Hello folks!!

We are facing some trouble with DataDog dd-trace-rb and out MongoDB integration from a Ruby service we operate.

We are running MongoDB Server 3.4, MongoDB Ruby client version 2.4 and dd-trace-rb version 1.9.0. The situation is as follows:

1. We want to upgrade to a newer MongoDB Server version (e.g. 3.6 and above) because MongoDB Server 3.4 end-of-life-support ends on September 2019
2. We need a newer MongoDB Ruby client driver (>=2.5) to have full compatibility with MongoDB Server 3.6 and above.
3. This gem dd-trace-rb 1.9.0 (but also apparently in latest version 0.21.0) supports MongoDB Ruby client driver up to version 2.4, so upgrading MongoDB Ruby client driver to a newer version would break DataDog APM integration.

We tried the upgrade anyways, and we have seen APM spans are lost on the integration of our service with MongoDB server, loosing a lot of visibility. MongoDB Server 3.4 support end-of-life ends in September 2019 (6 months from now).

This ticket aims to make this issue more visible to other MongoDB-from-ruby users and gather advice/support for other folks suffering this issue. In parallel I've opened a official support ticket with DataDog to see what alternatives we have.