While we don't have HTTP healthcheck in OpenStack [1], let's use
TCP-connection level to validate a service is up and running.
The reason is when "option httpchk" is specified, a complete HTTP request is
sent once the TCP connection is established, and responses 2xx and 3xx
are considered valid.
So given that, OpenStack APIs are responding with 401 or 500, this healthcheck
appears to be self-defeating [2].
Also introduce a new parameter to allow flexible timeout: api_timeout
(beside galera_timeout).
Sources:
[1] http://specs.openstack.org/openstack/oslo-specs/specs/kilo/oslo-middleware-healthcheck.html
[2] http://cbonte.github.io/haproxy-dconv/configuration-1.5.html#4-option%20httpchk
Change-Id: I0121d28daafa2f509162880e9934eb3e08ae4543
a8e71e7b33