Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3f1b9ed) 91.18% compared to head (719ff40) 91.18%.
Report is 13 commits behind head on main.

❗ Current head 719ff40 differs from pull request most recent head 6390294. Consider uploading reports for the commit 6390294 to get more accurate results

@@            Coverage Diff            @@
##               main    #6052   +/-   ##
=========================================
  Coverage     91.18%   91.18%           
- Complexity     5623     5627    +4     
=========================================
  Files           618      618           
  Lines         16580    16586    +6     
  Branches       1642     1644    +2     
=========================================
+ Hits          15118    15124    +6     
  Misses         1013     1013           
  Partials        449      449           

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This behavior is governed by the spec here and I would be surprised if it was changed to support this.

A couple of thoughts:

You could use a AutoConfigurationCustomizerProvider to customizer your OTLP exporters and add the headers programatically.

Someting like:

  @Override
  public void customize(AutoConfigurationCustomizer autoConfiguration) {
    autoConfiguration.addSpanExporterCustomizer(
            (spanExporter, configProperties) -> {
              if (spanExporter instanceof OtlpGrpcSpanExporter) {
                spanExporter.shutdown().join(10, TimeUnit.SECONDS);
                return ((OtlpGrpcSpanExporter) spanExporter).toBuilder().addHeader("foo", "value,value").build();
              }
              return spanExporter;
            });
  }

There's a general moratorium on enhancing the environment variable scheme. Instead, we want to mature the file configuration scheme. There is experimental java support for file configuration in otel java as described here. The config for this type of use might look like:

# Configure tracer provider.
tracer_provider:
  processors:
    - batch:
         exporter:
           otlp:
             endpoint: ..
             headers:
               key: "value,value"

Thanks for the reply! I'll look into your suggestion

Thanks for the help @jack-berg, this got me unblocked. If you don't mind, I think I may update the otel-java-instrumentation example impl with the CustomizerProvider you shared.