Record instance actions and events

Record when an action is initiated on an instance, and the underlying
events related to completing that action.

Actions will typically occur at the API level and should match what a
user intended to do with an instance.  Events will typically track what
happens behind the scenes and may include things that would be unclear
for a user if exposed, but should be beneficial to an admin/deployer.

Adds a new wrapper to the compute manager.  The wrapper will record when
an event begins and finishes from the point of view of the compute
manager.  It will also record errors if they occur.

Blueprint instance-actions

Change-Id: I801f3e796d091e146413f84c2ccfab95ad2e1af4

1 files changed, 5 insertions, 1 deletions

diff --git a/nova/db/sqlalchemy/models.py b/nova/db/sqlalchemy/models.py
index fd8348678..e91988a95 100644
--- a/nova/db/sqlalchemy/models.py
+++ b/nova/db/sqlalchemy/models.py
@@ -1005,7 +1005,11 @@ class InstanceFault(BASE, NovaBase):
 
 
 class InstanceAction(BASE, NovaBase):
-    """Track client actions on an instance."""
+    """Track client actions on an instance.
+
+    The intention is that there will only be one of these per user request.  A
+    lookup by (instance_uuid, request_id) should always return a single result.
+    """
     __tablename__ = 'instance_actions'
     id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
     action = Column(String(255))