Blazar should allow updating or removing extra capability key/value pairs

[Pierre Riteau]

Currently, Blazar allows users to add extra capabilities (as a key/value pair) to a host while creating or updating it, but doesn't allow updating the value or removing the key/value pair.

This will require changes to the Blazar service (and maybe to the API?) and to the command-line client.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/491583
Committed: https://git.openstack.org/cgit/openstack/blazar/commit/?id=03e005993262357eb955601fb8acef38654eadf8
Submitter: Jenkins
Branch: master

commit 03e005993262357eb955601fb8acef38654eadf8
Author: Pierre Riteau <email address hidden>
Date: Fri Aug 11 09:20:04 2017 +0100

    Allow update host API to add new extra capabilities

    The update host API can only update existing extra capabilities.
    However, we can support adding new extra capabilities to hosts without
    API change.

    With this patch, Blazar can both create and update extra capabilities
    via the update host API.

    Partial-Bug: #1674524
    Change-Id: Ic9bd743a1c31858db9390a3379dc19e1e54327a8

[Masahito Muroi (muroi-masahito)]

Partial bug fix, supporting update extra capacity, was released in Pike. The concrete bug fix or discussions about supporting update/delete or not is targeted to Queens release.

[Hiroaki Kobayashi (hiro-kobayashi)]

Updating or deleting of extra capabilities can break a lease. For example, the following scenario can happen:

1. A user create a lease including a host reservation with 'sample-excap=true'.
2. Then, a hostA which has 'sample-excap=true' in it's extra capability is reserved.
3. After that, the sample-excap is removed from the extra capability of the hostA.
4. Though the hostA does not satisfy 'sample-excap=true', it's still reserved for the user.

So, before updating or deleting extra capabilities, blazar should check if it breaks existing leases.

[Masahito Muroi (muroi-masahito)]

Based on the discussion in the Dublin PTG, host API will support PATCH update.