Merge pull request #25800 from ingvagabund/mounttest-use-stats-instead-of-lstat-to-read-symlinks

Automatic merge from submit-queue

gcr.io/google_containers/mounttest: use Stat instead of Lstat

The current ``mt.go`` implementation use ``os.Lstat`` instead of ``os.Stat`` which does not read symlinks. Since implementation of ``AtomicWriter`` (which relies on existence of symlinks), the updated implementation of secret volume using the ``AtomicWriter`` can not be tested for secret file permission. Replacing ``Lstat`` with ``Stat`` allows to read symlinks and return permissions of target file. The change affects ``--file_perm`` and ``--file_mode`` options only.

``mounttest`` image is currently used by:

##### downwardapi_volume.go
- e2e: Downward API volume
- version: 0.6
- args: --file_content, --break_on_expected_content, --retry_time, --file_content_in_loop

##### empty_dir.go
- e2e: EmptyDir volumes
- version: 0.5
- args: --file_perm, --file_perm, ...

##### host_path.go
- e2e: hostPath
- version: 0.6
- args: --file_mode, ...

##### configmap.go
- e2e: ConfigMap
- version: 0.6
- args: --file_content, --break_on_expected_content, --retry_time, --file_content_in_loop

##### service_accounts.go
- e2e: ServiceAccounts
- version: 0.2
- args: --file_content

Some of the e2e tests use at least one of the affected options. Locally, I have updated all version of mounttest images to 0.7. All e2e tests pass with the new image.

test/images/mount-tester/Makefile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-TAG = 0.6
+TAG = 0.7
 PREFIX = gcr.io/google_containers
 
 all: push

test/images/mount-tester/mt.go

@@ -162,9 +162,9 @@ func fileMode(path string) error {
 		return nil
 	}
 
-	fileinfo, err := os.Lstat(path)
+	fileinfo, err := os.Stat(path)
 	if err != nil {
-		fmt.Printf("error from Lstat(%q): %v\n", path, err)
+		fmt.Printf("error from Stat(%q): %v\n", path, err)
 		return err
 	}
 
@@ -177,9 +177,9 @@ func filePerm(path string) error {
 		return nil
 	}
 
-	fileinfo, err := os.Lstat(path)
+	fileinfo, err := os.Stat(path)
 	if err != nil {
-		fmt.Printf("error from Lstat(%q): %v\n", path, err)
+		fmt.Printf("error from Stat(%q): %v\n", path, err)
 		return err
 	}