openvoxdb does not reserve 5xx for its own faults: the same malformed
query is a 400 on /nodes and a 500 on /facts, and /metrics answers a flat
403, so a 4xx-only replay rule made pdbmux's behaviour depend on the
route. The meta and metrics handlers held their own copy of the gateway
error and bypassed the replay entirely.
- Replay any status from 400 up that every backend agreed on, with the
backend's own body and content type.
- Keep 502 for backends disagreeing on the status, or a backend that
answered nothing at all.
- Route /pdb/meta, /metrics and the pass-through path through the same
rule as the merged query handlers.
- Count a unanimous 5xx as a failed round and let it fall back to a stale
cache entry; only a unanimous 4xx stays exempt from both.
- Answer successful queries with openvoxdb's application/json;charset=utf-8.
Every backend gets the same query, so one they all refuse is the client's
mistake; flattening it into "all backends failed" threw openvoxdb's own
explanation away and logged a typo as an outage.
- Carry status, content type and body on a typed upstreamError
- Replay the status and explanation when every backend refuses alike
- Redact backend addresses from replayed bodies
- Keep a refused query out of the partial counters and the cache
unkin-agent