Stackdriver Trace is automatically enabled for all applications running on App Engine standard environment. App Engine standard environment applications do not require any additional instrumentation libraries or SDKs.
For setup in the App Engine flexible environment, see the following section, VMs or containers.
VMs or containers
Applications running on VMs or containers are not automatically traced. This includes VM instances from Compute Engine and App Engine flexible environment, and containers in Google Kubernetes Engine. Use the SDKs listed below, or the Stackdriver Trace API, to send traces to the service.
The Google Cloud Trace SDK for Java is available on GitHub:
The Stackdriver Trace SDK for Ruby is available on GitHub.
After deployment, you can view recorded traces and inspect the RPCs in your application.