AttestoPhoenix.ClientIdMetadata.Cache.Ecto (AttestoPhoenix v0.10.0)

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Postgres-backed AttestoPhoenix.ClientIdMetadata.Cache for clustered deployments - CIMD (draft-ietf-oauth-client-id-metadata-document-01, IETF OAuth WG).

CIMD lets a client identify itself with no prior registration by using an HTTPS URL as its client_id; the authorization server dereferences that URL and validates the returned document. Caching the validated document keeps every authorization request from reaching out to the network. The default per-node AttestoPhoenix.ClientIdMetadata.Cache.ETS would re-fetch on each node and offers no coherence; this store persists each entry so a document fetched on one node is served from every node and the outbound fetch fan-out is bounded under load. It is the cache default for exactly the same reason the code/refresh/nonce/replay/PAR stores default to Ecto.

Only a validated document is ever written (the caller stores after Attesto.ClientIdMetadata.validate_document/2 succeeds, with an expires_at derived from the response's freshness directives clamped to the configured bounds); the draft (§6) and RFC 9111 forbid caching errors or malformed documents, so this store never validates and never sees an unaccepted document.

Behaviour callbacks

  • get/1 resolves a live (unexpired) cached document WITHOUT consuming it. Expiry is re-checked on read (expires_at > now), so an unswept expired row is a :miss, never a stale hit.
  • put/3 upserts the validated metadata and its expiry. A re-fetched document legitimately supersedes a stale one, so a conflicting url replaces the existing row's metadata and expires_at rather than failing - the freshest fetch wins.

Expired rows are reclaimed by AttestoPhoenix.Store.Sweeper, but sweeping is housekeeping only: get/1 already refuses an expired row.

The repository module is supplied by the host application (:repo under the :attesto_phoenix app) and read at call time; a cache with no backing repository fails closed rather than silently no-opping.

Summary

Functions

get(url)

Resolves a live cached document for a CIMD client_id URL.

put(url, metadata, expires_at)

Caches validated metadata for a CIMD client_id URL until expires_at.

Functions

get(url)

@spec get(String.t()) :: {:ok, map()} | :miss

Resolves a live cached document for a CIMD client_id URL.

Returns {:ok, metadata} when a row exists and has not expired, or :miss when it is absent or expired. metadata is round-tripped through jsonb, so the caller reads back the same string-keyed map it stored. Freshness is enforced on read (expires_at > now); resolution does not consume the entry, so it serves every request until it expires or is replaced.

put(url, metadata, expires_at)

@spec put(String.t(), map(), DateTime.t()) :: :ok

Caches validated metadata for a CIMD client_id URL until expires_at.

metadata is the validated, string-keyed map; it is round-tripped through jsonb. The url is the primary key, so a re-fetch upserts the single row: on conflict the stored metadata and expires_at are replaced with the freshly fetched values (the freshest accepted document wins), rather than raising or keeping a stale entry.