v1.15.0 release

Release of core packages

• opentelemetry-api
• opentelemetry-sdk

and exporter packages:

• opentelemetry-exporter-otlp (gRPC + HTTP/JSON)
• opentelemetry-exporter-prometheus

What's Changed

• Reapply "Change OTLP HTTP content_type default to binary (#2558)" by @ThomsonTan in https://github.com/open-telemetry/opentelemetry-cpp/pull/2564
• [DOC] Fix OTLP documentation: Default endpoint is wrong for OTLP/HTTP by @alanwest in https://github.com/open-telemetry/opentelemetry-cpp/pull/2560
• [BUILD] Fix old style cast warning by @keith in https://github.com/open-telemetry/opentelemetry-cpp/pull/2567
• [EXPORTER] Gzip compression support for OTLP/HTTP and OTLP/gRPC exporter by @perhapsmaple in https://github.com/open-telemetry/opentelemetry-cpp/pull/2530
• [BUILD] update vcpkg submodule to 2024.02.14 by @ThomsonTan in https://github.com/open-telemetry/opentelemetry-cpp/pull/2575
• [SDK] Support for OTEL_SERVICE_NAME by @willie in https://github.com/open-telemetry/opentelemetry-cpp/pull/2577
• [EXPORTER] Support URL-encoded values for OTEL_EXPORTER_OTLP_HEADERS by @pyohannes in https://github.com/open-telemetry/opentelemetry-cpp/pull/2579
• [BUILD] CMake cleanup for message() by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2582
• [BUILD] Bump CMake minimum required version to 3.9 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2581
• [BUILD] Provide LIKELY / UNLIKELY macros by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2580
• [EXPORTER] OTLP: Fix missing ResourceMetrics SchemaURL by @perhapsmaple in https://github.com/open-telemetry/opentelemetry-cpp/pull/2587
• [etw] cleanup include path by @ThomsonTan in https://github.com/open-telemetry/opentelemetry-cpp/pull/2594
• Upgrade to googletest 1.14.0 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2596
• Upgrade to nlohmann_json 3.11.3 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2595
• [bazel] Move -std=c++14 to .bazelrc by @keith in https://github.com/open-telemetry/opentelemetry-cpp/pull/2600
• [bazel] Fix -std=c++14 warning on Windows by @keith in https://github.com/open-telemetry/opentelemetry-cpp/pull/2601
• Upgrade to benchmark 1.8.3 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2597
• Upgrade to prometheus 1.2.4 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2598
• [doc] Fix typo: Asynchronouse -> Asynchronous in meter.h by @yijiem in https://github.com/open-telemetry/opentelemetry-cpp/pull/2604
• [BUILD] Do not link prometheus-cpp::util when it doesn't exist by @owent in https://github.com/open-telemetry/opentelemetry-cpp/pull/2606
• [SDK] Remove unused variable by @keith in https://github.com/open-telemetry/opentelemetry-cpp/pull/2609
• [METRICS SDK] Remove extra OfferMeasurement call in SyncMetricsStorage::OfferMeasurement by @ThomsonTan in https://github.com/open-telemetry/opentelemetry-cpp/pull/2610
• [MISC] Use set -e on all shell scripts and pass shellcheck --severity=error by @johnbley in https://github.com/open-telemetry/opentelemetry-cpp/pull/2616
• [CI] Add shellcheck --severity=error as a CI step by @johnbley in https://github.com/open-telemetry/opentelemetry-cpp/pull/2618
• [CI] Upgrade to abseil 20240116.1 (CMake only) by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2599
• [CI] Benchmark, provide units with --benchmark_min_time by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2621
• [EXPORTER] OTLP file exporter by @owent in https://github.com/open-telemetry/opentelemetry-cpp/pull/2540
• [CI] Use platform CMake by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2627
• [PROTO] Upgrade to opentelemetry-proto 1.2.0 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2631
• [SDK] DefaultLogHandler to print errors to std::cerr, add LogLevel::None by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2622
• [SEMANTIC CONVENTIONS] Upgrade to semantic convention 1.25.0 by @esigo in https://github.com/open-telemetry/opentelemetry-cpp/pull/2633
• [DOC] Add readme and examples for OTLP FILE exporters. by @owent in https://github.com/open-telemetry/opentelemetry-cpp/pull/2638
• [SEMANTIC CONVENTIONS] Rework on semantic conventions 1.25.0 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2640
• [DOC] Update INSTALL.md by @chenhong805 in https://github.com/open-telemetry/opentelemetry-cpp/pull/2592
• [RELEASE] Release opentelemetry-cpp version 1.15.0 by @marcalff in https://github.com/open-telemetry/opentelemetry-cpp/pull/2639

Important changes:

• [EXPORTER] Gzip compression support for OTLP/HTTP and OTLP/gRPC exporter #2530
  • In the OtlpHttpExporterOptions and OtlpGrpcExporterOptions, a new field called compression has been introduced. This field can be set to "gzip” to enable gzip compression.
  • The CMake option WITH_OTLP_HTTP_COMPRESSION is introduced to enable gzip compression support for the OTLP HTTP Exporter and includes a dependency on zlib.
• [SDK] Change OTLP HTTP content_type default to binary #2558
• [CI] Use platform CMake #2627
  • The CI in github no longer install a different version of cmake.
  • It now always use the cmake provided by the platform.
  • As part of this change, the script ci/setup_cmake.sh was renamed to ci/setup_googletest.sh, for clarity, now that this script only installs googletest.
• [SDK] DefaultLogHandler to print to std::cerr, add LogLevel::None #2622
  • Change DefaultLogHandler output
    • Before, the default internal logger, DefaultLogHandler, used to print to std::cout.
    • Now, DefaultLogHandler prints errors and warnings to std::cerr, as expected, while printing info and debug messages to std::cout.
    • Applications that expected to find the opentelemetry-cpp internal error log in std::cout may need adjustments, either by looking at std::cerr instead, or by using a custom log handler.
  • Additional LogLevel::None
    • LogLevel::None is a new supported log level, which does not print any message.
    • Custom log handlers may need to implement a new case, to avoid compiler warnings.
    • Numbering of log levels like OTEL_INTERNAL_LOG_LEVEL_ERROR has changed, which requires to rebuild, as the SDK ABI differs.

New Contributors

• @alanwest made their first contribution in https://github.com/open-telemetry/opentelemetry-cpp/pull/2560
• @keith made their first contribution in https://github.com/open-telemetry/opentelemetry-cpp/pull/2567
• @willie made their first contribution in https://github.com/open-telemetry/opentelemetry-cpp/pull/2577
• @yijiem made their first contribution in https://github.com/open-telemetry/opentelemetry-cpp/pull/2604
• @johnbley made their first contribution in https://github.com/open-telemetry/opentelemetry-cpp/pull/2616
• @chenhong805 made their first contribution in https://github.com/open-telemetry/opentelemetry-cpp/pull/2592

Full Changelog: https://github.com/open-telemetry/opentelemetry-cpp/compare/v1.14.2...v1.15.0