feat(metrics-exporters): configure temporality via env var

[pichlermarc]

Which problem is this PR solving?

Previously, the aggregation temporality could only be changed by explicitly setting it in the exporters constructor. This PR changes this by implementing the spec around the OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE variable.

Setting this variable will allow users to configure temporality preference. Invalid values will default to cumulative and will be logged as a warning.

Related to (but does not close) #3193

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• Existing unit tests
• Added unit tests

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

Merging #3305 (d044862) into main (30a81bd) will increase coverage by 0.37%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3305      +/-   ##
==========================================
+ Coverage   93.46%   93.84%   +0.37%     
==========================================
  Files         244      222      -22     
  Lines        7325     6526     -799     
  Branches     1515     1351     -164     
==========================================
- Hits         6846     6124     -722     
+ Misses        479      402      -77     

Impacted Files	Coverage Δ
...ckages/opentelemetry-core/src/utils/environment.ts	90.90% <ø> (ø)
...porter-metrics-otlp-grpc/src/OTLPMetricExporter.ts	100.00% <100.00%> (ø)
...er-metrics-otlp-http/src/OTLPMetricExporterBase.ts	63.41% <100.00%> (+18.58%)	⬆️
...-otlp-http/src/platform/node/OTLPMetricExporter.ts	100.00% <100.00%> (ø)
...orter-metrics-otlp-proto/src/OTLPMetricExporter.ts	100.00% <100.00%> (ø)
...s/opentelemetry-core/src/platform/node/sdk-info.ts	0.00% <0.00%> (-100.00%)	⬇️
...opentelemetry-core/src/platform/node/globalThis.ts	0.00% <0.00%> (-100.00%)	⬇️
...pentelemetry-core/src/platform/node/performance.ts	0.00% <0.00%> (-100.00%)	⬇️
...perimental/packages/otlp-exporter-base/src/util.ts	78.94% <0.00%> (-15.79%)	⬇️
...ckages/opentelemetry-exporter-zipkin/src/zipkin.ts	84.48% <0.00%> (-15.52%)	⬇️
... and 24 more

[svetlanabrennan]

Thanks for working on this. I think we should add some documentation in the readme around using these environment variables similar to this.

I know the spec mentions all these details but I think it's helpful for new otel users to see some quick documentation around these env variable options when using these exporters.

Maybe this documentation work can be done in a separate PR since I know we have an issue open to document latest metrics SDK.

[pichlermarc]

Thanks for working on this. I think we should add some documentation in the readme around using these environment variables similar to this.

I know the spec mentions all these details but I think it's helpful for new otel users to see some quick documentation around these env variable options when using these exporters.

Maybe this documentation work can be done in a separate PR since I know we have an issue open to document latest metrics SDK.

I added the env var to the docs and adapted the table for use in the metrics exporters. It bloats up the diff a bit but I think it fits within the scope of this PR. 🙂

However, I also found that several environment variables that were listed in the GRPC metrics exporter's readme are not respected. I have kept those in for now.

[pichlermarc]

Failing build will be fixed by #3328 🙂

[legendecas]

Thanks for working on this!

[legendecas]

@pichlermarc I can not update this PR's branch so please update it with the latest main branch and feel free to merge this PR! :D