The Event Switchboard

The way that CloudForms/ManageIQ handles events has changed with ManageIQ Capablanca. Prior to Capablanca events entered Automation at /System/Process/Event, and were redirected to the appropriate Instance under the /System/Event Class based on the translation of the #event_type variable:

For example #event_type might translate to request_created:

The Event Stream

For Capablanca (CloudForms Management Engine 5.5) event handling is expanded, and events are now handled as part of an event stream. The /System/Process/Event Class contains a new rel5 Relationship that redirects the handling of the event into the Event Switchboard:

/System/Event/${/#event_stream.event_namespace}/${/#event_stream.source}/${/#event_type}

Switchboard Components Parts

The Relationship into the Switchboard is broken down into three parts, each selected from the substitution of a run-time variable.

Event Stream Namespace

The ${/#event_stream.event_namespace} part of the Relationship translates to one of three Event Stream Namespaces: EmsEvent if the event's origin was from an External Management System (i.e. a Provider); MiqEvent if the event's origin was an internal CloudForms/ManageIQ-initiated Policy event; or RequestEvent if the event is related to an Automation Request (e.g. request_created):

Event Stream Source

Within each of the Event Stream Namespaces, are Classes that define the Event Stream Source Instances. The selection of source Class is made from the substitution of the ${/#event_stream.source} part of the /System/Process/Event rel5 Relationship. We can see that for the EmsEvent Namespace, these represent the various External Management Systems (Amazon, OpenStack, etc.):

Event Type

Under the apprpriate Event Stream Source Classes are Instances that define the processing required for each Event Type. The selection of Event Type is made from the substitution of the ${/#event_type} part of the /System/Process/Event rel5 Relationship. We can see that these represent the various events that the EventCatcher::Runner workers detect from the Provider message bus, for example for the Amazon Namespace:

The Event Type Instances contain one or more Relationships to Event Handlers in the /System/event_handlers Namespace that define what actions to take for that event. For example the Amazon event AWS_EC2_Instance_running will call the event_action_policy handler to push a new vm_start policy event through the Switchboard. It also calls the event_action_refresh handler to trigger a Provider refresh so that the current Instance details can be retrieved:

Event Handlers

The Event Handlers are Instances and Methods that perform the actual granular processing for each event. The Methods are builtin for execution efficiency; their code is not visible in the Automate Explorer.