prometheus-openstack-exporter: support TLS

This ps adds support for TLS.

Change-Id: I3270a7138d15075d032834d8df551870da8fadbe

prometheus-openstack-exporter/exporter/main.py

@@ -111,6 +111,7 @@ if __name__ == '__main__':
         'OS_USER_DOMAIN_NAME',
         os.getenv('OS_USER_DOMAIN_NAME'))
     os_region = config.get('OS_REGION_NAME', os.getenv('OS_REGION_NAME'))
+    os_cacert = config.get('OS_CACERT', os.getenv('OS_CACERT'))
     os_timeout = config.get(
         'TIMEOUT_SECONDS', int(
             os.getenv(
@@ -136,6 +137,7 @@ if __name__ == '__main__':
         os_username,
         os_user_domain,
         os_region,
+        os_cacert,
         os_timeout,
         os_retries)
     oscache = OSCache(os_polling_interval, os_region)

prometheus-openstack-exporter/exporter/osclient.py

@@ -38,6 +38,7 @@ class OSClient(object):
             username,
             user_domain,
             region,
+            verify,
             timeout,
             retries):
         self.keystone_url = keystone_url
@@ -51,6 +52,8 @@ class OSClient(object):
         self.token = None
         self.valid_until = None
         self.session = requests.Session()
+        if verify is not None:
+            self.session.verify = verify
         self.session.mount(
             'http://', requests.adapters.HTTPAdapter(max_retries=retries))
         self.session.mount(