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Introduction
This page provides a brief overview on the process involved in onboarding new MS onto DCAE GEN2 controller platform and integration with SDC, Policy and CLAMP for modelling, design and service instantiation. A more comprehensive documentation will be follow and delivered part of documentation project.
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The DCAE Controller includes following components. The platform components will be deployed via platform level blueprint (not handled through onboarding steps noted here).
- Cloudify Manager
- Consul
- DeploymentHander
- Policy-Handler
- ServiceChangeHandler
- Inventory-API
- Postgres
- Registrator
- ConfigBinding Service
- CDAP Broker
For component/MS to be deployed into DCAE platform would go through below phases
- Onboarding Phase
- Design Phase
- Runtime
Onboarding
During this phase, each of the component owner should create a meta data describing the components. There are two main artifacts required to be defined
Data-Formats
Data formats are descriptions of data---they are the data contract between your component and other components. You need to describe the available outputs and assumed inputs of your components as data formats. These data descriptions are onboarded into SDC
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Component-spec
The component specification is a JSON that is used to describe and configure your component. The component specification contains the following top-level groups of information:
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The developers will upload the spec (data-formats, component spec) developed into catalog using dcae_cli/tosca tool. Once validated, spec’s will be published into SDC catalog so they can be used for service creation.
Design Phase
Design comprises of two steps.
Template creation
The TOSCA models generated from onboarding is used here to do this composition. Using SDC designer tool – individual reusable templates are created and stored in catalog.
Service Composition
Once the designer template is created, they can be used for Service composition (in SDC/CLAMP) to generate a Cloudify blueprint.
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Once approved, SDC sends notification via an event onto a message router topic for DCAE-ServiceChangeHandler, which queries SDC to retrieve the blueprint and store into DCAE inventory.
Runtime
Instantiation flow is triggered by update from ASDC/CLAMP where the DCAE controller deploys the components associated with service which is identified in the cloudify blueprint.
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The complete flow with DCAE platform is depicted below.
Code snippet to fetch configuration from Configbinding service
For Docker containers, the configuration identified part of MS component-spec is retrieved from Configbinding service during application start-up and when notified by controller on a configuration change. The docker container part of init script - should query configbindingservice and fetch the configuration.
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The data is represented as key-value pair gets written into a file within container above. The MS should parse the configuration and apply within MS as required.
DMAAP binding
The dmaap topic stream are identified in compenent_spec as "subscribe" and "publish" streams. Each topic should be identified by the component developer using unique config_key. When the configuration gets pushed into the container by controller, the topic configuration is pushed under below structure.
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The config_key defined will map the value specified in the component_spec. For an anonymous (non-secure) topic, the username/password field will be defaulted to null.
Sample configuration from DCAE Controller
Below is sample Configuration for VESCollector retrieved from DCAE platform (configbinding service).
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