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Merge pull request #24 from braintrustdata/ark/langchain4j-instrumentation
Instrumentation for Lanchain4j's OpenAI Chat Model
2 parents 1db1ece + f09d73b commit 1b58fef

8 files changed

Lines changed: 912 additions & 1 deletion

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‎build.gradle‎

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@@ -46,6 +46,7 @@ ext {
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jacksonVersion = '2.16.1'
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junitVersion = '5.11.4'
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slf4jVersion = '2.0.17'
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langchainVersion = '1.9.1'
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}
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dependencies {
@@ -86,6 +87,14 @@ dependencies {
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// Google GenAI Instrumentation
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compileOnly "com.google.genai:google-genai:1.20.0"
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testImplementation "com.google.genai:google-genai:1.20.0"
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// LangChain4j Instrumentation
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compileOnly "dev.langchain4j:langchain4j:${langchainVersion}"
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compileOnly "dev.langchain4j:langchain4j-http-client:${langchainVersion}"
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compileOnly "dev.langchain4j:langchain4j-open-ai:${langchainVersion}"
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testImplementation "dev.langchain4j:langchain4j:${langchainVersion}"
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testImplementation "dev.langchain4j:langchain4j-http-client:${langchainVersion}"
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testImplementation "dev.langchain4j:langchain4j-open-ai:${langchainVersion}"
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}
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/**

‎examples/build.gradle‎

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@@ -35,6 +35,9 @@ dependencies {
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implementation('org.springframework.boot:spring-boot-starter:3.4.1') {
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exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
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}
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// to run langchain4j examples
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implementation 'dev.langchain4j:langchain4j:1.9.1'
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implementation 'dev.langchain4j:langchain4j-open-ai:1.9.1'
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}
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application {
@@ -142,7 +145,6 @@ task runSpringAI(type: JavaExec) {
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}
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}
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task runRemoteEval(type: JavaExec) {
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group = 'Braintrust SDK Examples'
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description = 'Run the remote eval example'
@@ -156,3 +158,17 @@ task runRemoteEval(type: JavaExec) {
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suspend = false
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}
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}
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task runLangchain(type: JavaExec) {
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group = 'Braintrust SDK Examples'
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description = 'Run the LangChain4j instrumentation example. NOTE: this requires OPENAI_API_KEY to be exported and will make a small call to openai, using your tokens'
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classpath = sourceSets.main.runtimeClasspath
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mainClass = 'dev.braintrust.examples.LangchainExample'
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systemProperty 'org.slf4j.simpleLogger.log.dev.braintrust', braintrustLogLevel
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debugOptions {
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enabled = true
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port = 5566
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server = true
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suspend = false
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}
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}

‎examples/src/main/java/dev/braintrust/examples/LangchainExample.java‎

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@@ -0,0 +1,54 @@
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package dev.braintrust.examples;
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import dev.braintrust.Braintrust;
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import dev.braintrust.instrumentation.langchain.BraintrustLangchain;
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import dev.langchain4j.data.message.UserMessage;
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import dev.langchain4j.model.chat.ChatModel;
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import dev.langchain4j.model.openai.OpenAiChatModel;
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/** Basic OTel + LangChain4j instrumentation example */
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public class LangchainExample {
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public static void main(String[] args) throws Exception {
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if (null == System.getenv("OPENAI_API_KEY")) {
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System.err.println(
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"\nWARNING envar OPENAI_API_KEY not found. This example will likely fail.\n");
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}
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var braintrust = Braintrust.get();
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var openTelemetry = braintrust.openTelemetryCreate();
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ChatModel model =
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BraintrustLangchain.wrap(
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openTelemetry,
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OpenAiChatModel.builder()
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.apiKey(System.getenv("OPENAI_API_KEY"))
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.modelName("gpt-4o-mini")
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.temperature(0.0));
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var rootSpan =
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openTelemetry
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.getTracer("my-instrumentation")
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.spanBuilder("langchain4j-instrumentation-example")
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.startSpan();
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try (var ignored = rootSpan.makeCurrent()) {
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chatExample(model);
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} finally {
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rootSpan.end();
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}
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var url =
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braintrust.projectUri()
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+ "/logs?r=%s&s=%s"
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.formatted(
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rootSpan.getSpanContext().getTraceId(),
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rootSpan.getSpanContext().getSpanId());
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System.out.println(
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"\n\n Example complete! View your data in Braintrust: %s\n".formatted(url));
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}
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private static void chatExample(ChatModel model) {
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var message = UserMessage.from("What is the capital of France?");
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var response = model.chat(message);
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System.out.println(
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"\n~~~ LANGCHAIN4J CHAT RESPONSE: %s\n".formatted(response.aiMessage().text()));
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}
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}

‎src/main/java/dev/braintrust/instrumentation/langchain/BraintrustLangchain.java‎

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package dev.braintrust.instrumentation.langchain;
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import dev.langchain4j.http.client.HttpClientBuilder;
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import dev.langchain4j.http.client.HttpClientBuilderLoader;
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import dev.langchain4j.model.openai.OpenAiChatModel;
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import dev.langchain4j.model.openai.OpenAiStreamingChatModel;
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import io.opentelemetry.api.OpenTelemetry;
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import lombok.extern.slf4j.Slf4j;
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/** Braintrust LangChain4j client instrumentation. */
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@Slf4j
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public final class BraintrustLangchain {
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/** Instrument langchain openai chat model with braintrust traces */
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public static OpenAiChatModel wrap(
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OpenTelemetry otel, OpenAiChatModel.OpenAiChatModelBuilder builder) {
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try {
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HttpClientBuilder underlyingHttpClient = getPrivateField(builder, "httpClientBuilder");
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if (underlyingHttpClient == null) {
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underlyingHttpClient = HttpClientBuilderLoader.loadHttpClientBuilder();
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}
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HttpClientBuilder wrappedHttpClient =
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wrap(otel, underlyingHttpClient, new Options("openai"));
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return builder.httpClientBuilder(wrappedHttpClient).build();
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} catch (Exception e) {
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log.warn(
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"Braintrust instrumentation could not be applied to OpenAiChatModel builder",
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e);
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return builder.build();
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}
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}
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/** Instrument langchain openai chat model with braintrust traces */
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public static OpenAiStreamingChatModel wrap(
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OpenTelemetry otel, OpenAiStreamingChatModel.OpenAiStreamingChatModelBuilder builder) {
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try {
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HttpClientBuilder underlyingHttpClient = getPrivateField(builder, "httpClientBuilder");
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if (underlyingHttpClient == null) {
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underlyingHttpClient = HttpClientBuilderLoader.loadHttpClientBuilder();
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}
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HttpClientBuilder wrappedHttpClient =
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wrap(otel, underlyingHttpClient, new Options("openai"));
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return builder.httpClientBuilder(wrappedHttpClient).build();
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} catch (Exception e) {
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log.warn(
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"Braintrust instrumentation could not be applied to OpenAiStreamingChatModel"
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+ " builder",
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e);
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return builder.build();
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}
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}
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private static HttpClientBuilder wrap(
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OpenTelemetry otel, HttpClientBuilder builder, Options options) {
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return new WrappedHttpClientBuilder(otel, builder, options);
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}
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public record Options(String providerName) {}
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@SuppressWarnings("unchecked")
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private static <T> T getPrivateField(Object obj, String fieldName)
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throws ReflectiveOperationException {
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java.lang.reflect.Field field = obj.getClass().getDeclaredField(fieldName);
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field.setAccessible(true);
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return (T) field.get(obj);
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}
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}

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