MongoDB Enterprise includes an auditing capability for
mongos instances. The auditing
facility allows administrators and users to track system activity for
deployments with multiple users and applications.
For information on the audit log messages, see System Event Audit Messages.
Once enabled, the auditing system can record the following operations :
replica set and sharded cluster,
authentication and authorization, and
CRUD operations (requires
For details on audited actions, see Audit Event Actions, Details, and Results.
|Operations in an aborted transaction still generate audit events. However, there is no audit event that indicates that the transaction aborted.
The auditing system writes every audit event  to an in-memory buffer of audit events. MongoDB writes this buffer to disk periodically. For events collected from any single connection, the events have a total order: if MongoDB writes one event to disk, the system guarantees that it has written all prior events for that connection to disk.
If an audit event entry corresponds to an operation that affects the durable state of the database, such as a modification to data, MongoDB will always write the audit event to disk before writing to the journal for that entry.
That is, before adding an operation to the journal, MongoDB writes all audit events on the connection that triggered the operation, up to and including the entry for the operation.
These auditing guarantees require that MongoDB run with
MongoDB may lose events if the server terminates before it commits the events to the audit log. The client may receive confirmation of the event before MongoDB commits to the audit log. For example, while auditing an aggregation operation, the server might terminate after returning the result but before the audit log flushes.
In addition, if the server cannot write to the audit log at the
audit destination, the server
|Audit configuration can include a filter to limit events to audit.