Index Rollup job on index containing OpenTelemetry metrics

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):

OpenSearch & OpenSearch Dashboards v3.2

DataPrepper v2.12.1

OpenTelemetry metrics obtained by OtelCollector, sent to DataPrepper and ingested into OpenSearch using this pipeline in DataPrepper:

metric-pipeline:
source:
otel_metrics_source:
  ssl: false
  output_format: otel

processor:
 - otel_metrics:
 - copy_values:
    entries:
    - from_key: “time”
      to_key: “@timestamp”

sink:
- opensearch:
    hosts: [ “http://opensearch-node1:9200” ]
    insecure: true
    index_type: metric-analytics-plain
    bulk_size: 4

Describe the issue:
The created index in OpenSearch follows the OpenTelemetry definition, where metric documents have a field ‘name’ containing the metric name (e.g. “system.cpu.utilization”) and a field ‘value’ containg the metric value.

When creating a rollup up job in OpenSearch Dashboards I have not found a possibility to specify for which metrics aggregations shall be created. Let’s “system.cpu.utilization” shall be aggregated to Max, Min, Avg, and “system.memory.utilization” shall not be aggregated at all?
Is this the correct way for OpenTelemetry metrics to do aggregation via rollup?

Note
Actually I need only Avg. But there seems to be a problem according to [BUG] querying rollup on avg and value_count throws null_pointer_exception · Issue #1179 · opensearch-project/index-management · GitHub

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