We'd like to monitor the number of documents in a collection via DataDog.

For On-Premise MongoDB the stats are already reported via mongodb.collection.count, mongodb.collection.size and mongodb.collection.avgobjsize.

If the same metrics could be made available for Atlas (E.g. mongodb.atlas.stats.collection.count) that would really help in monitoring.

E.g. spikes in different parts of the application could be tied to the number of documents on a glance. Without having that metric available, it is hard to pinpoint if a recent change had a negative impact on performance.

If the metrics can't be made available on the collection but only on the database level, this would already be helpful as well.