Dir mounting frenzy and Runtime enviroment script

[plasorak]

Mounting:

• DBT_INSTALL_DIR
• logs
• trace dir in the k8s pod.

And making use of the RTE script when provided (or trying to figure it out).

Unfortunately this requires a change in the configuration to work fully with k8s because the entry point is not correct :(

[plasorak]

So for a bit more context, what this is doing:

• if there is an RTE script setup in the boot.json, nanorc creates a command which sources it before executing daq_application
• If the RTE script isn't in boot.json, nanorc tries to figure it out and sources it in the same way.
• If the above fails, we go back to the old way of doing things (passing Nanorc's own environment to start the application)
• Nanorc strips the environment of LD_LIBRARY_PATH etc if RTE is found.
• Nanorc mounts a log path and trace path to be able to see these 2 directly for every application in the case of K8s (nanorc also uses tee for the daq_application logs, so that they are available in kubectl AND in the log file).

The RTE script stands for Run time environment script. It sets up all the environment (PATH, LD_LIBRARY_PATH, PYTHON_PATH and other DUNEDAQ specifics) to be able to execute daq_application. So it's like setting up your dbt_workarea_env and saving all your environment variables in a script.

[TiagoTAlves]

Tested this in conjunction with daqconf/plasorak/entrypoint and rte runs without the need for rte flag in the config file.