We are happy to announce the 0.14.0 release.

[!WARNING] While most changes are source-compatible, there are a few breaking changes across multiple modules. Please review carefully before upgrading.

Key changes

1. Sealed interfaces

We have sealed many of the core interfaces. There are two sides of this decision:

• Cons: This makes it harder for third-party libraries to extend otel4s directly.
• Pros: It gives us much more flexibility to evolve the public API safely over time.

This change is especially important as we look ahead to the 1.0 release. The OpenTelemetry specification is still actively evolving, and sealing interfaces allows us to add new methods without breaking binary compatibility.

We know this is a trade-off. If feedback shows this experiment is not working well, we may unseal some interfaces in the future.

See the reasoning behind this change: https://github.com/typelevel/otel4s/issues/1029.

2. Attributes.Make

We have introduced the Attributes.Make typeclass to make it easier to turn your own domain values into Attributes.

For example:

case class User(id: Long, group: String)

implicit val userAttributesMake: Attributes.Make[User] =
  user => Attributes(Attribute("user.id", user.id), Attribute("user.group", user.group))

// now you can directly create attributes from your User
val attributes: Attributes = Attributes.from(User(1L, "admin"))

// use it naturally in spans:
Tracer[IO].span("find-user", Attributes.from(user))

This is especially useful when you want to consistently record attributes for domain entities such as users, orders, sessions, or request metadata.

3. mapK renamed to liftTo

As preparation for https://github.com/typelevel/otel4s/issues/1001, all mapK methods have been renamed to liftTo.

The change is binary-compatible. Old usages still compile, but you will see a deprecation warning pointing you to the new liftTo method.

This should make migrations smooth.

4. New Logging module

We now provide an experimental logging module:

• Spec: https://opentelemetry.io/docs/specs/otel/logs/
• Modules: otel4s-logs, otel4s-oteljava-logs, otel4s-sdk-logs, otel4s-sdk-exporter-logs

[!NOTE] The logging module is only for bridging logs from other logging frameworks into OpenTelemetry. It is not a replacement for a full logging API.

Examples:

• A library such as scribe or log4cats can use the otel4s-logs API to export logs over the OpenTelemetry protocol.
• OpenTelemetry-Java bindings are provided in otel4s-oteljava-logs.
• For Scala.js and Scala Native, otel4s-sdk-logs offers a pure Scala implementation.

This closes an important gap in the ecosystem, allowing structured logs to be exported alongside metrics and traces.

Check out the documentation for more details.

5. New AWS EKS resource detector

The detector provides EKS-specific resource attributes when running on AWS EKS. Check out the documentation for more details.

Kudos to @brbrown25.

6. New otel4s-oteljava-context-storage-testkit module

The opentelemetry-sdk-testing uses SettableContextStorage as a context storage, which is not compatible with the IOLocalContextStorage.

To address this, you can use the IOLocalTestContextStorage in your tests:

import cats.effect.IO
import org.typelevel.otel4s.oteljava.context.LocalContextProvider
import org.typelevel.otel4s.oteljava.testkit.context.IOLocalTestContextStorage

implicit val localContextProvider: LocalContextProvider[IO] = IOLocalTestContextStorage.localProvider[IO]

Check out the documentation for more details.

Kudos to @AlixBa.

7. New fromInMemory builder for *Testkit objects

In some cases, a program can rely on both Java instrumentation and Scala instrumentation. To make it easier to test such programs, we have added a fromInMemory method to all *Testkit objects.

Check out the documentation for more details.

Kudos to @AlixBa.

Acknowledgements

Big thanks to @NthPortal for thorough reviews and valuable feedback during this cycle. 🙌

What's Changed

Core

• logs: add core-logs module by @iRevive in https://github.com/typelevel/otel4s/pull/1013
• core-common: add AnyValue by @iRevive in https://github.com/typelevel/otel4s/pull/1009
• core-logs: add Severity by @iRevive in https://github.com/typelevel/otel4s/pull/1015
• Define hashCode as lazy val by @c0d33ngr in https://github.com/typelevel/otel4s/pull/1019
• core-common: add Attributes.Make by @iRevive in https://github.com/typelevel/otel4s/pull/1023
• core-logs: add LogRecordBuilder by @iRevive in https://github.com/typelevel/otel4s/pull/1018
• docs: update scaladoc example by @iRevive in https://github.com/typelevel/otel4s/pull/1034
• core-logs: add LoggerProvider, LoggerBuilder, and Logger by @iRevive in https://github.com/typelevel/otel4s/pull/1030
• Rename most mapK methods to liftTo by @NthPortal in https://github.com/typelevel/otel4s/pull/1002
• Seal public traits by @iRevive in https://github.com/typelevel/otel4s/pull/1037
• sdk-exporter-logs: add LogsProtoEncoder by @iRevive in https://github.com/typelevel/otel4s/pull/1057
• Add otel4s-oteljava-logs module by @iRevive in https://github.com/typelevel/otel4s/pull/1038
• Wire all logs modules together by @iRevive in https://github.com/typelevel/otel4s/pull/1077
• core-logs: add Logger.Meta by @iRevive in https://github.com/typelevel/otel4s/pull/1084
• Refactor InstrumentMeta by @iRevive in https://github.com/typelevel/otel4s/pull/1085

SDK

• sdk-logs: add LogRecordData by @iRevive in https://github.com/typelevel/otel4s/pull/1040
• Update opentelemetry-semconv to 1.37.0 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1051
• sdk-logs: add LogRecordLimits by @iRevive in https://github.com/typelevel/otel4s/pull/1041
• sdk-logs: add LogRecordLimitsAutoConfigure by @iRevive in https://github.com/typelevel/otel4s/pull/1058
• sdk-logs: add LogRecordExporter by @iRevive in https://github.com/typelevel/otel4s/pull/1056
• sdk-logs: add ConsoleLogRecordExporter by @iRevive in https://github.com/typelevel/otel4s/pull/1061
• sdk-logs: add LogRecordProcessor by @iRevive in https://github.com/typelevel/otel4s/pull/1055
• sdk-logs: Evaluate multiple processors sequentially by @iRevive in https://github.com/typelevel/otel4s/pull/1068
• sdk-logs: Add SimpleLogRecordProcessor by @iRevive in https://github.com/typelevel/otel4s/pull/1067
• sdk-logs: Add BatchLogRecordProcessor by @iRevive in https://github.com/typelevel/otel4s/pull/1066
• sdk-logs: Add SdkLogRecordBuilder by @iRevive in https://github.com/typelevel/otel4s/pull/1069
• sdk-logs: Add LogRecordExportersAutoConfigure by @iRevive in https://github.com/typelevel/otel4s/pull/1071
• sdk-logs: Add SdkLoggerProvider, SdkLoggerBuilder, and SdkLogger by @iRevive in https://github.com/typelevel/otel4s/pull/1072
• sdk-logs-testkit: Add LogsTestkit by @iRevive in https://github.com/typelevel/otel4s/pull/1070
• sdk-logs: add BatchLogRecordProcessorAutoConfigure by @iRevive in https://github.com/typelevel/otel4s/pull/1073
• sdk-logs: add LoggerProviderAutoConfigurer by @iRevive in https://github.com/typelevel/otel4s/pull/1075
• sdk-logs: add SdkLogs by @iRevive in https://github.com/typelevel/otel4s/pull/1076
• Add otel4s-sdk-logs module by @iRevive in https://github.com/typelevel/otel4s/pull/1039

SDK exporter

• sdk-exporter: update OTLP exporter docs by @iRevive in https://github.com/typelevel/otel4s/pull/1042
• sdk-exporter-logs: add OtlpLogRecordExporter by @iRevive in https://github.com/typelevel/otel4s/pull/1063
• Metrics SDK: Ignore empty and annotations unit by @lenguyenthanh in https://github.com/typelevel/otel4s/pull/1089

SDK Contrib AWS

• feat(AwsEksDetector): Adding in functionality for the AWSEksDetector similar to the java implementation. #783. by @brbrown25 in https://github.com/typelevel/otel4s/pull/1096
• chore(DockerHelper): switching to Concurrent instead of Async. #783. by @brbrown25 in https://github.com/typelevel/otel4s/pull/1098

Semantic Conventions

• semconv: fix semconv generation by @iRevive in https://github.com/typelevel/otel4s/pull/1047

OtelJava

• oteljava: add TracesTestkit#resetSpans by @iRevive in https://github.com/typelevel/otel4s/pull/1028
• oteljava-logs-test: add LogsTestkit by @iRevive in https://github.com/typelevel/otel4s/pull/1064
• unwrap IOLocalContextStorage from SettableContextStorageProvider in t… by @AlixBa in https://github.com/typelevel/otel4s/pull/996
• add fromInMemory on Testkits by @AlixBa in https://github.com/typelevel/otel4s/pull/1081

Build

• build: do not upload JS and SN artifacts by @iRevive in https://github.com/typelevel/otel4s/pull/1093
• sdk-exporter: try to address flaky tests by @iRevive in https://github.com/typelevel/otel4s/pull/1114

Documentation

• docs: add sttp and tapir to the ecosystem by @iRevive in https://github.com/typelevel/otel4s/pull/1024
• Use Resource.fromAutoCloseable in docs by @mzuehlke in https://github.com/typelevel/otel4s/pull/1033
• docs: add otel4s Java Agent example by @iRevive in https://github.com/typelevel/otel4s/pull/1044
• docs: add logs module configuration details by @iRevive in https://github.com/typelevel/otel4s/pull/1074
• Update exporter property key from 'otlp' to 'otel' by @lenguyenthanh in https://github.com/typelevel/otel4s/pull/1086
• Correct disabled TimerHeapConfig in docs by @lenguyenthanh in https://github.com/typelevel/otel4s/pull/1087

Dependencies

• Update cats-effect, cats-effect-kernel, ... to 3.6.3 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1022
• Update opentelemetry-proto to 1.8.0-alpha by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1054
• Update fs2-core, fs2-io, fs2-scodec to 3.12.2 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1060
• flake.lock: Update by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1092
• Update sbt, scripted-plugin to 1.11.7 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1111
• Update sbt-scalajs, scalajs-compiler, ... to 1.20.1 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1107
• Update http4s-circe, http4s-dsl, ... to 0.23.32 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1106
• Update pekko-stream to 1.2.1 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1105
• Update opentelemetry-javaagent to 2.20.1 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1104
• Update opentelemetry-instrumentation-annotations to 2.20.1 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1103
• Update scala3-library, ... to 3.3.7 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1109
• Update sbt-jmh to 0.4.8 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1113
• Update sbt-typelevel, ... to 0.8.2 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1112
• Update opentelemetry-api, ... to 1.55.0 by @typelevel-steward[bot] in https://github.com/typelevel/otel4s/pull/1115
• Update Otel4sAgentVersion to 0.0.4 by @iRevive in https://github.com/typelevel/otel4s/pull/1082

New Contributors

• @c0d33ngr made their first contribution in https://github.com/typelevel/otel4s/pull/1019
• @brbrown25 made their first contribution in https://github.com/typelevel/otel4s/pull/1096

Full Changelog: https://github.com/typelevel/otel4s/compare/v0.13.1...v0.14.0