[openstack-dev] [nova] Suggest to not deprecate os-migrations API

Sean Dague sean at dague.net
Tue May 24 12:46:40 UTC 2016

On 05/23/2016 10:16 PM, Zhenyu Zheng wrote:
> Hi All,
> According
> to https://github.com/openstack/nova/blob/master/releasenotes/notes/os-migrations-ef225e5b309d5497.yaml
> , we are going to deprecate the old os-migrations API, and two new APIs:
> /servers/{server uuid}/migrations and /servers/{server
> uuid}/migrations/{migration id} is added.
> As we can see, the newly added APIs cannot work if we don't know which
> instance is migrating. If our user uses HA applications or DRS
> applications such as openstack-watcher, automatic migrations can take
> place, we may not know which instance is migrating. And an API like the
> old os-migrations will be a really good choice to use, we can get all
> the current running migrations in simply one call. So I suggest not
> deprecate this API.
> Any thoughts?

If watcher is migrating behind the scenes, is there a reason that
watcher is not providing the list of resources that it is migrating?

Right now os-migrations is not yet going away, we're just not going to
add any more details to it. It will only be a set of pointers to
/servers/{server uuid}/migrations/{migration id} where all the details
will exist. The language on "deprecation" is a little odd, and "frozen"
is probably what it should be called.

Long term /os-migrations is actually one of those weird meta resources
which we'd ideally like to not have. There are a lot of these things
which really come down to "give me this arbitrary slice of servers that
are x, y, z". Which is really a search engine. And to be fast, has to be
optimized as a search engine (i.e. all attributes are indexed for fast
access). Which is a different than a database. Fortunately there is a
project that is working on that space -


Sean Dague

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