Release v1.6.0/v0.28.0

[MrAlias]

⚠️ Notice ⚠️

This update is a breaking change of the unstable Metrics API.
Code instrumented with the go.opentelemetry.io/otel/metric will need to be modified.

Added

• Add metrics exponential histogram support.
  New mapping functions have been made available in sdk/metric/aggregator/exponential/mapping for other OpenTelemetry projects to take dependencies on. (Exponential Histogram mapping functions for public use #2502)
• Add Go 1.18 to our compatibility tests. (Add Go 1.18 to our supported versions. #2679)
• Allow configuring the Sampler with the OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG environment variables. (Support the OTEL_TRACES_SAMPLER* environment variables #2305, Allow setting the Sampler via environment variables #2517)
• Add the metric/global for obtaining and setting the global MeterProvider. (Adds metrics Global #2660)

Changed

• The metrics API has been significantly changed to match the revised OpenTelemetry specification.
  High-level changes include:

  • Synchronous and asynchronous instruments are now handled by independent InstrumentProviders.
    These InstrumentProviders are manged a Meter.
  • Synchronous and asynchronous instruments are grouped into their own packages based on value types.
  • Asynchronous callbacks can now be registered with a Meter.

  Be sure to check out the metric module documentation for more information on how to use the revised API. ([API EPIC 4/4] Fix tests and examples #2587, Adds metrics Global #2660)

Fixed

• Fallback to general attribute limits when span specific ones are not set in the environment. (Support OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT and OTEL_ATTRIBUTE_COUNT_LIMIT #2675, Support general attribute limits for spans #2677)

[codecov]

Codecov Report

Merging #2718 (a603ccc) into main (3dac50a) will decrease coverage by 0.0%.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main   #2718     +/-   ##
=======================================
- Coverage   76.7%   76.7%   -0.1%     
=======================================
  Files        181     181             
  Lines      12175   12175             
=======================================
- Hits        9349    9343      -6     
- Misses      2601    2607      +6     
  Partials     225     225             

Impacted Files	Coverage Δ
version.go	100.0% <100.0%> (ø)
sdk/trace/batch_span_processor.go	80.2% <0.0%> (-1.9%)	⬇️
exporters/jaeger/jaeger.go	90.3% <0.0%> (-0.9%)	⬇️