Create leases with lease duration instead of end date

[Pierre Riteau]

It would be useful to be able to run:

    blazar lease-create --duration 2h

which would create a lease starting "now" and ending at now+2h. Currently only +24h is possible without giving any date argument.

It could be combined with a start date as well:

    blazar lease-create --start-date "2050-01-01 00:00" --duration 2h

[Pierre Riteau (priteau)]

There was discussion at the Stein PTG about this approach: support in client vs support in API. Pierre will prepare a client-side patch and we will continue the discussion on Gerrit.

[Asmita Singh (asmita2018)]

support in client vs support in API

Support in client:-
If we add support in client, then there is below issue.

If 'start-date' is not given then considered as 'now'
here in pythonclient. The actual start value is set in
the blazar api service. Considering this point, the end_time
is not exactly as it would be expected.

Support in API:-

So IMO, since we are supporting microversion in https://review.opendev.org/#/c/655837
(Add microversion support), we can handle 'lease duration' by bumping microversion at Blazar API side.

Kindly confirm.