Announcing 2.3.0 of libbson and libmongoc, the libraries constituting the MongoDB C Driver.

libbson

Improvements

bson_append_array_begin. Use bson_append_array_builder_begin or bson_append_array_unsafe_begin instead.

Added support for MongoDB's Intelligent Workload Management (IWM) and ingress connection rate limiting features. The driver now gracefully handles write-blocking scenarios and optimizes connection establishment during high-load conditions to maintain application availability.
- Supported on all commands.
- Custom application retry logic may need to be adjusted to avoid retrying too long.
- Upgrade is recommended to avoid impacts of server changes related to overload errors.
  - If not upgrading, custom application retry logic may need to be adjusted to handle higher rates of overload errors. See Overload Errors.
- Add URI option maxAdaptiveRetries to configure the maximum number of retries for operations that fail with a SystemOverloadedError (default: 2).
- Add URI option enableOverloadRetargeting to control whether retries of SystemOverloadedError will attempt to use a different server (default: false).
Support appending client handshake metadata after initialization and per-client/pool.
- Adds mongoc_client_append_metadata and mongoc_client_pool_append_metadata.
- Useful for projects wrapping the C driver to self-identify.
Support Kubernetes as a credential provider for MONGODB-OIDC authentication.

Improve cursor handling on client-side timeouts:
- Send killCursors after cursor receives client-side timeout.
- Break early if change stream resumes on repeated client-side timeouts.

Support for macOS versions 13 and older. These versions are EOL and not tested. Use macOS version 14 or newer.