Merge branch 'feature_10945_Service_KPI_of_VNF_using_exporter_endpoint' into 'master'

- Fill in the form, adding at least the member vnf index:

![VM Migration](assets/500px-VM_Migration.png)

## How to deploy a VNF that comes with a Prometheus exporter

The Service KPI (Key Performance Indicator) feature in OSM enables efficient monitoring and assurance of network service performance. With the introduction of the Exporter Endpoint, users can now collect Service KPIs directly from VNFs that come with a Prometheus Exporter.

### Usage of Service KPI feature

Service KPIs are metrics used to measure the performance of a VNF (Virtualized Network Function) service. These metrics can help operators to ensure that the VNF service is meeting the required service level agreements (SLAs) and to identify any issues that may be impacting service quality.

VNF Package is onboarded with Prometheus job template, and this template is stored in the mongo dB OSM will add the Prometheus job for collection of service KPI metrics. Prometheus will start collecting the service KPI metrics for the VNF using the provided exporter endpoint. 

By monitoring and analyzing these Service KPI metrics, network operators can gain insight into the performance of VNFs and take proactive steps to optimize service delivery and ensure that quality of service is as per expectation. 

Reference diagram:

![Service KPI of VNF using Exporter Endpoint Reference Diagram](assets/700px_service_kpi_vnf.png)

### How to change the VNF package to include the VNF exporter endpoints

- Ensure that the VNF package includes the necessary components for exporting metrics, including the exporter endpoints along with Prometheus job template.

```yaml

vnfd:

  df:

    exporters-endpoints:

      metric-path: /metrics

      metric-port: 9100

      external-connection-point-ref: vnf-cp0-ext

```

### How to check that the VNF exporter endpoints are exposing their metrics

- Instantiate the NS (Network Service) within the OSM environment using the onboarded VNF package.

- Confirm that the Service KPI metrics are flowing seamlessly from the VNF instances to OSM-Prometheus, whose graphical interface can be visited at the URL <http://$IP:9091/>.