nil
+		}
+		return "", errors.New("no crictl for you")
+	}
+	if file == "docker" {
+		if f.findDocker {
+			return "/path", nil
+		}
+		return "", errors.New("no docker for you")
+	}
+	return "", errors.New("unknown binary")
+}
+
+func TestNewCRInterfacer(t *testing.T) {
+	testcases := []struct {
+		name        string
+		criSocket   string
+		findCrictl  bool
+		findDocker  bool
+		expectError bool
+	}{
+		{
+			name:        "need crictl but can only find docker should return an error",
+			criSocket:   "/not/docker",
+			findCrictl:  false,
+			findDocker:  true,
+			expectError: true,
+		},
+		{
+			name:        "need crictl and cannot find either should return an error",
+			criSocket:   "/not/docker",
+			findCrictl:  false,
+			findDocker:  false,
+			expectError: true,
+		},
+		{
+			name:        "need crictl and cannot find docker should return no error",
+			criSocket:   "/not/docker",
+			findCrictl:  true,
+			findDocker:  false,
+			expectError: false,
+		},
+		{
+			name:        "need crictl and can find both should return no error",
+			criSocket:   "/not/docker",
+			findCrictl:  true,
+			findDocker:  true,
+			expectError: false,
+		},
+		{
+			name:        "need docker and cannot find crictl should return no error",
+			criSocket:   kubeadmapiv1alpha2.DefaultCRISocket,
+			findCrictl:  false,
+			findDocker:  true,
+			expectError: false,
+		},
+		{
+			name:        "need docker and cannot find docker should return an error",
+			criSocket:   kubeadmapiv1alpha2.DefaultCRISocket,
+			findCrictl:  false,
+			findDocker:  false,
+			expectError: true,
+		},
+		{
+			name:        "need docker and can find both should return no error",
+			criSocket:   kubeadmapiv1alpha2.DefaultCRISocket,
+			findCrictl:  true,
+			findDocker:  true,
+			expectError: false,
+		},
+		{
+			name:        "need docker and can only find crictl should return an error",
+			criSocket:   kubeadmapiv1alpha2.DefaultCRISocket,
+			findCrictl:  true,
+			findDocker:  false,
+			expectError: true,
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			fe := &fakeExecer{
+				findCrictl: tc.findCrictl,
+				findDocker: tc.findDocker,
+			}
+			_, err := images.NewCRInterfacer(fe, tc.criSocket)
+			if tc.expectError && err == nil {
+				t.Fatal("expected an error but did not get one")
+			}
+			if !tc.expectError && err != nil {
+				t.Fatalf("did not expedt an error but got an error: %v", err)
+			}
+		})
+	}
+}
+
+func TestImagePuller(t *testing.T) {
+	testcases := []struct {
+		name          string
+		criSocket     string
+		pullFails     bool
+		errorExpected bool
+	}{
+		{
+			name:          "using docker and pull fails",
+			criSocket:     kubeadmapiv1alpha2.DefaultCRISocket,
+			pullFails:     true,
+			errorExpected: true,
+		},
+		{
+			name:          "using docker and pull succeeds",
+			criSocket:     kubeadmapiv1alpha2.DefaultCRISocket,
+			pullFails:     false,
+			errorExpected: false,
+		},
+		{
+			name:          "using crictl pull fails",
+			criSocket:     "/not/default",
+			pullFails:     true,
+			errorExpected: true,
+		},
+		{
+			name:          "using crictl and pull succeeds",
+			criSocket:     "/not/default",
+			pullFails:     false,
+			errorExpected: false,
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			var err error
+			if tc.pullFails {
+				err = errors.New("error")
+			}
+
+			fe := &fakeExecer{
+				cmd:        &fakeCmd{err},
+				findCrictl: true,
+				findDocker: true,
+			}
+			ip, _ := images.NewCRInterfacer(fe, tc.criSocket)
+
+			err = ip.Pull("imageName")
+			if tc.errorExpected && err == nil {
+				t.Fatal("expected an error and did not get one")
+			}
+			if !tc.errorExpected && err != nil {
+				t.Fatalf("expected no error but got one: %v", err)
+			}
+		})
+	}
+}
+
+func TestImageExists(t *testing.T) {
+	testcases := []struct {
+		name          string
+		criSocket     string
+		existFails    bool
+		errorExpected bool
+	}{
+		{
+			name:          "using docker and exist fails",
+			criSocket:     kubeadmapiv1alpha2.DefaultCRISocket,
+			existFails:    true,
+			errorExpected: true,
+		},
+		{
+			name:          "using docker and exist succeeds",
+			criSocket:     kubeadmapiv1alpha2.DefaultCRISocket,
+			existFails:    false,
+			errorExpected: false,
+		},
+		{
+			name:          "using crictl exist fails",
+			criSocket:     "/not/default",
+			existFails:    true,
+			errorExpected: true,
+		},
+		{
+			name:          "using crictl and exist succeeds",
+			criSocket:     "/not/default",
+			existFails:    false,
+			errorExpected: false,
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			var err error
+			if tc.existFails {
+				err = errors.New("error")
+			}
+
+			fe := &fakeExecer{
+				cmd:        &fakeCmd{err},
+				findCrictl: true,
+				findDocker: true,
+			}
+			ip, _ := images.NewCRInterfacer(fe, tc.criSocket)
+
+			err = ip.Exists("imageName")
+			if tc.errorExpected && err == nil {
+				t.Fatal("expected an error and did not get one")
+			}
+			if !tc.errorExpected && err != nil {
+				t.Fatalf("expected no error but got one: %v", err)
+			}
+		})
+	}
+}

cmd/kubeadm/app/images/puller.go

@@ -1,57 +0,0 @@
-/*
-Copyright 2018 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 images
-
-import (
-	"fmt"
-
-	kubeadmapiv1alpha1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
-	utilsexec "k8s.io/utils/exec"
-)
-
-// Puller is an interface for pulling images
-type Puller interface {
-	Pull(string) error
-}
-
-// ImagePuller is a struct that can pull images and hides the implementation (crictl vs docker)
-type ImagePuller struct {
-	criSocket  string
-	exec       utilsexec.Interface
-	crictlPath string
-}
-
-// NewImagePuller returns a ready to go ImagePuller
-func NewImagePuller(execer utilsexec.Interface, criSocket string) (*ImagePuller, error) {
-	crictlPath, err := execer.LookPath("crictl")
-	if err != nil && criSocket != kubeadmapiv1alpha1.DefaultCRISocket {
-		return nil, fmt.Errorf("crictl is required for non docker container runtimes: %v", err)
-	}
-	return &ImagePuller{
-		exec:       execer,
-		criSocket:  criSocket,
-		crictlPath: crictlPath,
-	}, nil
-}
-
-// Pull pulls the actual image using either crictl or docker
-func (ip *ImagePuller) Pull(image string) error {
-	if ip.criSocket != kubeadmapiv1alpha1.DefaultCRISocket {
-		return ip.exec.Command(ip.crictlPath, "-r", ip.criSocket, "pull", image).Run()
-	}
-	return ip.exec.Command("sh", "-c", fmt.Sprintf("docker pull %v", image)).Run()
-}

cmd/kubeadm/app/images/puller_test.go

@@ -1,138 +0,0 @@
-/*
-Copyright 2018 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 images_test
-
-import (
-	"bytes"
-	"context"
-	"errors"
-	"fmt"
-	"io"
-	"os"
-	"strings"
-	"testing"
-
-	kubeadmdefaults "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
-	"k8s.io/kubernetes/cmd/kubeadm/app/images"
-	"k8s.io/utils/exec"
-)
-
-type fakeCmd struct {
-	cmd  string
-	args []string
-	out  io.Writer
-}
-
-func (f *fakeCmd) Run() error {
-	fmt.Fprintf(f.out, "%v %v", f.cmd, strings.Join(f.args, " "))
-	return nil
-}
-func (f *fakeCmd) CombinedOutput() ([]byte, error) { return nil, nil }
-func (f *fakeCmd) Output() ([]byte, error)         { return nil, nil }
-func (f *fakeCmd) SetDir(dir string)               {}
-func (f *fakeCmd) SetStdin(in io.Reader)           {}
-func (f *fakeCmd) SetStdout(out io.Writer) {
-	f.out = out
-}
-func (f *fakeCmd) SetStderr(out io.Writer) {}
-func (f *fakeCmd) Stop()                   {}
-
-type fakeExecer struct {
-	cmd              exec.Cmd
-	lookPathSucceeds bool
-}
-
-func (f *fakeExecer) Command(cmd string, args ...string) exec.Cmd { return f.cmd }
-func (f *fakeExecer) CommandContext(ctx context.Context, cmd string, args ...string) exec.Cmd {
-	return f.cmd
-}
-func (f *fakeExecer) LookPath(file string) (string, error) {
-	if f.lookPathSucceeds {
-		return file, nil
-	}
-	return "", &os.PathError{Err: errors.New("does not exist")}
-}
-
-func TestImagePuller(t *testing.T) {
-	testcases := []struct {
-		name          string
-		criSocket     string
-		cmd           exec.Cmd
-		findCrictl    bool
-		expected      string
-		errorExpected bool
-	}{
-		{
-			name:      "New succeeds even if crictl is not in path",
-			criSocket: kubeadmdefaults.DefaultCRISocket,
-			cmd: &fakeCmd{
-				cmd:  "hello",
-				args: []string{"world", "and", "friends"},
-			},
-			findCrictl: false,
-			expected:   "hello world and friends",
-		},
-		{
-			name:      "New succeeds with crictl in path",
-			criSocket: "/not/default",
-			cmd: &fakeCmd{
-				cmd:  "crictl",
-				args: []string{"-r", "/some/socket", "imagename"},
-			},
-			findCrictl: true,
-			expected:   "crictl -r /some/socket imagename",
-		},
-		{
-			name:      "New fails with crictl not in path but is required",
-			criSocket: "/not/docker",
-			cmd: &fakeCmd{
-				cmd:  "crictl",
-				args: []string{"-r", "/not/docker", "an image"},
-			},
-			findCrictl:    false,
-			errorExpected: true,
-		},
-	}
-	for _, tc := range testcases {
-		t.Run(tc.name, func(t *testing.T) {
-			var b bytes.Buffer
-			tc.cmd.SetStdout(&b)
-			fe := &fakeExecer{
-				cmd:              tc.cmd,
-				lookPathSucceeds: tc.findCrictl,
-			}
-			ip, err := images.NewImagePuller(fe, tc.criSocket)
-
-			if tc.errorExpected {
-				if err == nil {
-					t.Fatalf("expected an error but found nil: %v", fe)
-				}
-				return
-			}
-
-			if err != nil {
-				t.Fatalf("expected nil but found an error: %v", err)
-			}
-			if err = ip.Pull("imageName"); err != nil {
-				t.Fatalf("expected nil pulling an image but found: %v", err)
-			}
-			if b.String() != tc.expected {
-				t.Fatalf("expected %v but got: %v", tc.expected, b.String())
-			}
-		})
-	}
-}

cmd/kubeadm/app/preflight/BUILD

@@ -52,6 +52,7 @@ go_library(
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/apis/kubeadm/v1alpha1:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
+        "//cmd/kubeadm/app/images:go_default_library",
         "//pkg/apis/core/validation:go_default_library",
         "//pkg/registry/core/service/ipallocator:go_default_library",
         "//pkg/util/initsystem:go_default_library",

cmd/kubeadm/app/preflight/checks.go

@@ -46,6 +46,7 @@ import (
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmdefaults "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	"k8s.io/kubernetes/cmd/kubeadm/app/images"
 	"k8s.io/kubernetes/pkg/apis/core/validation"
 	"k8s.io/kubernetes/pkg/registry/core/service/ipallocator"
 	"k8s.io/kubernetes/pkg/util/initsystem"
@@ -76,10 +77,16 @@ type Error struct {
 	Msg string
 }
 
+// Error implements the standard error interface
 func (e *Error) Error() string {
 	return fmt.Sprintf("[preflight] Some fatal errors occurred:\n%s%s", e.Msg, "[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`")
 }
 
+// Preflight identifies this error as a preflight error
+func (e *Error) Preflight() bool {
+	return true
+}
+
 // Checker validates the state of the system to ensure kubeadm will be
 // successful as often as possible.
 type Checker interface {
@@ -850,6 +857,30 @@ func (ResolveCheck) Check() (warnings, errors []error) {
 	return warnings, errors
 }
 
+// ImagePullCheck will pull container images used by kubeadm
+type ImagePullCheck struct {
+	Images    images.Images
+	ImageList []string
+}
+
+// Name returns the label for ImagePullCheck
+func (ImagePullCheck) Name() string {
+	return "ImagePull"
+}
+
+// Check pulls images required by kubeadm. This is a mutating check
+func (i ImagePullCheck) Check() (warnings, errors []error) {
+	for _, image := range i.ImageList {
+		if err := i.Images.Exists(image); err == nil {
+			continue
+		}
+		if err := i.Images.Pull(image); err != nil {
+			errors = append(errors, fmt.Errorf("failed to pull image [%s]: %v", image, err))
+		}
+	}
+	return warnings, errors
+}
+
 // RunInitMasterChecks executes all individual, applicable to Master node checks.
 func RunInitMasterChecks(execer utilsexec.Interface, cfg *kubeadmapi.MasterConfiguration, ignorePreflightErrors sets.String) error {
 	// First, check if we're root separately from the other preflight checks and fail fast
@@ -1012,6 +1043,19 @@ func RunRootCheckOnly(ignorePreflightErrors sets.String) error {
 	return RunChecks(checks, os.Stderr, ignorePreflightErrors)
 }
 
+// RunPullImagesCheck will pull images kubeadm needs if the are not found on the system
+func RunPullImagesCheck(execer utilsexec.Interface, cfg *kubeadmapi.MasterConfiguration, ignorePreflightErrors sets.String) error {
+	criInterfacer, err := images.NewCRInterfacer(execer, cfg.GetCRISocket())
+	if err != nil {
+		return err
+	}
+
+	checks := []Checker{
+		ImagePullCheck{Images: criInterfacer, ImageList: images.GetAllImages(cfg)},
+	}
+	return RunChecks(checks, os.Stderr, ignorePreflightErrors)
+}
+
 // RunChecks runs each check, displays it's warnings/errors, and once all
 // are processed will exit if any errors occurred.
 func RunChecks(checks []Checker, ww io.Writer, ignorePreflightErrors sets.String) error {

cmd/kubeadm/app/preflight/checks_test.go

@@ -18,6 +18,7 @@ package preflight
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"strings"
@@ -696,3 +697,32 @@ func TestSetHasItemOrAll(t *testing.T) {
 		}
 	}
 }
+
+type imgs struct{}
+
+func (i *imgs) Pull(image string) error {
+	if image == "bad pull" {
+		return errors.New("pull error")
+	}
+	return nil
+}
+func (i *imgs) Exists(image string) error {
+	if image == "found" {
+		return nil
+	}
+	return errors.New("error")
+}
+
+func TestImagePullCheck(t *testing.T) {
+	i := ImagePullCheck{
+		Images:    &imgs{},
+		ImageList: []string{"found", "not found", "bad pull"},
+	}
+	warnings, errors := i.Check()
+	if len(warnings) != 0 {
+		t.Fatalf("did not expect any warnings but got %q", warnings)
+	}
+	if len(errors) != 1 {
+		t.Fatalf("expected 1 errors but got %d: %q", len(errors), errors)
+	}
+}

cmd/kubeadm/app/util/BUILD

@@ -20,7 +20,6 @@ go_library(
     importpath = "k8s.io/kubernetes/cmd/kubeadm/app/util",
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
-        "//cmd/kubeadm/app/preflight:go_default_library",
         "//vendor/gopkg.in/yaml.v2:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
@@ -47,7 +46,6 @@ go_test(
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/apis/kubeadm/scheme:go_default_library",
         "//cmd/kubeadm/app/apis/kubeadm/v1alpha1:go_default_library",
-        "//cmd/kubeadm/app/preflight:go_default_library",
         "//vendor/k8s.io/api/core/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
     ],

cmd/kubeadm/app/util/error.go

@@ -22,7 +22,6 @@ import (
 	"strings"
 
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
-	"k8s.io/kubernetes/cmd/kubeadm/app/preflight"
 )
 
 const (
@@ -60,13 +59,19 @@ func CheckErr(err error) {
 	checkErr("", err, fatal)
 }
 
+// preflightError allows us to know if the error is a preflight error or not
+// defining the interface here avoids an import cycle of pulling in preflight into the util package
+type preflightError interface {
+	Preflight() bool
+}
+
 // checkErr formats a given error as a string and calls the passed handleErr
 // func with that string and an kubectl exit code.
 func checkErr(prefix string, err error, handleErr func(string, int)) {
 	switch err.(type) {
 	case nil:
 		return
-	case *preflight.Error:
+	case preflightError:
 		handleErr(err.Error(), PreFlightExitCode)
 	case utilerrors.Aggregate:
 		handleErr(err.Error(), ValidationExitCode)

cmd/kubeadm/app/util/error_test.go

@@ -19,10 +19,12 @@ package util
 import (
 	"fmt"
 	"testing"
-
-	"k8s.io/kubernetes/cmd/kubeadm/app/preflight"
 )
 
+type pferror struct{}
+
+func (p *pferror) Preflight() bool { return true }
+func (p *pferror) Error() string   { return "" }
 func TestCheckErr(t *testing.T) {
 	var codeReturned int
 	errHandle := func(err string, code int) {
@@ -35,7 +37,7 @@ func TestCheckErr(t *testing.T) {
 	}{
 		{nil, 0},
 		{fmt.Errorf(""), DefaultErrorExitCode},
-		{&preflight.Error{}, PreFlightExitCode},
+		{&pferror{}, PreFlightExitCode},
 	}
 
 	for _, rt := range tokenTest {