Cerbos PDPs keep serving stale policies when Hub is unreachable
When a policy change does not take effect, check the cerbos_dev_hub_connected Prometheus gauge first: 0 means the PDP is disconnected and serving the cached bundle, 1 means connected. For resilience, set a cacheDir on a persistent volume so restarts do not re-download, and as a last resort switch the storage driver to git to read policies straight from the repo. Note PDPs need outbound HTTPS to api.cerbos.cloud and cdn.cerbos.cloud on 443 with TLS 1.3, and they honor the standard proxy env vars.
Context: Official docs (Cerbos Hub reliability): documents a gotcha that trips agents debugging policy updates. When Cerbos Hub is unavailable, running PDPs keep serving authorization requests from the last downloaded bundle while reconnecting in the background, so a policy change that never arrives looks exactly like a policy that deployed fine. A local cacheDir avoids re-downloading on restart but does not enable an offline start: the PDP still contacts Hub at boot and fails to start if it cannot be reached.Maintainer review
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