* Add OAuth M2M support for A2A agents targeting Databricks Apps
Databricks App endpoints reject static bearer tokens and require a
short-lived OAuth token minted via the workspace OIDC token endpoint.
A2A agents could previously only authenticate outbound with static_headers
or client header passthrough, so Databricks App agents could not be
registered.
Agents configured with a databricks_oauth block in litellm_params now mint
and cache a client_credentials token and attach it as the outbound
Authorization header on both message/send and message/stream calls,
overriding any statically configured Authorization.
* Add tests covering Databricks App OAuth token error paths
Cover the HTTP status error, transport error, non-object JSON body, and
invalid expires_in fallback branches in the token cache so the failure
handling is locked in by regression tests.
* Harden Databricks App OAuth token cache
Cap the cache TTL at the token's own lifetime so a token whose validity is
shorter than the refresh buffer is never cached and served stale; include a
digest of client_secret in the cache key so a rotated secret mints a fresh
token instead of reusing the old one; and prune the per-key lock when its
cached token is evicted so the lock map stays bounded by the live key set.
* Clear per-key locks on Databricks OAuth cache flush
* fix(a2a/databricks): mint OAuth token via Basic auth header, not unsupported auth= kwarg
litellm's AsyncHTTPHandler.post (what get_async_httpx_client returns) has no
auth parameter, so minting a Databricks App OAuth token raised
"AsyncHTTPHandler.post() got an unexpected keyword argument 'auth'" before any
network call ever left the proxy, breaking the feature end to end. The handler
also calls raise_for_status() internally and re-raises a MaskedHTTPStatusError
(a subclass of httpx.HTTPStatusError), so the explicit raise_for_status() after
post() was dead code.
Build the HTTP Basic Authorization header by hand and pass it via headers, which
is what the Databricks workspace OIDC token endpoint documents for client
authentication. The token-cache tests now model the real handler contract with
create_autospec so the rejected auth= signature is enforced; the previous mocks
accepted any kwargs and silently hid the bug.
Co-authored-by: Mateo Wang <mateo-berri@users.noreply.github.com>
* Prune Databricks OAuth lock on the short-lived-token path
When expires_in is below the refresh buffer the token is intentionally
not cached, so _remove_key never runs for that key and the per-key lock
created by _get_lock leaked permanently. Drop the lock in that branch so
_locks stays bounded by the live key set, and assert the cleanup in the
short-lived-token test
* Gate A2A Databricks OAuth on the databricks_oauth block at the call site
Make the gating explicit where the header is applied so it is clear that only
agents configured with a databricks_oauth block enter the OAuth path; every
other agent is left untouched. Add a regression test asserting a non-Databricks
agent never invokes the token resolver.
---------
Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Mateo Wang <mateo-berri@users.noreply.github.com>
778a7f752d