Take WSGIScriptAlias into account in docker healthcheck.

Some services running as vhost, as nova_placement make
use of an  alias in which the wsgi service is mapped.
Currently, the nova_placement healthcheck has hardcoded
the alias in the curl [0] request, but if this alias
changes or other service modifies its from / to another,
then the check will start failing again.

[0] - https://github.com/openstack/tripleo-common/blob/master/healthcheck/nova-placement#L6

Change-Id: I5a325be424740e80eafd6b4abd8eb4b3111740aa
Closes-Bug: #1781623
(cherry picked from commit f1a1c324fb)

healthcheck/common.sh

@@ -50,9 +50,13 @@ get_url_from_vhost () {
   server_name=$(awk '/ServerName/ {print $2}' $vhost_file)
   ssl_enabled=$(awk '/SSLEngine/ {print $2}' $vhost_file)
   bind_port=$(grep -h "<VirtualHost .*>" $vhost_file | sed 's/<VirtualHost .*:\(.*\)>/\1/')
+  wsgi_alias=$(awk '/WSGIScriptAlias/ {print $2}' $vhost_file)
   proto=http
   if [[ $ssl_enabled == "on" ]]; then
     proto=https
   fi
-  echo ${proto}://${server_name}:${bind_port}/
+  if [[ $wsgi_alias != "/" ]]; then
+    wsgi_alias="${wsgi_alias}/"
+  fi
+  echo ${proto}://${server_name}:${bind_port}${wsgi_alias}
 }