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TODO.md

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+# TODO List
+
+- Improvement of path matcher
+- Option for rewriting path like
+  ```
+  https://example.com:8080/path/to -> http://backend:3030/any_path
+  ```
+  Currently, incoming path (`/path/to/`) is always preserved in the mapping process, i.e., mapped to `backend:3030/path/to`.
+- Smaller footprint of docker image using musl
+- Refactoring
+- Options to serve custom http_error page.
+- etc.