Add warning log if auth_strategy is not keystone

A user came to the IRC channel with CLI errors:
"Client-side error: Validation failure: Missing project ID in
request where one is required."

The root cause was the [api_settings] auth_strategy was set to
"noauth" instead of "keystone".

This patch adds a warning log message to the API process that
warns users that typically the auth_strategy should be set to
keystone.
It also points the user to have an administrator check the keystone
settings in the octavia.conf.

Change-Id: I7793d7a9113b23ac88e7c53d5dc292a70b9453b5

octavia/api/v2/controllers/load_balancer.py

@@ -324,7 +324,9 @@ class LoadBalancersController(base.BaseController):
 
         if not load_balancer.project_id:
             raise exceptions.ValidationException(detail=_(
-                "Missing project ID in request where one is required."))
+                "Missing project ID in request where one is required. "
+                "An administrator should check the keystone settings "
+                "in the Octavia configuration."))
 
         self._auth_validate_action(context, load_balancer.project_id,
                                    constants.RBAC_POST)

octavia/cmd/api.py

@@ -20,6 +20,7 @@ from oslo_log import log as logging
 from oslo_reports import guru_meditation_report as gmr
 
 from octavia.api import app as api_app
+from octavia.common import constants
 from octavia import version
 
 
@@ -35,6 +36,11 @@ def main():
     port = cfg.CONF.api_settings.bind_port
     LOG.info("Starting API server on %(host)s:%(port)s",
              {"host": host, "port": port})
+    if cfg.CONF.api_settings.auth_strategy != constants.KEYSTONE:
+        LOG.warning('Octavia configuration [api_settings] auth_strategy is '
+                    'not set to "keystone". This is not a normal '
+                    'configuration and you may get "Missing project ID" '
+                    'errors from API calls."')
     srv = simple_server.make_server(host, port, app)
 
     srv.serve_forever()