Keystone With HTTPd in Devstack

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Keystone has been slowly pushing away from being deployed with Eventlet and the keystone-all script in favour of the more traditional httpd mod_wsgi application method. There has been discussion of Eventlet’s place in OpenStack before and its (mis)use has led to numerous subtle bugs and problems, however from my opinion in Keystone the most important reasons to move away from Eventlet are:

  • Eventlet does not support Kerberos authentication.
  • pyOpenSSL only releases the GIL around some SSL verification commands. This leads to a series of hacks to prevent long running crypto commands blocking Eventlet threads and thus the entire Keystone process.
  • There are already a lot of httpd authentication/authorization plugins that we could make use of in Keystone.
  • It’s faster to have things handled by httpd modules in C than in Python.

Keystone has shipped with sample WSGI scripts and httpd configuration files since Foslom and documentation for how to use them is available however most guides and service wrappers (upstart, systemd etc) will use the keystone-all method.

To get some wider adoption and understanding of the process I’ve just added Keystone with httpd support into devstack. Simply set:


in your localrc or environment variables and re-run ./stack.sh to try it out.

P.S. Swift can also be deployed this way by adding swift to the (comma separated) services list.