[openstack-dev] [Mistral][Zaqar] Triggering Mistral workflows from Zaqar messages

Thomas Herve therve at redhat.com
Thu May 19 08:20:24 UTC 2016

On Wed, May 18, 2016 at 8:49 PM, Zane Bitter <zbitter at redhat.com> wrote:
> I've been lobbying the Mistral developers for $SUBJECT since, basically,
> forever.[1][2][3] I like to think after a couple of years I succeeded in
> changing their view on it from "crazy" to merely "unrealistic".[4] In the
> last few months I've had a couple of realisations though:
> 1) The 'pull' model I've been suggesting is the wrong one, architecturally
> speaking. It's asking Mistral to do too much to poll Zaqar queues.
> 2) A 'push' model is the correct architecture and it already exists in the
> form of Zaqar's Notifications, which suddenly makes this goal look very
> realistic indeed.
> I've posted a Zaqar spec for this here:
> https://review.openstack.org/#/c/318202/

Commented. I certainly need some more time to think about it.

> Not being super familiar with either project myself, I think this needs
> close scrutiny from Mistral developers as well as Zaqar developers to make
> sure I haven't got any of the details wrong. I'd also welcome any volunteers
> interested in implementing this :)
> One more long-term thing that I did *not* mention in the spec: there are
> both Zaqar notifications and Mistral actions for sending email and hitting
> webhooks. These are two of the hardest things for a cloud operator to
> secure. It would be highly advantageous if there were only _one_ place in
> OpenStack where these were implemented. Either project would potentially
> work - Zaqar notifications could call a simple, operator defined workflow
> behind the scenes for email/webhook notifications; alternatively the Mistral
> email/webhook actions could drop a message on a Zaqar queue connected to a
> notification - although the former sounds easier to me. (And of course
> clouds with only one of the services available could fall back to the
> current plugins.) Something to think about for the future...

And you're forgetting about Aodh alarm notifications, which are
webhooks as well. Unfortunately, I think none of them do a
particularly great job in terms of robustness and security. I
suggested moving away from doing webhook in Zaqar to Flavio in the
past, and I think he responded that he thought it was part of the core
functionality. It's hard to delegate such operations and create a
dependency on another project. Maybe we can start by creating some
library code.


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