If monitoring data is not available in Dynatrace despite the dynatrace-oneagent being in "Running" status, what could be the cause?

The situation where monitoring data is not available in Dynatrace, even though the Dynatrace OneAgent is running, can often be attributed to specific scenarios regarding the timing of application container startup relative to OneAgent installation. When application containers are started before the OneAgent is installed, it prevents the OneAgent from being able to collect monitoring data from those containers. This is because the OneAgent needs to be in place before the application components are initialized in order to hook into the process and gather the necessary telemetry.

In contrast, if the OneAgent installation were faulty, or if the Dynatrace configuration were incorrect, these issues would likely result in the OneAgent not being able to start at all or manifest in errors during operation. Similarly, while a lost network connection can affect data transmission, it wouldn’t completely prevent data from being collected as long as the OneAgent is running and has started before data collection occurs. Hence, the timing of when containers are initiated relative to the installation of the OneAgent is the critical factor for ensuring monitoring data availability.