The Datadog cartridge allows users to monitor their OpenShift v2 gears in one place, collecting metrics from the gear and any other servers running on-premise or in cloud environments. The cartridge is designed to work with OpenShift v2 gears, but can also be used to instrument OpenShift v3 apps to send custom metrics using a standalone image. Datadog collects system metrics from the gear and makes them available for graphing and alerting, allowing users to set up alerts on specific metrics or tags. The cartridge supports scalable and non-scalable apps, automatically scaling monitoring with the application. Users can install the cartridge on their gears and collect metrics from their apps, using a step-by-step installation process that requires an OpenShift v2 app, the OpenShift RHC client tool, and a Datadog account.