Greetings. I've been working on some scalability enhancements to Turnstile[1], and I believe it's about time to announce that work here. I'm hoping that people here find it useful, not to mention help with the final debugging :)
Turnstile is a distributed rate-limiting middleware, which replaces Nova's built-in RateLimitingMiddleware with a version that can apply rate limiting across multiple nova-api nodes. (Turnstile itself is actually more general, and can be used for rate limiting with any WSGI application.) It uses an external Redis server for storing data about requests. To use Turnstile with Nova requires the nova_limits[2] package (another such package exists for using Turnstile with Keystone; I'm hoping the developer of that package will chime in with the appropriate link, since I've forgotten it…). My recent work has focused on enhancing Turnstile's scalability; in particular, I've been working on sharding the ephemeral request data across multiple Redis servers. To do that, it will be necessary to use a Redis proxy called Nutcracker[3]. Turnstile is not 100% compatible with Nutcracker, but fortunately the incompatible bits can be worked around easily, and so NutJob[4] was created. The final piece of the scalability work I have is Subway[5], which allows the rate limit configuration to be mirrored across multiple Redis servers. (Why not use Redis's master/slave? Well, Subway also forwards the messages that are used to notify Turnstile of when the limits configuration needs to be reloaded.) Here's hoping ya'll find these projects useful! [1] https://github.com/klmitch/turnstile [2] https://github.com/klmitch/nova_limits [3] Also known as twemproxy; https://github.com/twitter/twemproxy [4] Yeah, I know, bad pun; https://github.com/klmitch/nutjob [5] Because it carries rate limit configuration from Turnstile to Turnstile: https://github.com/klmitch/subway -- Kevin L. Mitchell <[email protected]> _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : [email protected] Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
