Verify metric OTLP exporters compliance with metric specification

[MrAlias]

Specification: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.25.0/specification/metrics/sdk_exporters/otlp.md

Create issues for anything not compliant.

[MadVikingGod]

General

• Non Normative OTLP Metrics Exporter is a Push Metric Exporter which sends metrics via the OpenTelemetry Protocol.
• OTLP Metrics Exporter MUST support both Cumulative and Delta Aggregation Temporality.
• The exporter MUST provide configuration according to the OpenTelemetry Protocol Exporter specification. Note This is covered by Verify metric OTLP exporters compliance with the configuration specification #4512.
• If a language provides a mechanism to automatically configure a MetricReader to pair with the associated Exporter (e.g., using the OTEL_METRICS_EXPORTER environment variable), then by default:
  • The exporter MUST be paired with a periodic exporting MetricReader.
  • The exporter MUST configure the default aggregation temporality on the basis of instrument kind using the OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE variable as described below.
  • The exporter MUST configure the default aggregation on the basis of instrument kind using the OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION variable as described below if it is implemented.

Additional Configuration

• env vars:
  • OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE
    • Default cumulative
    • Allowed values:
      • Cumulative
      • Delta
      • LowMemory
  • OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION
    • Default explicit_bucket_histogram
    • Allowed values:
      • explicit_bucket_histogram
      • base2_exponential_bucket_histogram

[pellared]

https://github.com/open-telemetry/opentelemetry-go/tree/16643aea3063604eab37e435ac63e94dda413bbe is compliant with https://github.com/open-telemetry/opentelemetry-specification/blob/v1.26.0/specification/metrics/sdk_exporters/otlp.md.