Backend: Add functionality to export Kyverno Reporter Data Metrics to Prometheus

Description:

Add functionality in the backend to export Kyverno Policy Reporter data metrics to Prometheus for monitoring and visualization.

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Tasks:

1. Integration with Prometheus

   • Set up Prometheus metrics endpoint in the backend.
   • Define and register custom metrics for Kyverno policy violations (e.g., counters, gauges).

2. Data Processing

   • Fetch Kyverno Policy Reporter data using the existing client.
   • Parse and transform the data into Prometheus-compatible metrics.

3. Metrics Export

   • Push the transformed metrics to the Prometheus endpoint.
   • Ensure proper labeling (e.g., policy name, severity, namespace).

4. Error Handling and Logging

   • Handle errors during data fetching, transformation, and export.
   • Implement logging for debugging and monitoring.

5. Testing

   • Write unit tests for metric transformation and export logic.
   • Perform integration tests with Prometheus to validate metric ingestion.

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Acceptance Criteria:

• Kyverno data metrics (e.g., violations, compliance scores) are exported to Prometheus.
• Metrics include appropriate labels for detailed filtering and monitoring.
• Robust error handling and logging are implemented.
• Unit and integration tests validate the functionality.

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