When VPP is running in the CSIT environment it has the api-trace feature enabled in the /etc/vpp/startup.conf

After every test run, the api-trace data needs to be saved as a binary file and archived with the test logs outside of the VM. The api-trace data is written to a binary file using the following VPP debug CLI command: "api trace save <filename>"
Note: <filename> will be saved in /tmp.

See https://wiki.fd.io/view/VPP/How_To_Use_The_API_Trace_Tools for more details on the use of api trace information.

If VPP crashes during a test run, then the api-trace data is automatically saved in the file: "/tmp/api_post_mortem.<PID>" After every test run, the /tmp directory should be searched for the existence of any api_post_mortem.* files which should be archived along with the rest of the log files outside of the VM and made available for diagnosing the crash.