[Openstack-operators] [openstack-dev] [openstack-operators] [glance] Austin summit summary: Rolling upgrades

Nikhil Komawar nik.komawar at gmail.com
Thu May 5 06:06:40 UTC 2016

Hello everyone,

Just wanted to send a brief summary of the discussions at the summit.
This list is not holistic however, it covers the relevant aspects that
various stakeholders need to be aware of.

  * The intent is that we want operators to be able to upgrade from one
    Glance release to the next with minimal (ideally, zero) downtime.

  * Nova's been working on this, so there's a good example of how to
    accomplish this. Also, the product working group has a cross-project
    spec on this topic.

  * Glance DB is the one component that would require some sophisticated
    logic to avoid the downtime. Other services are being handled by
    upgrade & swap mechanism.

  * Some discussion was around relative comparison on what other
    services are doing:In terms of performance there's simple schemain
    Glance thoughcan have massive data.

    The different approaches today include: 

    oslo versioned objects

    neutron: expansion/contraction scheme; expand, lazy updates, force
    contract after some time

    ironic: not using versioned objects, pinning the version

    cinder: split across multiple releases - add table, code can handle both

  * Besides these there was some discussion around best practices for
    upgrades: The preferred upgrade scheme is first DB, then registry
    and then API.

  * There were some research items: documenting the draining protocol
    for Glance nodes handling uploads. Write up alternatives in the spec
    based on findings what other projects are achieving; sign-ups
    include mclaren for cinder, rosmaita for neutron, nikhil for nova.
    More volunteers are welcome.

For more information please reach out to me on #openstack-glance, email,
reply here etc.



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