On 02/26/2014 08:25 AM, Dolph Mathews wrote:

On Tue, Feb 25, 2014 at 2:38 PM, Jay Pipes <jaypi...@gmail.com <mailto:jaypi...@gmail.com>> wrote:

    On Tue, 2014-02-25 at 11:47 -0800, Morgan Fainberg wrote:
    > For purposes of supporting multiple backends for Identity (multiple
    > LDAP, mix of LDAP and SQL, federation, etc) Keystone is planning to
    > increase the maximum size of the USER_ID field from an upper
    limit of
    > 64 to an upper limit of 255. This change would not impact any
    > currently assigned USER_IDs (they would remain in the old simple
    UUID
    > format), however, new USER_IDs would be increased to include the IDP
    > identifier (e.g. USER_ID@@IDP_IDENTIFIER).

    -1

    I think a better solution would be to have a simple translation table
    only in Keystone that would store this longer identifier (for folks
    using federation and/or LDAP) along with the Keystone user UUID
    that is
    used in foreign key relations and other mapping tables through
    Keystone
    and other projects.


Morgan and I talked this suggestion through last night and agreed it's probably the best approach, and has the benefit of zero impact on other services, which is something we're obviously trying to avoid. I imagine it could be as simple as a user_id to domain_id lookup table. All we really care about is "given a globally unique user ID, which identity backend is the user from?"

On the downside, it would likely become bloated with unused ephemeral user IDs, so we'll need enough metadata about the mapping to implement a purging behavior down the line.
UUIDs are 32 chars long. Its really just uuid@@uuid that pushes us over the 64 character limit. If we can shorten up the IDP_ID we can fit everything in 64 chars (which means only Nova needs to expand its column size)

What if we enumerated IDPs by index, from 10000000 to 99999999 or something comparable, and then use the new domain_index (or prot domain id to not be a uuid). Then the above scheme would work and no migration would be required.



    The only identifiers that would ever be communicated to any
    non-Keystone
    OpenStack endpoint would be the UUID user and tenant IDs.

    > There is the obvious concern that projects are utilizing (and
    storing)
    > the user_id in a field that cannot accommodate the increased upper
    > limit. Before this change is merged in, it is important for the
    > Keystone team to understand if there are any places that would be
    > overflowed by the increased size.

    I would go so far as to say the user_id and tenant_id fields should be
    *reduced* in size to a fixed 16-char BINARY or 32-char CHAR field for
    performance reasons. Lengthening commonly-used and frequently-joined
    identifier fields is not a good option, IMO.

    Best,
    -jay

    > The review that would implement this change in size
    > is https://review.openstack.org/#/c/74214 and is actively being
    worked
    > on/reviewed.
    >
    >
    > I have already spoken with the Nova team, and a single instance has
    > been identified that would require a migration (that will have a fix
    > proposed for the I3 timeline).
    >
    >
    > If there are any other known locations that would have issues
    with an
    > increased USER_ID size, or any concerns with this change to USER_ID
    > format, please respond so that the issues/concerns can be addressed.
    >  Again, the plan is not to change current USER_IDs but that new ones
    > could be up to 255 characters in length.
    >
    >
    > Cheers,
    > Morgan Fainberg
    > ---
    > Morgan Fainberg
    > Principal Software Engineer
    > Core Developer, Keystone
    > m...@metacloud.com <mailto:m...@metacloud.com>
    >
    >
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