chi.lease.create_lease does not document error behavior

[robertu94]

Hi, thanks again for the chi library. It simplifies things alot relative to the raw underlying openstack python commands I used a few years ago, but one issue I hit was chi.lease.create_lease does not document what happens when the requested resources are exhausted. Trying this function in an error condition, it returns None and prints a log message. While this is a decent C error reporting mechanism; and I do appreciate the improved error message relative the blazarclient message that is caught below, it is kind of an unexpected way to indicate an error in Python where exceptions are generally preferred (c.f. "Errors should never pass silently" - The Zen of Python). Perhaps instead of logging and returning None, you could perhaps instead use

raise RuntimeError(what_you_log_right_now) from blazar_exception

If you don't want to do this, please at least document the error handling for this routine.

[BNNARAJ]

I would like to work on this issue. I go through the lease.py and came across the underlying issue for the Resource Exhaustion error and my idea is that we can change in the exception block to handle and report the error in more improved manner.

except BlazarClientException as ex:
if 'not enough resources' in ex.args[0].lower():
raise ResourceExhaustionError(f"Lease creation failed: Insufficient resources") from ex
else:
# Handle other BlazarClientException types (optional)
LOG.error(f"Error creating lease: {ex}")
return None

in this we can raile a error for the specific issue of ResourceExhaustionError.
Allow me to comunicate with you @robertu94 to for any problem with this idea so that I can make a PR.