Graphite scaler is returning the earliest datapoint of a query, not the latest.

[bpinske]

Report

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Expected Behavior

Graphite's scaler acts on the most recent data available from a given query.

Actual Behavior

The scaler will act on the most outdated value returned by a query for a given time range.

Steps to Reproduce the Problem

1. Define a scaler definition with a QueryTime of 1 hour
2. Observe scaling behaviours act on hour-old data.

Logs from KEDA operator

example

KEDA Version

2.5.0

Kubernetes Version

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Platform

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Scaler Details

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Anything else?

Here you can see the graphite server response returns values in order of oldest to latest. With the final element of the response array being the most up-to-date timestamp. Graphite's scaler should be acting on the final element of the response array, not the first.

• https://graphite-api.readthedocs.io/en/latest/api.html#json
• https://github.com/kedacore/keda/blob/main/pkg/scalers/graphite_scaler.go#L197

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[zroubalik]

@bpinske do you think, that there might be some usecase where keeping the current behavior (oldest) makes sense?

[bpinske]

It seems very unlikely to me there is any legitimate use in allowing people to intentionally use out of date data.
Prometheus's scaler does not have any equivalent back-in-time functionality either.