Note that subPathExpr uses round brackets.

bglimepoint · web-flow · commit ab9fdcbe24b9 · 2021-12-15T04:16:21.000Z
As it's easy to misread this as curly brackets for users familiar with
shell interpolation.
diff --git a/content/en/docs/concepts/storage/volumes.md b/content/en/docs/concepts/storage/volumes.md
@@ -1133,6 +1133,7 @@ spec:
     volumeMounts:
     - name: workdir1
       mountPath: /logs
+      # The variable expansion uses round brackets (not curly brackets).
       subPathExpr: $(POD_NAME)
   restartPolicy: Never
   volumes:
