kubeadm: fix flaky-test TestManifestFilesAreEqual

cmd/kubeadm/app/util/staticpod/utils.go

@@ -29,8 +29,8 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/google/go-cmp/cmp"
 	"github.com/pkg/errors"
+	"github.com/pmezard/go-difflib/difflib"
 
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
@@ -374,7 +374,28 @@ func ManifestFilesAreEqual(path1, path2 string) (bool, string, error) {
 	if bytes.Equal(hash1, hash2) {
 		return true, "", nil
 	}
-	return false, cmp.Diff(pod2, pod1), nil
+
+	manifest1, err := kubeadmutil.MarshalToYaml(pod1, v1.SchemeGroupVersion)
+	if err != nil {
+		return false, "", errors.Wrapf(err, "failed to marshal Pod manifest for %q to YAML", path1)
+	}
+
+	manifest2, err := kubeadmutil.MarshalToYaml(pod2, v1.SchemeGroupVersion)
+	if err != nil {
+		return false, "", errors.Wrapf(err, "failed to marshal Pod manifest for %q to YAML", path2)
+	}
+
+	diff := difflib.UnifiedDiff{
+		A: difflib.SplitLines(string(manifest1)),
+		B: difflib.SplitLines(string(manifest2)),
+	}
+
+	diffStr, err := difflib.GetUnifiedDiffString(diff)
+	if err != nil {
+		return false, "", errors.Wrapf(err, "failed to generate the differences between manifest %q and manifest %q", path1, path2)
+	}
+
+	return false, diffStr, nil
 }
 
 // getProbeAddress returns a valid probe address.

cmd/kubeadm/app/util/staticpod/utils_test.go

@@ -766,18 +766,19 @@ func TestManifestFilesAreEqual(t *testing.T) {
 			podYamls:       []string{validPod, validPod2},
 			expectedResult: false,
 			expectErr:      false,
-			expectedDiff: string(`
-- 					"2",
-+ 					"1",`),
+			expectedDiff: `@@ -12 +12 @@
+-  - image: gcr.io/google_containers/etcd-amd64:3.1.11
++  - image: gcr.io/google_containers/etcd-amd64:3.1.12
+`,
 		},
 		{
 			description:    "manifests are not equal for adding new defaults",
 			podYamls:       []string{validPod, invalidWithDefaultFields},
 			expectedResult: false,
 			expectErr:      false,
-			expectedDiff: string(`
-- 		RestartPolicy:                 "Always",
-+ 		RestartPolicy:                 "",`),
+			expectedDiff: `@@ -14,0 +15 @@
++  restartPolicy: Always
+`,
 		},
 		{
 			description:    "first manifest doesn't exist",
@@ -830,7 +831,7 @@ func TestManifestFilesAreEqual(t *testing.T) {
 			}
 			if !strings.Contains(diff, rt.expectedDiff) {
 				t.Errorf(
-					"ManifestFilesAreEqual diff doesn't expected\n%s\n\texpected diff: %s\nactual diff: %s",
+					"ManifestFilesAreEqual diff doesn't expected\n%s\n\texpected diff: %s\n\tactual diff: %s",
 					rt.description,
 					rt.expectedDiff,
 					diff,