* feat(kms): record real cache hit, miss and eviction metrics
The metadata cache reported (entry_count, 0) because moka exposes no hit
or miss counts, so the miss half of every cache report was a constant.
Track lookups and removals in the cache itself: hit/miss counters on the
lookup path, a moka eviction listener classifying removals by cause, and
an entry gauge refreshed whenever the entry set changes. The counters are
exported through the metrics facade under the rustfs_kms_ prefix with
static label values only, matching the operation-policy metrics, and are
also returned as a KmsCacheStats snapshot in place of the old tuple.
Cache semantics are unchanged: capacity, TTL and invalidation points are
the same, and remove now flushes pending maintenance so the gauge and the
removal notification describe the cache the caller sees.
Refs rustfs/backlog#1584
* fix(kms): report real cache counters through the admin status API
KmsStatusResponse.cache_stats mapped the old (entry_count, 0) tuple onto
hit_count and miss_count, so operators polling KMS status read the entry
count as a hit count and a miss count that was always zero.
Map the fields to the counters they claim to be, and add entry_count and
eviction_count as additive, defaulted fields so the entry number that
hit_count used to carry is still available.
Refs rustfs/backlog#1584
* fix(kms): refresh the cache entry gauge on lookup misses
The entry gauge was published only from the write paths, so an entry
dropped by TTL expiry left `rustfs_kms_metadata_cache_entries` reporting
a population that no longer existed until the next put, remove or clear.
A cache that goes quiet — entries ageing out with no further writes —
kept over-reporting indefinitely.
Republish the gauge from the lookup path when the lookup misses. A miss
is where expiry surfaces, and moka reaps expired entries in the
maintenance it runs during that same lookup, so the count read
afterwards reflects the reaping. Hits stay free of the extra work.
* docs(kms): correct the entry gauge convergence claim on the miss path
The comment on the miss-path gauge refresh said moka reaps expired
entries in the maintenance it runs on that same lookup. It does not:
`should_apply_reads` is gated on a full read log or an elapsed
housekeeping interval, so the removal that decrements `entry_count` and
reaches the eviction listener may land on a later lookup.
The behaviour and the test are unchanged — the gauge still converges,
and the test drives `run_pending_tasks` explicitly rather than riding on
that interval. Only the stated guarantee was wrong, so say interval
instead of same-lookup and record why forcing maintenance on the read
path was not the trade taken.
* feat(kms): implement secure handling of static KMS secret keys and enhance encryption context validation
* feat: enhance local SSE DEK handling with JSON envelope format and versioning
Zhengchao An