Harvest should add forecasting with Prometheus's `predict_linear`

[cgrinds]

Links

• https://prometheus.io/docs/prometheus/latest/querying/functions/#predict_linear
• https://stackoverflow.com/questions/56606452/how-to-use-forcasting-in-prometheus-predict-linear
• https://www.dbi-services.com/blog/predict-the-future-with-prometheus/

[Hardikl]

customer discussion here: https://github.com/NetApp/harvest/discussions/2518

[rahulguptajss]

verified in main