Open Stack

Hi everyone,

Recently, there are many emails to discuss a topic that "Why are projects trying to avoid Barbican, still?" [0]. That is very an interesting topic. Now I would like to make a new topic related to Rolling upgrade. I am trying to find  information about the strategy to support rolling-upgrade for Barbican project. Unfortunately, there is not any results, if any, could you please update it for me. 

In my point of view, in order to support this feature, there will be three impacts which need to solve:

1. API versioning:

Maybe, Barbican will have version two [1] so I think we should have a plan to still support version 1 on version 2. What do you about this point?

2. Database

- For OVO (Oslo version object) [2], I am wondering we should use OVO for this project. In my option, I am afraid that OVO is overkill for this project.
- For DB upgrading, currently there are some files [3-4] to drop and alter column. This really should not have because there is not still have a solution in case of delete or alter DB. That why there is a rule that don't allow somebody to delete/alter DB in Nova and Neutron :) Do you think we should prepare for this?

3. RPC

There is not version parameter when sending AMQP [5]. This parameter is really necessary to distinguish the message is Ocata or Pike.   

That is some points in my option, what do you think we should have to plan to support this feature and I am very glad to discuss this topic with you on this thread mailing-list. 

[0] http://lists.openstack.org/pipermail/openstack-dev/2017-January/thread.html#110192 
[1] https://wiki.openstack.org/wiki/Barbican/v2 
[2] https://www.slideshare.net/davanum/ovo-deep-dive 
[3] https://github.com/openstack/barbican/blob/master/barbican/model/migration/alembic_migrations/versions/3041b53b95d7_remove_size_limits_on_meta_table_values.py 
[4] https://github.com/openstack/barbican/blob/master/barbican/model/migration/alembic_migrations/versions/254495565185_removing_redundant_fields_from_order.py 
[5] https://github.com/openstack/barbican/blob/master/barbican/queue/client.py#L49 

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Best Regard,

Nam NH
OpenStack team