Release v1.39.0

[MrAlias]

Overview

Added

• Greatly reduce the cost of recording metrics in go.opentelemetry.io/otel/sdk/metric using hashing for map keys. (Use Set hash in Distinct (2nd attempt) #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. (trace,metric,log: add WithInstrumentationAttributeSet option #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. (feat(prometheus): Add observability for prometheus exporter #7345)
• Add experimental observability metrics in go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc. (feat: logs SDK observability - otlploggrpc exporter metrics #7353)
• Add temporality selector functions DeltaTemporalitySelector, CumulativeTemporalitySelector, LowMemoryTemporalitySelector to go.opentelemetry.io/otel/sdk/metric. (Add temporality selector functions #7434)
• Add experimental observability metrics for simple log processor in go.opentelemetry.io/otel/sdk/log. (Instrument the SimpleLogProcessor from sdk/log #7548)
• Add experimental observability metrics in go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc. (Instrument the otlptracegrpc exporter #7459)
• Add experimental observability metrics in go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp. (Instrument the otlptracehttp exporter #7486)
• Add experimental observability metrics for simple span processor in go.opentelemetry.io/otel/sdk/trace. (feat: sdk/trace: span processed metric for simple span processor #7374)
• Add experimental observability metrics in go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp. (Instrument the otlploghttp exporter #7512)
• Add experimental observability metrics for manual reader in go.opentelemetry.io/otel/sdk/metric. (Instrument manual reader from sdk/metric #7524)
• Add experimental observability metrics for periodic reader in go.opentelemetry.io/otel/sdk/metric. (feat: instrument periodic reader from 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. (otlploghttp: support OTEL_EXPORTER_OTLP_LOGS_INSECURE and OTEL_EXPORTER_OTLP_INSECURE env vars #7608)
• Add Enabled method to the Processor interface in go.opentelemetry.io/otel/sdk/log. All Processor implementations now include an Enabled method. (sdk/log: move Enabled method from FilterProcessor to Processor #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 for information on how to upgrade from go.opentelemetry.io/otel/semconv/v1.37.0.(Generate semconv/v1.38.0 #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. (Use Set hash in Distinct (2nd attempt) #7175)
• WithInstrumentationAttributes in go.opentelemetry.io/otel/trace synchronously de-duplicates the passed attributes instead of delegating it to the returned TracerOption. (trace,metric,log: change WithInstrumentationAttributes to not de-depuplicate the passed attributes in a closure #7266)
• WithInstrumentationAttributes in go.opentelemetry.io/otel/meter synchronously de-duplicates the passed attributes instead of delegating it to the returned MeterOption. (trace,metric,log: change WithInstrumentationAttributes to not de-depuplicate the passed attributes in a closure #7266)
• WithInstrumentationAttributes in go.opentelemetry.io/otel/log synchronously de-duplicates the passed attributes instead of delegating it to the returned LoggerOption. (trace,metric,log: change WithInstrumentationAttributes to not de-depuplicate the passed attributes in a closure #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. (Rename Self-Observability as just Observability #7302)
• Improve performance of histogram Record in go.opentelemetry.io/otel/sdk/metric when min and max are disabled using NoMinMax. (Don't track min and max when disabled #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 }. (feat: Improve error handling in prometheus exporter #7363)
• Replace fnv hash with xxhash in go.opentelemetry.io/otel/attribute for better performance. (Consider using xxHash instead of fnv64-1a #7371)
• The default TranslationStrategy in go.opentelemetry.io/exporters/prometheus is changed from otlptranslator.NoUTF8EscapingWithSuffixes to otlptranslator.UnderscoreEscapingWithSuffixes. (Prometheus exporter: change default translation strategy #7421)
• Improve performance of concurrent measurements in go.opentelemetry.io/otel/sdk/metric. (Use sync.Map and atomics to improve sum performance #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. (OTLP trace exporter include W3C trace flags (bits 0–7) in Span.Flags  #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. (Support custom error type semantics #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. (trace,metric,log: WithInstrumentationAttributes options to merge attributes #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. (Do not use the user-defined empty set when comparing sets. #7357)
• Return partial OTLP export errors to the caller in go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc. (Return partial OTLP export errors to the caller #7372)
• Return partial OTLP export errors to the caller in go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp. (Return partial OTLP export errors to the caller #7372)
• Return partial OTLP export errors to the caller in go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc. (Return partial OTLP export errors to the caller #7372)
• Return partial OTLP export errors to the caller in go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp. (Return partial OTLP export errors to the caller #7372)
• Return partial OTLP export errors to the caller in go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc. (Return partial OTLP export errors to the caller #7372)
• Return partial OTLP export errors to the caller in go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp. (Return partial OTLP export errors to the caller #7372)
• Fix AddAttributes, SetAttributes, SetBody on Record in go.opentelemetry.io/otel/sdk/log to not mutate input. (sdk/log: Fix AddAttributes, SetAttributes, SetBody on Record to not mutate input #7403)
• Do not double record measurements of RecordSet methods in go.opentelemetry.io/otel/semconv/v1.37.0. (Fix package documentation name and return err in semconv/v1.37.0 #7655)
• Do not double record measurements of RecordSet methods in go.opentelemetry.io/otel/semconv/v1.36.0. (Fix package documentation name and return error in semconv/v1.36.0 #7656)

Removed

• Drop support for [Go 1.23]. (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. (sdk/log: move Enabled method from FilterProcessor to Processor #7639)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.9%. Comparing base (12e421a) to head (3a9a5bc).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #7676     +/-   ##
=======================================
- Coverage   85.9%   85.9%   -0.1%     
=======================================
  Files        298     298             
  Lines      21741   21741             
=======================================
- Hits       18684   18680      -4     
- Misses      2645    2649      +4     
  Partials     412     412             

Files with missing lines	Coverage Δ
bridge/opencensus/version.go	100.0% <100.0%> (ø)
...xporters/otlp/otlpmetric/otlpmetricgrpc/version.go	100.0% <100.0%> (ø)
...xporters/otlp/otlpmetric/otlpmetrichttp/version.go	100.0% <100.0%> (ø)
exporters/otlp/otlptrace/version.go	100.0% <100.0%> (ø)
sdk/metric/version.go	100.0% <100.0%> (ø)
sdk/version.go	100.0% <100.0%> (ø)
version.go	100.0% <100.0%> (ø)

... and 2 files with indirect coverage changes

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[Copilot]

Pull request overview

This PR releases version 1.39.0 of the OpenTelemetry Go SDK along with corresponding experimental module versions (0.61.0 for metrics, 0.15.0 for logs, and 0.0.14 for schema). The release includes significant performance improvements, new experimental observability features, API enhancements, and bug fixes across the codebase.

Key Changes

• Version bumps across all modules from v1.38.0 to v1.39.0 for stable modules, and corresponding bumps for experimental modules
• Simplified version reference paths in versions.yaml from full paths to module-relative paths (e.g., ./internal/version.go)
• Updated CHANGELOG.md with comprehensive release notes for v1.39.0, including additions, changes, fixes, and removals

Reviewed changes

Copilot reviewed 38 out of 38 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
versions.yaml	Updated version numbers for all module-sets (stable-v1, experimental-metrics, experimental-logs, experimental-schema) and simplified version-refs paths to use module-relative paths
version.go	Bumped main version string from "1.38.0" to "1.39.0"
trace/internal/telemetry/test/go.mod	Updated trace module dependency to v1.39.0
trace/go.mod	Updated otel module dependency to v1.39.0
sdk/version.go	Bumped SDK version string from "1.38.0" to "1.39.0"
sdk/metric/version.go	Bumped metric SDK version string from "1.38.0" to "1.39.0"
sdk/metric/go.mod	Updated all otel module dependencies to v1.39.0
sdk/log/logtest/go.mod	Updated all otel module dependencies to v1.39.0
sdk/log/go.mod	Updated all otel module dependencies to v1.39.0
sdk/go.mod	Updated all otel module dependencies to v1.39.0
metric/go.mod	Updated all otel module dependencies to v1.39.0
log/logtest/go.mod	Updated all otel module dependencies to v1.39.0
log/go.mod	Updated all otel module dependencies to v1.39.0
go.mod	Updated metric and trace module dependencies to v1.39.0
exporters/zipkin/go.mod	Updated all otel module dependencies to v1.39.0
exporters/stdout/stdouttrace/internal/version.go	Updated version constant to "1.39.0"
exporters/stdout/stdouttrace/go.mod	Updated all otel module dependencies to v1.39.0
exporters/stdout/stdoutmetric/go.mod	Updated all otel module dependencies to v1.39.0
exporters/stdout/stdoutlog/go.mod	Updated all otel module dependencies to v1.39.0
exporters/prometheus/internal/version.go	Updated version constant to "0.61.0"
exporters/prometheus/go.mod	Updated all otel module dependencies to v1.39.0
exporters/otlp/otlptrace/version.go	Bumped version string from "1.38.0" to "1.39.0"
exporters/otlp/otlptrace/otlptracehttp/internal/version.go	Updated version constant to "1.39.0"
exporters/otlp/otlptrace/otlptracehttp/go.mod	Updated all otel module dependencies to v1.39.0
exporters/otlp/otlptrace/otlptracegrpc/internal/version.go	Updated version constant to "1.39.0"
exporters/otlp/otlptrace/otlptracegrpc/go.mod	Updated all otel module dependencies to v1.39.0
exporters/otlp/otlptrace/go.mod	Updated all otel module dependencies to v1.39.0
exporters/otlp/otlpmetric/otlpmetrichttp/version.go	Bumped version string from "1.38.0" to "1.39.0"
exporters/otlp/otlpmetric/otlpmetrichttp/go.mod	Updated all otel module dependencies to v1.39.0
exporters/otlp/otlpmetric/otlpmetricgrpc/version.go	Bumped version string from "1.38.0" to "1.39.0"
exporters/otlp/otlpmetric/otlpmetricgrpc/go.mod	Updated all otel module dependencies to v1.39.0
exporters/otlp/otlplog/otlploghttp/go.mod	Updated all otel module dependencies to v1.39.0
exporters/otlp/otlplog/otlploggrpc/go.mod	Updated all otel module dependencies to v1.39.0
bridge/opentracing/go.mod	Updated all otel module dependencies to v1.39.0
bridge/opencensus/version.go	Bumped version string from "1.38.0" to "1.39.0"
bridge/opencensus/test/go.mod	Updated all otel module dependencies to v1.39.0
bridge/opencensus/go.mod	Updated all otel module dependencies to v1.39.0
CHANGELOG.md	Added v1.39.0 release section with comprehensive notes covering additions, changes, fixes, and removals; reorganized previous unreleased content into the release section

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