A remote created through the API without `mutable_ttl` was stored as 0, so its mutable paths never refreshed. With `check_mutable`, the ETag expired together with the freshness key, so an expired mutable path was always refetched in full and never revalidated.
- default an omitted `mutable_ttl` to 3600 on create; keep the stored value on update; explicit 0 still means never expire
- keep mutable ETags for `max(10 × mutable_ttl, 7d)`, re-armed on each 304, only when `check_mutable` is set and `mutable_ttl` is non-zero
- drop the stored ETag when a refetch returns none; never store one for immutable paths
- flush a remote's Redis keys on delete
- update docs/common/caching.md
Reviewed-on: #151
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>
## Why
Switching a remote's backend (`base_url`) left artifactapi serving the previously-cached mutable metadata (repodata / Release / APKINDEX) until TTL expiry, so requests could keep pointing at the old upstream. `cache.FlushRemote` already existed but was wired to nothing.
## How
- Inject a `MetadataFlusher` (satisfied by `*cache.Redis`) into `RemotesHandler` via `NewRemotesHandler`; `server.go` passes `s.cache`.
- On update, read the existing remote first, then after a successful DB update flush the remote's cached metadata when `base_url` changed, so the next request re-fetches fresh from the new upstream.
- Keep scope to `base_url` (upstream identity); a flush failure is logged as a warning and does not fail the request since the DB update already landed.
- Add tests: a `base_url` change flushes exactly once, an unchanged `base_url` does not flush, and a flush error still returns 200.
Reviewed-on: #120
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>
unkin-agent