server restart v1

[JunAishima]

• use EPICS to trigger a PV
  • GUI button to be restored, mechanism to be poking this PV (value unimportant)
• use a kafka triggering system underneath
  • eventually to replace the PV when we have a Kafka-compatible conda environment for the LSDC GUI and server
  • channel name: {beamline.lower}.lsdc.serverRestartSignal ?
• on server host, have a service that monitors the PV
  • restart server using normal mechanism when the message is received
  • ownership - may be problematic. register script to be root?
  • consideration - what if it is not running already? who would it start it as?
  • more straightforward if owned by beamline staff - just start a new one as them

[JunAishima]

feedback: naming of scripts is not scientist-friendly. some issues with the documentation, including the precise PVs involved (when testing things manually)

but it does work!

Edit: look at https://github.com/NSLS-II/mx-scripts for pv_to_kafka.py and kafka_to_restart.py which are the guts of the system. In LSDC, the change to LSDC GUI, https://github.com/NSLS-II/lsdc/commit/36f5ad2f4e233dbf25aa77ae196e7feb00639f94, is how the user can trigger the change.