Delta Temporality Metrics with the C++ SDK / Collector

[Michaelh12304-work]

Is there a way to produce Metrics with the Delta Temporality using the C++ SDK / Collector??

I see this env var for example: OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE which does not seem to be present in the C++ SDK source code.

Some APM providers, in fact a number do not like the non delta kinds of metrics.

We are trying to use the doubleUpDownCounter and the Counter -- which is the one that does not work with Dynatrace.

Thanks

[lalitb]

@Michaelh12304-work You can set the preferred temporality as part of OTLP grpc/http exporter options -

opentelemetry-cpp/exporters/otlp/include/opentelemetry/exporters/otlp/otlp_grpc_metric_exporter_options.h

Line 31 in 19f0dc7

PreferredAggregationTemporality aggregation_temporality;

So something like this should work (rough code to give an idea):

OtlpGrpcMetricExporterOptions  options;
options.aggregation_temporality = PreferredAggregationTemporality::kDelta // or kCumulative or kLowMemory
OtlpGrpcMetricExporter exporter(options);

where (as per the specs),

• Cumulative: Choose cumulative aggregation temporality for all instrument kinds.
• Delta: Choose Delta aggregation temporality for Counter, Asynchronous Counter and Histogram instrument kinds, choose
  Cumulative aggregation for UpDownCounter and Asynchronous UpDownCounter instrument kinds.
• LowMemory: This configuration uses Delta aggregation temporality for Synchronous Counter and Histogram and uses Cumulative aggregation temporality for Synchronous UpDownCounter, Asynchronous Counter, and Asynchronous UpDownCounter instrument kinds.