cdap-tca-hi-lo: a TCA application enhanced for Amsterdam/ONAP R1
This page is intended to give a broad overview of a microservice which has been onboarded with the DCAE platform and should be considered the "launch page" for others to find out basic information about your microservice. "Others" will include testers, DCAE/ASDC Service Designers, team members from other subsystems (Policy, CLAMP), etc.
Name:
cdap-tca-hi-lo
Synopsis/Description:
The cdap-tca-hi-lo app was first delivered as part of ONAP R0. In that release, it was intended to be an application that established a software architecture for building CDAP applications that demonstrate sufficient unit test coverage and reusable libraries for ingesting DMaaP MR feeds formatted according to the VES standard. Functionally, it performs a simple comparison of an incoming performance metric(s) against both a high and low threshold.
In the Amsterdam release, this microservice will be enhanced roadmap to meet the release requirements. The code will be used in the following ONAP use cases:
- Enhance TCA app to support R1 vCPE use case (requires new configuration model)
- also needs to support the ONAP R1vFW, vDNS/vLB use cases
- unchanged from R0 DCAE analytics perspective; primary difference is the deployment of the TCA app is via CLAMP and the new DCAE controller
Detailed Description:
This CDAP application is driven by the VES collector which outputs to Message Router. This Message Router topic is the source for the CDAP application which will read each incoming message. If a message meets the Common Event Format (CEF, v28.3) as specified by the VES 5.3 standard (AttServiceSpecification-VesEventListener-v5.3.docx, Rev: 5.3, 6/22/17), it will be parsed and if it contains a message which matches the policy configuration for a given metric (denoted primarily by the "eventName" (NEW, 8/25/17) and the "fieldPath"), the value of the metric will be compared to the "thresholdValue". If that comparison indicates that a Control Loop Event Message should be generated, the application will output the alarm to the Message Router Sink topic in a format that matches the interface spec defined in the ONAP Control Loop Operational Policy (see section titled "Control Loop Event Messages").
Assumptions:
TCA output will be similar to R0 implementation, where CL event will be triggered each time threshold rules are met.
- Support for ABATEMENT event is not strictly necessary in the vFW or vDNS/vLB use cases as the Policy team has an "ABATEMENT not expected" configuration setting. In the context of the vCPE use case, the CLEAR event (aka ABATED event) is driven by a measured metric (i.e. packet loss equal to 0) rather than by the lapse of a threshold crossing event over some minimum number of measured intervals. Thus, this requirement can be accommodated by use of the low threshold with a policy of "direction = 0". Hence, for this release, the cdap-tca-hi-lo implementation will keep only the minimal state needed to correlate an ABATED event with the corresponding ONSET event. This correlation will be indicated by the requestID in the Control Loop Event Message.
CDAP Programming Paradigm
The ONAP R0 version of this microservice was built using the flowlet paradigm. We have also successfully built it as a batch pipeline. For Amsterdam/ONAP R1, the code has been refactored to allow for delivery as either a flowlet or a batch pipeline. We expect that for this release the implementation will stay with the flowlet version since other parts of the DCAE platform do not yet support CDAP pipelines.
Public APIs:
MR Interface - Source
The source interface to TCA is Message Router; the input topic is expected to contain CEF messages (v28.3) as defined in the VES specification. Sample 1 and Sample 2 contain sample data based on the known schema in this spec as of 8/9/17. This data can be used as a guide for planning and development, but should not be considered authoritative for any of the use cases.
Sample 1 - Sample data for vFW and vDNS use cases; ves5.3-measurement-vf5vdns.txt ves5.3-measurement-vf5vdns.txt expand source?
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Table 2: Configurable Properties Exposed through the Policy Interface
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JSON Field
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JSON sub-field
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Description
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JSON Field | JSON sub-field | Description | Notes |
|---|---|---|---|
| { | |||
| domain | the domain datatype of the VES message | Must be measurementsForVfScaling | |
| metricsPerEventName | [ { | an array that describes parameters associating a closed loop flow to the policy governing this TCA instance | |
| eventName | a unique identifier that represents an event name that this TCA instance will act on | From VES 5.3 spec: "It should be understood that events are well structured packages of information, identified by an eventName, which are asynchronously communicated to subscribers who are interested in the eventName. Events can convey measurements, faults, syslogs, threshold crossing alerts and others types of information. Events are simply a way of communicating well-structured packages of information to one or more instances of an Event Listener service." | |
| controlLoopSchemaType | this is a field which will be used to derive the schema of the Control Loop Event Message | Valid values for the Amsterdam release: VM | VNF | |
| policyScope | the scope of this policy message | ||
| policyName | a name identifying this policy message | ||
| policyVersion | a version identifying this policy message | ||
| thresholds | an array of one or more thresholds that are managed as part of a given closed loop | ||
| closedLoopControlName | the name that specifies which control loop this TCA instance is a part of | ||
| version | the version of the control loop | ||
| fieldPath | a value used to derive the metric within VES message that this TCA will apply to | expected to be part of a measurementsForVfScaling domain event message | |
| thresholdValue | the value of the metric which will trigger this threshold | must be numeric | |
| direction | |||
| severity | an identifier specifying the precendence of this threshold evalution; thresholds will be evaluated from highest severity (CRITICAL) to lowest (NORMAL); a given VES message will only trigger one threshold | expected values: CRITICAL | MAJOR | MINOR | WARNING| NORMAL | |
| closedLoopEventStatus | an identifier used to describe whether this threshold should be associated with a control loop ONSET action or whether it would describe a condition that indicates such a condition has ended (i.e. the condition has ABATED). Note that ABATED alerts will be correlated to ONSET events based on the following key fields. | expected values: ONSET | ABATED |
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Contact | Role | Notes |
|---|---|---|
Contact | Role | Notes |
| ONAP TSC | Technical Steering Committee | This microservice was specifically developed for ONAP R0 and later enhanced for ONAP R1. Functionally, it has similarities to the cdap-mtca microservice used in 1707/1710 attECOMP however the code bases are different. |
Known Service Use Case(s):
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