When watchtower detects that a running container needs to be updated it will stop the container by sending it a SIGTERM signal. If your container should be shutdown with a different signal you can communicate this to watchtower by setting a label named com.centurylinklabs.watchtower.stop-signal with the value of the desired signal.
This label can be coded directly into your image by using the
LABEL instruction in your Dockerfile:
Or, it can be specified as part of the
docker run command line:
docker run -d --label=com.centurylinklabs.watchtower.stop-signal=SIGHUP someimage