readonly-ui-proxy

A read-only proxy in front of the Restate admin API (default port 9070). It lets the Restate UI load and browse everything, but blocks every mutating operation.

How it works

The proxy is a method + path whitelist (default-deny):

• GET / HEAD on any path — the UI is served from the admin port and all its read APIs are GET.
• POST /query — the SQL introspection endpoint the UI uses for most reads. The engine has DDL/DML disabled (verified per query plan) and is built without file/object-store functions, so it can't write or read host files.
• Optionally POST .../serdes/{decode,encode}/... — side-effect-free payload (de)serialization, needed to render binary payloads on Restate >= 1.7.0. Off by default.
• Everything else — 403.

This works because every mutating endpoint in the admin API is either POST on a non-/query path (register deployment, modify service state, bulk invocation ops, ...) or PATCH/PUT/DELETE. A GET + POST /query whitelist catches them all — a verb blacklist would miss the POST-based mutations.

Implementation via NGINX reverse proxy.

nginx-proxy/ — an nginx config + a Docker script for quick local testing.

Caveats

• The whitelist also allows any other GET the server exposes (e.g. the raw metadata store, if the server was built with the non-default metadata-api feature). That's still read-only; restrict GET by path if you want to hide it.
• Add TLS / auth in front if the proxy is exposed beyond localhost — it does neither.