prevent panic when the restore hook init container command annotation is empty (#10371)

* prevent panic when the restore hook init container command annotation is empty

Signed-off-by: samay43 <samayrbhat43@gmail.com>

* add changelog entry

Signed-off-by: samay43 <samayrbhat43@gmail.com>

---------

Signed-off-by: samay43 <samayrbhat43@gmail.com>
Co-authored-by: Daniel Jiang <daniel.jiang@broadcom.com>

changelogs/unreleased/10371-samay43

@@ -0,0 +1 @@
+prevent panic when the restore hook init container command annotation is empty

internal/hook/item_hook_handler.go

@@ -365,6 +365,12 @@ func getPodExecHookFromAnnotations(annotations map[string]string, phase HookPhas
 
 func parseStringToCommand(commandValue string) []string {
 	var command []string
+	// An empty command means the container image's own entrypoint should be used.
+	// Callers that require a command already return early; getInitContainerFromAnnotation
+	// deliberately allows this case, so return nil rather than indexing an empty string.
+	if commandValue == "" {
+		return nil
+	}
 	// check for json array
 	if commandValue[0] == '[' {
 		if err := json.Unmarshal([]byte(commandValue), &command); err != nil {

internal/hook/item_hook_handler_test.go

@@ -1287,6 +1287,25 @@ func TestGetInitContainerFromAnnotations(t *testing.T) {
 				podRestoreHookInitContainerCommandAnnotationKey: "[foobarbaz",
 			},
 		},
+		{
+			name:      "should use the image's default entrypoint when the command annotation is empty",
+			expectNil: false,
+			expected:  builder.ForContainer("restore-init1", "busy-box").Result(),
+			inputAnnotations: map[string]string{
+				podRestoreHookInitContainerImageAnnotationKey:   "busy-box",
+				podRestoreHookInitContainerNameAnnotationKey:    "restore-init",
+				podRestoreHookInitContainerCommandAnnotationKey: "",
+			},
+		},
+		{
+			name:      "should use the image's default entrypoint when the command annotation is missing",
+			expectNil: false,
+			expected:  builder.ForContainer("restore-init1", "busy-box").Result(),
+			inputAnnotations: map[string]string{
+				podRestoreHookInitContainerImageAnnotationKey: "busy-box",
+				podRestoreHookInitContainerNameAnnotationKey:  "restore-init",
+			},
+		},
 	}
 
 	for _, tc := range testCases {