Show multiple metric values in KeptnMetric

[rakshitgondwal]

Introduce a new range.storedResults field in the KeptnMetric struct. This field would be defined as the total number of results we want to store in the Status of the KeptnMetric.
The metrics-controller would query the SLI provider in an interval of fetchIntervalSeconds and keep the last spec.range.storedResults amount of results. It basically acts as an LRU with a capacity of spec.range.storedResults.
The maximum amount should be tested and found as part of this ticket - a good value could be 255.

Later, we can modify the status field to have a status.results field that would contain a slice/array of a Result struct.
The Result struct can have the value, rawValue, lastUpdated fields for a particular metric.

This whole thing might look somewhat like this:

apiVersion: metrics.keptn.sh/v1alpha3
kind: KeptnMetric
metadata:
  name: podtato-head
spec:
  provider:
    name: "my-provider"
  query: "sum(kube_pod_container_resource_limits{resource='cpu'})"
  fetchIntervalSeconds: 5
  range:
    interval: "5m"
    step: "1m"
    aggregation: "p90"
    storedResults: 5
status:
  results:
  - value: 1
    range:
    - interval: 5m
      step: 1m
      aggregaion: max
    lastUpdated: ...
  - value: 1
    rawValue: []byte
    range:
    - interval: 5m
      step: 1m
      aggregaion: max
    lastUpdated: ....
  errMsg: nil

Tasks

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1. Update the metrics API to support multiple metric values #2082
   +0
   
2. Modify the metrics controller to support multiple metric values #2083
   metrics-operator +1
   

[rakshitgondwal]

What did we decide to do with the rawValue over here? Should it be removed? Showing rawValue for every metric will make the CRD more lengthy.

cc @RealAnna @thisthat @bacherfl

[rakshitgondwal]

Also, should we have a slice or an array for results?

[prakrit55]

Hey @rakshitgondwal, is this still not done yet, I will work on it.

[rakshitgondwal]

Hey @prakrit55, the first part of this issue has been completed, and I am working on the second part right now.

[prakrit55]

It looked similar to an issue, so I approached. Thanks for the response.

[mowies]

What did we decide to do with the rawValue over here? Should it be removed? Showing rawValue for every metric will make the CRD more lengthy.

CC'ing again @RealAnna @thisthat @bacherfl

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be
closed if no further activity occurs. Thank you for your contributions.

[rakshitgondwal]

Have a PR under review that will close this issue.

[rakshitgondwal]

Closing as both the tasks have been completed.