Allow specifying whether to unconditionally kill containers, or first send SIGTERM

[CameronDiver]

context: balena-os/balena-supervisor#1079

Currently livepush will always send a SIGKILL to restart the container, for speed, but some applications require being able to catch a signal to clean up before exiting. This should just be an option which says either kill first, otherwise use docker stop to respectfully wait for the container to finish.

[balena-ci]

[karaxuna] This issue has attached support thread https://jel.ly.fish/#/support-thread~692cfd3b-8303-4383-9dc4-7c528cb198f8

[hpgmiskin]

Hi @CameronDiver, have there been any recent updates on this? I am not able to access Jellyfish and would really appreciate the ability for live push to allow the program to do a graceful shutdown.

[pdcastro]

@hpgmiskin, I don't think there were any updates. I have created a balena CLI issue (balena-io/balena-cli#2162) to increase visibility of the problem - thanks for re-surfacing it.