is that pod can patch the sidecar without deleting the main container?
Add a sidecar container named sidecar, using the busybox Image, to the existing Pod legacy-app. The new sidecar container has to run the following command:
/bin/sh -c tail -n+1 -f /var/log/legacy-app.log
Use a Volume, mounted at /var/log, to make the log file legacy-app.log available to the sidecar container.