Comment 1 for bug 1917645

There is two use case to support:
1) the notifications are used for something critical (e.g. billing based on usage) and therefore the failure to send notification should be also lead to the failure of some resource consumption (e.g. new VM creation)

2) the notifications are only used for non mission critical things, like monitoring / telemetry. So a failed notification sending should not lead to the failure of resource allocation.

The solution needs to support both cases so we need to make the error handling configurable. So let's make a new boolean config option [notifications]sending_failure_is_fatal . The default of this option needs to be True to keep the current behavior the default, so the exceptions are raised up in the stack and force the failure of the overall operation. If it is set to False then exceptions are caught and logged instead of propagated.

The solution needs to work for both versioned and unversioned notifications.