* feat(kms): observe key lifecycle from the deletion sweep
The sweep already pages through the whole key set, so the lifecycle
gauges come out of the pages it has in hand: no extra backend call is
made for them. It publishes the number of keys awaiting their deletion
deadline, the number of tombstones an interrupted removal left behind,
and how long ago the least recently rotated usable key was rotated
(counting from creation for keys that were never rotated), plus a
per-outcome counter of what the sweep acted on.
Every gauge is a label-less aggregate: a per-key label would carry key
identifiers into the metric stream and grow the series count with the
key set, so "this key is overdue for rotation" stays a threshold for an
alerting rule to apply to the aggregate. Keys the sweep destroys drop
out of the census, and a sweep that could not finish listing leaves the
gauges at their last complete values rather than understating them.
* feat(kms): expose Vault token TTL and fail-closed state as gauges
The renewal loop already tracks token expiry, so it now publishes the
seconds left on the active Vault token and whether the provider is
refusing to serve it. The fail-closed gauge re-evaluates the very gate
`VaultCredentialProvider::current` applies, so what operators see and
what the request path does cannot drift apart.
Both waits in the loop republish on a bounded cadence, so a scrape
landing between refresh cycles never reads a TTL frozen at the last
refresh or a fail-closed state that flipped after it. That costs a timer
and no Vault traffic, and the request path stays free of metric work.
Renewal successes and failures already land in the auth operation
counters, so nothing is double-counted here. Neither gauge carries a
label: the address, mount, auth path and token are all off limits as
label values, and there is one generation to describe.
* feat(kms): add AppRole configuration surface for Vault auth
Extend VaultAuthMethod::AppRole with secret_id_file (re-read on every
login so external rotation is picked up), a configurable auth mount
(default "approle"), and an optional fail-closed safety window. All new
fields are serde(default) so previously persisted configurations keep
deserializing, and the strict admin-configure deserializer accepts them
as optional.
Environment selection: setting RUSTFS_KMS_VAULT_APPROLE_ROLE_ID switches
both Vault backends to AppRole; the secret_id comes from
RUSTFS_KMS_VAULT_APPROLE_SECRET_ID_FILE (path stored, file wins) or
RUSTFS_KMS_VAULT_APPROLE_SECRET_ID, following the static secret-key file
precedent. validate() rejects AppRole configs without a role_id, without
any secret_id source, or with an empty mount.
Also append the CredentialsUnavailable error variant used by the
fail-closed credential gate.
* feat(kms): implement AppRole login with background renewal and fail-closed expiry
Implement the AppRoleLogin token source (vaultrs approle login +
renew-self) and wire lease-bound credentials through the provider:
- Each successful login/renewal installs a new client generation in the
ArcSwap; in-flight requests finish on the generation they captured.
- A background renewal task refreshes at half the lease TTL: renewable
tokens are renewed in place, everything else (or a failed renewal)
falls back to a fresh login. Auth exchanges run under the typed retry
policy (OpClass::Auth) and failed cycles retry on a fixed cadence, so
the provider recovers once Vault does.
- Fail-closed: current() refuses to hand out a token inside the
configured safety window of its expiry (default: one attempt timeout),
returning CredentialsUnavailable instead of sending a request whose
token may lapse mid-flight.
- Refreshes are single-flight: concurrent triggers for the same
generation coalesce into one login.
- The renewal task's owner handle lives on the KMS service version:
stop() shuts it down explicitly and reconfigure recycles it via
cancel-on-drop when the old version is discarded.
- The secret_id file is re-read on every login attempt; missing or empty
files fail the attempt without contacting Vault. Crate-owned copies of
tokens and secret_ids are zeroized on drop, and Debug output of every
credential-carrying type stays redacted (leak regression tests).
The renewal machinery is covered by paused-clock tests driving a
scripted token source: renew-at-half-TTL timing, login fallback,
fail-closed window entry and recovery, prompt task recycling, and
coalesced concurrent refreshes.
* feat(kms): add Vault Agent token file authentication
Add the TokenFile source: the token is read from an agent-managed sink
file (RUSTFS_KMS_VAULT_TOKEN_FILE or the TokenFile auth config) and
re-read once per poll interval (default 30s) through the existing
renewal loop, so a token rotated by the agent installs a new client
generation within one poll of the atomic replace. Each successful read
extends the token's observed validity to twice the poll interval; a
file that disappears or turns empty keeps failing the refresh until the
fail-closed window trips, and heals the provider as soon as it is
restored.
Reads are strict and never contact Vault on failure: the file must be
non-empty after trimming, and on Unix group/other permission bits are a
hard error (mirroring the SFTP host-key rule). Rotation detection uses
a content digest; the token itself is never stored on the source and
the crate-owned copy is zeroized.
Configuring the token file together with AppRole or an explicit static
token is rejected as a configuration error. All new config fields are
serde(default) and the strict admin-configure deserializer accepts the
new variant.
Covered by paused-clock tests (atomic replacement installs a new
generation next cycle, deletion fails closed and recovers, prompt task
recycling) plus negatives for missing/empty/over-permissive files and a
Debug leak regression.
* docs(kms): add Vault authentication and credential lifecycle runbook
Cover choosing between static token, AppRole, and Vault Agent token
file auth; AppRole role setup with SecretID delivery and rotation;
Agent sink deployment with the permission requirements; and the
fail-closed window semantics with a troubleshooting table keyed on the
renewal task's log lines.
* fix(kms): repair vault test call sites missed by the timeout refactor
Three offline tests still constructed VaultKmsClient with the pre-#5472
single-argument signature, leaving cargo test -p rustfs-kms unable to
compile. Pass the same 30s attempt timeout the neighbouring tests use.
* refactor(kms): route Vault clients through a rotatable credential provider
Both Vault backends previously built a VaultClient in their constructor
and held it for the lifetime of the backend, which leaves no seam for
re-authentication: rotating credentials would require tearing down the
whole backend.
Introduce backends/vault_credentials with a TokenSource trait (only
StaticToken for now; AppRole login and agent token files land in
follow-ups) and a VaultCredentialProvider that owns the authenticated
client behind an ArcSwap. Request paths take a per-call snapshot via
current(), so a future rotation swaps in a new client generation without
interrupting calls already in flight. Tokens held by this crate are
zeroized on drop, and Debug output of every credential-carrying type is
redacted (covered by a leak regression test).
Behavior is unchanged: static token, namespace, and per-attempt timeout
feed the same VaultClientSettings as before, and AppRole configurations
are still rejected at construction with the same message.
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