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So, one thing to remember, I don't think etcd has an authz mechanism yet.

You usually want your fernet keys to be accessible by just the keystone nodes and no others.

This might require a etcd cluster just for keystone fernet tokens, which might work great. but is an operator overhead to install/maintain.

________________________________
From: Lance Bragstad [lbragstad at gmail.com]
Sent: Thursday, June 08, 2017 10:34 AM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [all] etcd3 as base service - update

After digging into etcd a bit, one place this might be help deployer experience would be the handling of fernet keys for token encryption in keystone. Currently, all keys used to encrypt and decrypt tokens are kept on disk for each keystone node in the deployment. While simple, it requires operators to perform rotation on a single node and then push, or sync, the new key set to the rest of the nodes. This must be done in lock step in order to prevent early token invalidation and inconsistent token responses.

An alternative would be to keep the keys in etcd and make the fernet bits pluggable so that it's possible to read keys from disk or etcd (pending configuration). The advantage would be that operators could initiate key rotations from any keystone node in the deployment (or using etcd directly) and not have to worry about distributing the new key set. Since etcd associates metadata to the key-value pairs, we might be able to simplify the rotation strategy as well.

On Thu, Jun 8, 2017 at 11:37 AM, Mike Bayer <mbayer at redhat.com<mailto:mbayer at redhat.com>> wrote:


On 06/08/2017 12:47 AM, Joshua Harlow wrote:
So just out of curiosity, but do people really even know what etcd is good for? I am thinking that there should be some guidance from folks in the community as to where etcd should be used and where it shouldn't (otherwise we just all end up in a mess).

So far I've seen a proposal of etcd3 as a replacement for memcached in keystone, and a new dogpile connector was added to oslo.cache to handle referring to etcd3 as a cache backend.  This is a really simplistic / minimal kind of use case for a key-store.

But, keeping in mind I don't know anything about etcd3 other than "it's another key-store", it's the only database used by Kubernetes as a whole, which suggests it's doing a better job than Redis in terms of "durable".   So I wouldn't be surprised if new / existing openstack applications express some gravitational pull towards using it as their own datastore as well.    I'll be trying to hang onto the etcd3 track as much as possible so that if/when that happens I still have a job :).





Perhaps a good idea to actually give examples of how it should be used, how it shouldn't be used, what it offers, what it doesn't... Or at least provide links for people to read up on this.

Thoughts?

Davanum Srinivas wrote:
One clarification: Since https://pypi.python.org/pypi/etcd3gw just
uses the HTTP API (/v3alpha) it will work under both eventlet and
non-eventlet environments.

Thanks,
Dims


On Wed, Jun 7, 2017 at 6:47 AM, Davanum Srinivas<davanum at gmail.com<mailto:davanum at gmail.com>>  wrote:
Team,

Here's the update to the base services resolution from the TC:
https://governance.openstack.org/tc/reference/base-services.html

First request is to Distros, Packagers, Deployers, anyone who
installs/configures OpenStack:
Please make sure you have latest etcd 3.x available in your
environment for Services to use, Fedora already does, we need help in
making sure all distros and architectures are covered.

Any project who want to use etcd v3 API via grpc, please use:
https://pypi.python.org/pypi/etcd3 (works only for non-eventlet services)

Those that depend on eventlet, please use the etcd3 v3alpha HTTP API using:
https://pypi.python.org/pypi/etcd3gw

If you use tooz, there are 2 driver choices for you:
https://github.com/openstack/tooz/blob/master/setup.cfg#L29
https://github.com/openstack/tooz/blob/master/setup.cfg#L30

If you use oslo.cache, there is a driver for you:
https://github.com/openstack/oslo.cache/blob/master/setup.cfg#L33

Devstack installs etcd3 by default and points cinder to it:
http://git.openstack.org/cgit/openstack-dev/devstack/tree/lib/etcd3
http://git.openstack.org/cgit/openstack-dev/devstack/tree/lib/cinder#n356

Review in progress for keystone to use etcd3 for caching:
https://review.openstack.org/#/c/469621/

Doug is working on proposal(s) for oslo.config to store some
configuration in etcd3:
https://review.openstack.org/#/c/454897/

So, feel free to turn on / test with etcd3 and report issues.

Thanks,
Dims

--
Davanum Srinivas :: https://twitter.com/dims




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