kubeadm: fix runtime.ImageExists API

This API return error when underlying 'inspect' command
fails. This makes ImagePullCheck to fail as it doesn't expect
runtime.ImageExists to return an error even if image doesn't exist.

Fixed this by returning error nil even when inspect command fails.

cmd/kubeadm/app/preflight/checks_test.go

@@ -701,14 +701,24 @@ func TestSetHasItemOrAll(t *testing.T) {
 
 func TestImagePullCheck(t *testing.T) {
 	fcmd := fakeexec.FakeCmd{
+		RunScript: []fakeexec.FakeRunAction{
+			// Test case 1: img1 and img2 exist, img3 doesn't exist
+			func() ([]byte, []byte, error) { return nil, nil, nil },
+			func() ([]byte, []byte, error) { return nil, nil, nil },
+			func() ([]byte, []byte, error) { return nil, nil, &fakeexec.FakeExitError{Status: 1} },
+
+			// Test case 2: images don't exist
+			func() ([]byte, []byte, error) { return nil, nil, &fakeexec.FakeExitError{Status: 1} },
+			func() ([]byte, []byte, error) { return nil, nil, &fakeexec.FakeExitError{Status: 1} },
+			func() ([]byte, []byte, error) { return nil, nil, &fakeexec.FakeExitError{Status: 1} },
+		},
 		CombinedOutputScript: []fakeexec.FakeCombinedOutputAction{
-			func() ([]byte, error) { return nil, nil }, // Test case 1
+			// Test case1: pull only img3
-			func() ([]byte, error) { return nil, nil },
-			func() ([]byte, error) { return nil, nil },
-			func() ([]byte, error) { return []byte("error"), &fakeexec.FakeExitError{Status: 1} }, // Test case 2
-			func() ([]byte, error) { return nil, nil },
 			func() ([]byte, error) { return nil, nil },
+			// Test case 2: fail to pull image2 and image3
 			func() ([]byte, error) { return nil, nil },
+			func() ([]byte, error) { return []byte("error"), &fakeexec.FakeExitError{Status: 1} },
+			func() ([]byte, error) { return []byte("error"), &fakeexec.FakeExitError{Status: 1} },
 		},
 	}
 
@@ -721,6 +731,9 @@ func TestImagePullCheck(t *testing.T) {
 			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
 			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
 			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
+			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
+			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
+			func(cmd string, args ...string) exec.Cmd { return fakeexec.InitFakeCmd(&fcmd, cmd, args...) },
 		},
 		LookPathFunc: func(cmd string) (string, error) { return "/usr/bin/docker", nil },
 	}
@@ -746,7 +759,7 @@ func TestImagePullCheck(t *testing.T) {
 	if len(warnings) != 0 {
 		t.Fatalf("did not expect any warnings but got %q", warnings)
 	}
-	if len(errors) != 1 {
+	if len(errors) != 2 {
-		t.Fatalf("expected 1 errors but got %d: %q", len(errors), errors)
+		t.Fatalf("expected 2 errors but got %d: %q", len(errors), errors)
 	}
 }

cmd/kubeadm/app/util/runtime/runtime.go

@@ -172,18 +172,12 @@ func (runtime *DockerRuntime) PullImage(image string) error {
 
 // ImageExists checks to see if the image exists on the system
 func (runtime *CRIRuntime) ImageExists(image string) (bool, error) {
-	out, err := runtime.exec.Command("crictl", "-r", runtime.criSocket, "inspecti", image).CombinedOutput()
+	err := runtime.exec.Command("crictl", "-r", runtime.criSocket, "inspecti", image).Run()
-	if err != nil {
+	return err == nil, nil
-		return false, fmt.Errorf("output: %s, error: %v", string(out), err)
-	}
-	return true, nil
 }
 
 // ImageExists checks to see if the image exists on the system
 func (runtime *DockerRuntime) ImageExists(image string) (bool, error) {
-	out, err := runtime.exec.Command("docker", "inspect", image).CombinedOutput()
+	err := runtime.exec.Command("docker", "inspect", image).Run()
-	if err != nil {
+	return err == nil, nil
-		return false, fmt.Errorf("output: %s, error: %v", string(out), err)
-	}
-	return true, nil
 }

cmd/kubeadm/app/util/runtime/runtime_test.go

@@ -266,15 +266,15 @@ func TestPullImage(t *testing.T) {
 
 func TestImageExists(t *testing.T) {
 	fcmd := fakeexec.FakeCmd{
-		CombinedOutputScript: []fakeexec.FakeCombinedOutputAction{
+		RunScript: []fakeexec.FakeRunAction{
-			func() ([]byte, error) { return nil, nil },
+			func() ([]byte, []byte, error) { return nil, nil, nil },
-			func() ([]byte, error) { return []byte("error"), &fakeexec.FakeExitError{Status: 1} },
+			func() ([]byte, []byte, error) { return nil, nil, &fakeexec.FakeExitError{Status: 1} },
-			func() ([]byte, error) { return nil, nil },
+			func() ([]byte, []byte, error) { return nil, nil, nil },
-			func() ([]byte, error) { return []byte("error"), &fakeexec.FakeExitError{Status: 1} },
+			func() ([]byte, []byte, error) { return nil, nil, &fakeexec.FakeExitError{Status: 1} },
 		},
 	}
 	execer := fakeexec.FakeExec{
-		CommandScript: genFakeActions(&fcmd, len(fcmd.CombinedOutputScript)),
+		CommandScript: genFakeActions(&fcmd, len(fcmd.RunScript)),
 		LookPathFunc:  func(cmd string) (string, error) { return "/usr/bin/crictl", nil },
 	}
 
@@ -282,7 +282,7 @@ func TestImageExists(t *testing.T) {
 		name      string
 		criSocket string
 		image     string
-		isError   bool
+		result    bool
 	}{
 		{"valid: test if image exists using CRI", "unix:///var/run/crio/crio.sock", "image1", false},
 		{"invalid: CRI inspecti failure", "unix:///var/run/crio/crio.sock", "image2", true},
@@ -298,14 +298,8 @@ func TestImageExists(t *testing.T) {
 			}
 
 			result, err := runtime.ImageExists(tc.image)
-			if result && err != nil {
+			if !tc.result != result {
-				t.Errorf("unexpected ImageExists result %v and error: %v", result, err)
+				t.Errorf("unexpected ImageExists result: %t, criSocket: %s, image: %s, expected result: %t", err, tc.criSocket, tc.image, tc.result)
-			}
-			if !tc.isError && err != nil {
-				t.Errorf("unexpected ImageExists error: %v, criSocket: %s, image: %s", err, tc.criSocket, tc.image)
-			}
-			if tc.isError && err == nil {
-				t.Errorf("unexpected ImageExists success, criSocket: %s, image: %s", tc.criSocket, tc.image)
 			}
 		})
 	}