[metricstransformprocessor] Support count aggregation type for aggregate_labels action

[lopes-felipe]

Component(s)

processor/metricstransform

Is your feature request related to a problem? Please describe.

I'd like to substitute aggregation by metricstransformprocessor for some of our recording rules. It's performing very well, however, it currently doesn't support counting aggregated metrics up by specified label_set, which is our blocker. It would be useful for users to support aggregation_type count in metricstransformprocessor.

Describe the solution you'd like

I haven't looked into the code base yet, but a simple implementation would be returning the number of data points (dps.Len()) at a specific time.

We could configure aggregation with the count type as:

    "metricstransform":
        "transforms":
        - "action": "insert"
          "include": "kube_pod_info"
          "match_type": "strict"
          "new_name": "cluster_namespace:pod:count"
          "operations":
          - "action": "aggregate_labels"
            "aggregation_type": "count"
            "label_set":
            - "namespace"

Describe alternatives you've considered

I don't have any other alternatives for now.

Additional context

This is purely a duplication of this issue, in order to draw attention to the proposed solution. Feel free to close this once we manage to move forward with the original one.

[github-actions]

Pinging code owners:

• processor/metricstransform: @dmitryax

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[lopes-felipe]

PR merged. Closing the issue.