OTLP trace exporter include W3C trace flags (bits 0–7) in Span.Flags #7438

nikhilmantri0902 · 2025-10-01T11:34:25Z

Span.Flags should include:
Bits 0–7: span’s W3C TraceFlags (e.g., sampled)
Bits 8–9: “has parent isRemote” and “parent isRemote” per OTLP spec

Update the trace exporter to include the span’s W3C trace flags in the lower 8 bits and keep the existing 8–9 isRemote logic.
Conceptually:
For spans: flags := uint32(sd.SpanContext().TraceFlags() & 0xff)
Always set SPAN_FLAGS_CONTEXT_HAS_IS_REMOTE_MASK
If sd.Parent().IsRemote(), also set SPAN_FLAGS_CONTEXT_IS_REMOTE_MASK
Assign s.Flags = flags
Apply the same for links using the link’s SpanContext.TraceFlags() for bits 0–7 and the link’s SpanContext.IsRemote() for bits 8–9.

codecov · 2025-10-01T11:36:14Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.1%. Comparing base (07a26be) to head (d504a2c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #7438   +/-   ##
=====================================
  Coverage   86.1%   86.1%           
=====================================
  Files        291     291           
  Lines      25613   25615    +2     
=====================================
+ Hits       22056   22059    +3     
+ Misses      3184    3183    -1     
  Partials     373     373

Files with missing lines	Coverage Δ
...ers/otlp/otlptrace/internal/tracetransform/span.go	`93.2% <100.0%> (+<0.1%)`	⬆️

... and 1 file with indirect coverage changes

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CHANGELOG.md

nikhilmantri0902 · 2025-10-05T08:31:43Z

@dmathieu can we merge this? Resolving conflicts.

dmathieu · 2025-10-05T08:38:27Z

We require 2 approvals.

nikhilmantri0902 · 2025-10-06T05:00:11Z

@flc1125 can you take a look please?

flc1125 · 2025-10-09T11:11:33Z

@flc1125 can you take a look please?

Sorry, I was on vacation recently. Just got back and have been quite busy lately. I need some time.

exporters/otlp/otlptrace/internal/tracetransform/span.go

## Overview ### Added - Greatly reduce the cost of recording metrics in `go.opentelemetry.io/otel/sdk/metric` using hashing for map keys. (#7175) - Add `WithInstrumentationAttributeSet` option to `go.opentelemetry.io/otel/log`, `go.opentelemetry.io/otel/metric`, and `go.opentelemetry.io/otel/trace` packages. This provides a concurrent-safe and performant alternative to `WithInstrumentationAttributes` by accepting a pre-constructed `attribute.Set`. (#7287) - Add experimental observability for the Prometheus exporter in `go.opentelemetry.io/otel/exporters/prometheus`. Check the `go.opentelemetry.io/otel/exporters/prometheus/internal/x` package documentation for more information. (#7345) - Add experimental observability metrics in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc`. (#7353) - Add temporality selector functions `DeltaTemporalitySelector`, `CumulativeTemporalitySelector`, `LowMemoryTemporalitySelector` to `go.opentelemetry.io/otel/sdk/metric`. (#7434) - Add experimental observability metrics for simple log processor in `go.opentelemetry.io/otel/sdk/log`. (#7548) - Add experimental observability metrics in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc`. (#7459) - Add experimental observability metrics in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp`. (#7486) - Add experimental observability metrics for simple span processor in `go.opentelemetry.io/otel/sdk/trace`. (#7374) - Add experimental observability metrics in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp`. (#7512) - Add experimental observability metrics for manual reader in `go.opentelemetry.io/otel/sdk/metric`. (#7524) - Add experimental observability metrics for periodic reader in `go.opentelemetry.io/otel/sdk/metric`. (#7571) - Support `OTEL_EXPORTER_OTLP_LOGS_INSECURE` and `OTEL_EXPORTER_OTLP_INSECURE` environmental variables in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp`. (#7608) - Add `Enabled` method to the `Processor` interface in `go.opentelemetry.io/otel/sdk/log`. All `Processor` implementations now include an `Enabled` method. (#7639) - The `go.opentelemetry.io/otel/semconv/v1.38.0` package. The package contains semantic conventions from the `v1.38.0` version of the OpenTelemetry Semantic Conventions. See the [migration documentation](./semconv/v1.38.0/MIGRATION.md) for information on how to upgrade from `go.opentelemetry.io/otel/semconv/v1.37.0.`(#7648) ### Changed - `Distinct` in `go.opentelemetry.io/otel/attribute` is no longer guaranteed to uniquely identify an attribute set. Collisions between `Distinct` values for different Sets are possible with extremely high cardinality (billions of series per instrument), but are highly unlikely. (#7175) - `WithInstrumentationAttributes` in `go.opentelemetry.io/otel/trace` synchronously de-duplicates the passed attributes instead of delegating it to the returned `TracerOption`. (#7266) - `WithInstrumentationAttributes` in `go.opentelemetry.io/otel/meter` synchronously de-duplicates the passed attributes instead of delegating it to the returned `MeterOption`. (#7266) - `WithInstrumentationAttributes` in `go.opentelemetry.io/otel/log` synchronously de-duplicates the passed attributes instead of delegating it to the returned `LoggerOption`. (#7266) - Rename the `OTEL_GO_X_SELF_OBSERVABILITY` environment variable to `OTEL_GO_X_OBSERVABILITY` in `go.opentelemetry.io/otel/sdk/trace`, `go.opentelemetry.io/otel/sdk/log`, and `go.opentelemetry.io/otel/exporters/stdout/stdouttrace`. (#7302) - Improve performance of histogram `Record` in `go.opentelemetry.io/otel/sdk/metric` when min and max are disabled using `NoMinMax`. (#7306) - Improve error handling for dropped data during translation by using `prometheus.NewInvalidMetric` in `go.opentelemetry.io/otel/exporters/prometheus`. ⚠️ **Breaking Change:** Previously, these cases were only logged and scrapes succeeded. Now, when translation would drop data (e.g., invalid label/value), the exporter emits a `NewInvalidMetric`, and Prometheus scrapes **fail with HTTP 500** by default. To preserve the prior behavior (scrapes succeed while errors are logged), configure your Prometheus HTTP handler with: `promhttp.HandlerOpts{ ErrorHandling: promhttp.ContinueOnError }`. (#7363) - Replace fnv hash with xxhash in `go.opentelemetry.io/otel/attribute` for better performance. (#7371) - The default `TranslationStrategy` in `go.opentelemetry.io/exporters/prometheus` is changed from `otlptranslator.NoUTF8EscapingWithSuffixes` to `otlptranslator.UnderscoreEscapingWithSuffixes`. (#7421) - Improve performance of concurrent measurements in `go.opentelemetry.io/otel/sdk/metric`. (#7427) - Include W3C TraceFlags (bits 0–7) in the OTLP `Span.Flags` field in `go.opentelemetry.io/exporters/otlp/otlptrace/otlptracehttp` and `go.opentelemetry.io/exporters/otlp/otlptrace/otlptracegrpc`. (#7438) - The `ErrorType` function in `go.opentelemetry.io/otel/semconv/v1.37.0` now handles custom error types. If an error implements an `ErrorType() string` method, the return value of that method will be used as the error type. (#7442) ### Fixed - Fix `WithInstrumentationAttributes` options in `go.opentelemetry.io/otel/trace`, `go.opentelemetry.io/otel/metric`, and `go.opentelemetry.io/otel/log` to properly merge attributes when passed multiple times instead of replacing them. Attributes with duplicate keys will use the last value passed. (#7300) - The equality of `attribute.Set` when using the `Equal` method is not affected by the user overriding the empty set pointed to by `attribute.EmptySet` in `go.opentelemetry.io/otel/attribute`. (#7357) - Return partial OTLP export errors to the caller in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc`. (#7372) - Return partial OTLP export errors to the caller in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp`. (#7372) - Return partial OTLP export errors to the caller in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc`. (#7372) - Return partial OTLP export errors to the caller in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp`. (#7372) - Return partial OTLP export errors to the caller in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc`. (#7372) - Return partial OTLP export errors to the caller in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp`. (#7372) - Fix `AddAttributes`, `SetAttributes`, `SetBody` on `Record` in `go.opentelemetry.io/otel/sdk/log` to not mutate input. (#7403) - Do not double record measurements of `RecordSet` methods in `go.opentelemetry.io/otel/semconv/v1.37.0`. (#7655) - Do not double record measurements of `RecordSet` methods in `go.opentelemetry.io/otel/semconv/v1.36.0`. (#7656) ### Removed - Drop support for [Go 1.23]. (#7274) - Remove the `FilterProcessor` interface in `go.opentelemetry.io/otel/sdk/log`. The `Enabled` method has been added to the `Processor` interface instead. All `Processor` implementations must now implement the `Enabled` method. Custom processors that do not filter records can implement `Enabled` to return `true`. (#7639)

chore: added implementation and test cases

e5bd32d

nikhilmantri0902 requested review from MrAlias, XSAM, dashpole, dmathieu, flc1125 and pellared as code owners October 1, 2025 11:34

nikhilmantri0902 added 3 commits October 1, 2025 17:13

chore: added changelog entry

e0ad319

chore: update changelog entry

fd586b0

fix: failing lint

8b7f1c9

dmathieu reviewed Oct 2, 2025

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chore: modify changelog

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dmathieu approved these changes Oct 2, 2025

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chore: merged main and resolved changelog conflicts

74ea39b

flc1125 reviewed Oct 10, 2025

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exporters/otlp/otlptrace/internal/tracetransform/span.go Outdated Show resolved Hide resolved

nikhilmantri0902 added 2 commits October 11, 2025 14:27

chore: cleanup buildSpanFlagsWith

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Merge branch 'main' into feat/trace_flags_bits_07_export

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flc1125 approved these changes Oct 11, 2025

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Merge branch 'main' into feat/trace_flags_bits_07_export

d504a2c

dmathieu merged commit fa8e48b into open-telemetry:main Oct 13, 2025
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MrAlias added this to the v1.39.0 milestone Oct 14, 2025

MrAlias mentioned this pull request Dec 5, 2025

Release v1.39.0 #7676

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OTLP trace exporter include W3C trace flags (bits 0–7) in Span.Flags #7438

OTLP trace exporter include W3C trace flags (bits 0–7) in Span.Flags #7438

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OTLP trace exporter include W3C trace flags (bits 0–7) in Span.Flags #7438

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