Hi Elisha,
Thanks for your quick response. I think I got your points.
To double confirm, further questions are coming :):
1. Regardless if there is template definition, Vitrage constructs a graph
based on the data from plugins defined in datasources conf. Let's call it
"global graph". Is it right?
2. "entities" and "relationships" defined in template "definitions" won't
add any new vertex and edge to the "global graph". They are only used to be
referred by "condition"/"action" in "scenarios" section. "condition" also uses
them to construct another graph("ScenarioEvaluator._evaluate_and_condition"),
let's call it "template graph". This template graph is used to find
occurrences of a template graph in the "global"
graph("NXAlgorithm.sub_graph_matching").
3. If so, which graph will be applied by the actions by ScenarioEvaluator?
For example, will "AddCausalRelationship" add "causes" edge to the "global
graph" or "template graph"?
I suppose it should be "global graph". If so, it is possible the "global graph"
will grow very huge someday?
Thanks,
Tony
From: Rosensweig, Elisha (Nokia - IL)
Sent: Tuesday, April 19, 2016 7:00 PM
To: Wang, Tony T (Nokia - CN); Weyl, Alexey (Nokia - IL); Afek, Ifat (Nokia -
IL); Shamir, Ohad (Nokia - IL)
Subject: RE: [Vitrage] questions about "relationships"
Hi Tony,
Thanks for your interest in Vitrage! Any questions you might have, please send
us. You may also send them to the openstack mailing list, and we will answer
there as well.
Regarding your question:
* In the templates, the definitions in the "definitions" section are
used only by the scenario(s) within the template - the condition, as well as
the action, might reference these.
* These templates are used for business logic for the Scenario
Evaluator, to detect patterns in the Entity Graph and perform subsequent
actions.
* On the other hand, the populating of this Entity Graph is done via
Datasources. In the Transformer of each datasource, we define how we want to
integrate the data received into the Entity Graph, what labels each edge
(=relationship) will have etc.
For example, the InstanceTransformer will define that whenever we add an
instance to the Entity Graph, the instance is related to it's host with a
"contains" relationship. The template, on the other hand, states "IF there is a
host in error AND this host contains an instance, THEN do XXX".
So indeed, we need the conditions in the template to use the same "language" as
the transformers do, for example in using the labels. Currently, this mapping
is implicitly assumed to be identical (i.e., the two use the same labels). In
the future we will probably add a mapping configuration file, which maps the
transformer values to those in the templates.
Is this clear?
Thanks,
Elisha
From: Wang, Tony T (Nokia - CN)
Sent: Tuesday, April 19, 2016 1:13 PM
To: Wang, Tony T (Nokia - CN); Weyl, Alexey (Nokia - IL); Afek, Ifat (Nokia -
IL); Rosensweig, Elisha (Nokia - IL); Shamir, Ohad (Nokia - IL)
Subject: RE: [Vitrage] questions about "relationships"
Looks like "EvaluatorEventTransformer._create_neighbors" is used to create the
edge for relationship.
Is so, is it overlapped to define the relationship between "nova.instance" and
"nova.host" since "InstanceTransformer._create_host_neighbor" should do the
same work?
Thanks,
Tony
From: Wang, Tony T (Nokia - CN)
Sent: Tuesday, April 19, 2016 5:35 PM
To: '[email protected]'; '[email protected]';
'[email protected]'; '[email protected]'
Subject: [Vitrage] questions about "relationships"
All,
I found Vitrage is an very impressive OpenStack project! :)
I have a few questions about the example:
https://github.com/openstack/vitrage/blob/master/doc/source/vitrage-template-format.rst#example-1-basic-rca-and-deduced-alarmstate
In this example, there is a "relationships" definition between nova host and
nova instance:
- relationship:
source: host
target: instance
relationship_type: contains
template_id : host_contains_instance
My questions:
1. Is "relationship" used to create an edge or not?
2. I don't find the code for edge creation from "relationship". If not,
the edge between "nova.host" and "nova.instance" should be created by function
"InstanceTransformer._create_host_neighbor". Right?
3. If so, what's the purpose for "relationship"? Is it only used to parse
the "condition" part in "scenarios"?
Thanks in advance,
Tony
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