healthchecks can fail due to mod_wsgi lazy loading

[Oliver Walsh]

(forked from https://bugs.launchpad.net/tripleo/+bug/1843555/comments/20)

From mod_wsgi FAQ https://modwsgi.readthedocs.io/en/develop/user-guides/frequently-asked-questions.html:
Q: Why do requests against my application seem to take forever, but then after a bit they all run much quicker?
A: This is because mod_wsgi by default performs lazy loading of any application....

Where haproxy is not used this initial request is likely to be a healthcheck. The timeout on the healthcheck is 10s which *can* be exceeded.
Where haproxy is used the haproxy check requests appear to trigger lazy loading almost immediately after the container starts.