Templates Not Operator Support - Version 2¶
Overview¶
The Templates language supports the “or” and “and” operators at the moment. Many scenarios can’t be described by using only those two operators and thus we would like to add support for “not” operator as well.
Template Structure¶
The template is written in YAML language, with the following structure.
metadata:
version: <template version>
name: <unique template identifier>
description: <what this template does>
definitions:
entities:
- entity: ...
- entity: ...
relationships:
- relationship: ...
- relationship: ...
scenarios:
- scenario:
condition: <if statement true do the action>
actions:
- action: ...
All the sections are in use as described in the “vitrage-template-format.rst” file. But in the condition section it will be possible to write the “not” operator in addition to the “and” and “or” operators. The “not” operator can be used only before a relationship expression.
Condition Format¶
The condition which needs to be met will be phrased using the entities and relationships previously defined. The condition details are described in the “vitrage-template-format.rst” and the addition here is the new logical operator “not”:
“not” - indicates that the expression must not be satisfied in order for the condition to be met.
The following are examples of valid expressions, where X, Y and Z are relationships:
X
X and Y
X and Y and Z
X and not Y
X and not (Y or Z)
X and not X
Supported Use Cases¶
Use Case 1:¶
There exists an instance on Host but there is no Alarm on the instance.
+--------+ +--------+ Not +---------+ | Host | ------> | Vm | < - - - - | Alarm | +--------+ +--------+ +---------+metadata: version: 2 name: no_alarm_on_instance_that_contained_in_host description: when host contains vm that has no alarm on it, show implications on the host definitions: entities: - entity: category: ALARM name: instance_mem_performance_problem template_id: instance_alarm # some string - entity: category: RESOURCE type: nova.host template_id: host - entity: category: RESOURCE type: nova.instance template_id: instance relationships: - relationship: source: instance_alarm target: instance relationship_type: on template_id : alarm_on_instance - relationship: source: host target: instance relationship_type: contains template_id : host_contains_instance scenarios: - scenario: condition: host_contains_instance and not alarm_on_instance actions: - action: action_type: set_state properties: state: available action_target: target: host
Use Case 2:¶
There exists a host with no alarm.
+--------+ Not +---------+ | Host | < - - - - | Alarm | +--------+ +---------+metadata: version: 2 name: no_alarm_on_host description: when there is no alarm on the host, show implications on the host definitions: entities: - entity: category: ALARM name: host_high_mem_load template_id: host_alarm # some string - entity: category: RESOURCE type: nova.host template_id: host - entity: category: RESOURCE type: nova.instance template_id: instance relationships: - relationship: source: host_alarm # source and target from entities section target: host relationship_type: on template_id : alarm_on_host scenarios: - scenario: condition: not alarm_on_host actions: - action: action_type: set_state properties: state: available action_target: target: instance
Use Case 3:¶
The Switch is attached to a Host that contains a Vm. The Switch is also comprised to a Network which has a Port. There is no edge between the Vm and the Port.
+---------+ +---------+
+----------- | Host | --------> | Vm |
| +---------+ +---------+
| |
v |
+----------+ | N
| Switch | | o
+----------+ | t
| |
| |
| v
| +---------+ +---------+
+----------> | Network | <-------- | Port |
+---------+ +---------+
::
metadata:
version: 2
name: no_connection_between_vm_and_port
description: when there is no edge between the port and the vm, show implications on the instances
definitions:
entities:
- entity:
category: RESOURCE
type: nova.host
template_id: host
- entity:
category: RESOURCE
type: nova.instance
template_id: instance
- entity:
category: RESOURCE
type: switch
template_id: switch
- entity:
category: RESOURCE
type: neutron.network
template_id: network
- entity:
category: RESOURCE
type: neutron.port
template_id: port
relationships:
- relationship:
source: host
target: instance
relationship_type: contains
template_id : host_contains_instance
- relationship:
source: switch
target: host
relationship_type: connected
template_id : host_connected_switch
- relationship:
source: switch
target: network
relationship_type: has
template_id : switch_has_network
- relationship:
source: port
target: network
relationship_type: attached
template_id : port_attached_network
- relationship:
source: instance
target: port
relationship_type: connected
template_id : vm_connected_port
scenarios:
- scenario:
condition: host_contains_instance and host_connected_switch and switch_has_network and port_attached_network and not vm_connected_port
actions:
- action:
action_type: raise_alarm
properties:
alarm_name: instance_mem_performance_problem
severity: warning
action_target:
target: instance
Unsupported Use Cases¶
Use Case 1:¶
There is a Host contains Vm, which has no edge (“connection”) to a stack that has an alarm on it. Difference: The difference here from the graphs above, is that here there are two connected component subgraphs (the first is host contains vm, the second is alarm on stack), and the current mechanism doesn’t support such a use case of not operator between many connected component subgraphs. In the subgraphs above, we had only one vertex which was not connected to the main connected component subgraph.
+---------+ +---------+ Not +---------+ +---------+ | Host | --------> | Vm | - - - - - -> | Stack | <--------- | Alarm | +---------+ +---------+ +---------+ +---------+metadata: version: 2 name: host_contains_vm_with_no_edge_to_stack_that_has_alarm_on_it description: when host contains vm without and edge to a stack that has no alarms, show implications on the instances definitions: entities: - entity: category: RESOURCE type: nova.host template_id: host - entity: category: RESOURCE type: nova.instance template_id: instance - entity: category: RESOURCE type: heat.stack template_id: stack - entity: category: ALARM name: stack_high_mem_load template_id: stack_alarm relationships: - relationship: source: host target: instance relationship_type: contains template_id : host_contains_instance - relationship: source: stack_alarm target: stack relationship_type: on template_id : alarm_on_stack - relationship: source: instance target: stack relationship_type: attached template_id : instance_attached_stack scenarios: - scenario: condition: host_contains_instance and alarm_on_stack and not instance_attached_stack actions: - action: action_type: set_state properties: state: available action_target: target: instance
