CloudWeGo Eino

Setup

Install the Braintrust Go SDK alongside the Eino packages, then configure your API keys.

Install packages

go get github.com/braintrustdata/braintrust-sdk-go
go get github.com/braintrustdata/braintrust-sdk-go/trace/contrib/cloudwego/eino
go get github.com/cloudwego/eino-ext/components/model/openai

Set environment variables

.env

BRAINTRUST_API_KEY=your-braintrust-api-key
OPENAI_API_KEY=your-openai-api-key

Auto-instrumentation

To trace Eino without wiring Braintrust into your application code, build your app with Orchestrion, a compile-time tool that appends Braintrust’s handler to your callbacks.AppendGlobalHandlers call. Once the handler is registered, all ChatModel, tool, and embedding calls are traced.

Install Orchestrion

go install github.com/DataDog/orchestrion@latest

Create orchestrion.tool.go in your project root

orchestrion.tool.go

//go:build tools

package main

import (
_ "github.com/DataDog/orchestrion"
_ "github.com/braintrustdata/braintrust-sdk-go/trace/contrib/cloudwego/eino"
)

Write your app

Register Eino’s global handlers with callbacks.AppendGlobalHandlers(). Orchestrion appends traceeino.DefaultHandler() to that call at build time, so you don’t import or construct the Braintrust handler yourself.

package main

import (
"context"
"fmt"
"log"
"os"

einoopenai "github.com/cloudwego/eino-ext/components/model/openai"
"github.com/cloudwego/eino/callbacks"
"github.com/cloudwego/eino/schema"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/sdk/trace"

"github.com/braintrustdata/braintrust-sdk-go"
)

func main() {
tp := trace.NewTracerProvider()
defer tp.Shutdown(context.Background())
otel.SetTracerProvider(tp)

bt, err := braintrust.New(tp,
	braintrust.WithProject("my-eino-project"),
	braintrust.WithAPIKey(os.Getenv("BRAINTRUST_API_KEY")),
)
if err != nil {
	log.Fatal(err)
}

// Orchestrion appends traceeino.DefaultHandler() to this call at build time.
callbacks.AppendGlobalHandlers()

ctx := context.Background()
tracer := otel.Tracer("eino-example")
ctx, span := tracer.Start(ctx, "eino-chat")
defer span.End()

chatModel, err := einoopenai.NewChatModel(ctx, &einoopenai.ChatModelConfig{
	Model:  "gpt-4o-mini",
	APIKey: os.Getenv("OPENAI_API_KEY"),
})
if err != nil {
	log.Fatal(err)
}

messages := []*schema.Message{{
	Role:    schema.User,
	Content: "What is the capital of France?",
}}
resp, err := chatModel.Generate(ctx, messages)
if err != nil {
	log.Fatal(err)
}

fmt.Printf("Response: %s\n", resp.Content)
fmt.Printf("View trace: %s\n", bt.Permalink(span))
}

Build with Orchestrion and run

go mod tidy
orchestrion go build -o myapp
./myapp

Enable Orchestrion via GOFLAGS

Instead of running orchestrion go build, you can set a GOFLAGS environment variable to enable Orchestrion for normal go build commands:

export GOFLAGS="-toolexec='orchestrion toolexec'"
go build ./...

Manual instrumentation

To trace Eino manually, register Braintrust’s handler yourself by passing traceeino.NewHandler() to callbacks.AppendGlobalHandlers. All subsequent ChatModel calls are traced.

package main

import (
	"context"
	"fmt"
	"log"
	"os"

	einoopenai "github.com/cloudwego/eino-ext/components/model/openai"
	"github.com/cloudwego/eino/callbacks"
	"github.com/cloudwego/eino/schema"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/sdk/trace"

	"github.com/braintrustdata/braintrust-sdk-go"
	traceeino "github.com/braintrustdata/braintrust-sdk-go/trace/contrib/cloudwego/eino"
)

func main() {
	tp := trace.NewTracerProvider()
	defer tp.Shutdown(context.Background())
	otel.SetTracerProvider(tp)

	bt, err := braintrust.New(tp,
		braintrust.WithProject("my-eino-project"),
		braintrust.WithAPIKey(os.Getenv("BRAINTRUST_API_KEY")),
	)
	if err != nil {
		log.Fatal(err)
	}

	handler := traceeino.NewHandler()
	callbacks.AppendGlobalHandlers(handler)

	ctx := context.Background()
	tracer := otel.Tracer("eino-example")
	ctx, span := tracer.Start(ctx, "eino-chat")
	defer span.End()

	chatModel, err := einoopenai.NewChatModel(ctx, &einoopenai.ChatModelConfig{
		Model:  "gpt-4o-mini",
		APIKey: os.Getenv("OPENAI_API_KEY"),
	})
	if err != nil {
		log.Fatal(err)
	}

	messages := []*schema.Message{{
		Role:    schema.User,
		Content: "What is the capital of France?",
	}}
	resp, err := chatModel.Generate(ctx, messages)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("Response: %s\n", resp.Content)
	fmt.Printf("View trace: %s\n", bt.Permalink(span))
}

Streaming

For streaming, call Wait() on the handler after closing the reader so asynchronously finalized span attributes are flushed before exit. Get the handler from traceeino.NewHandler() in the manual path, or from traceeino.DefaultHandler() when auto-instrumenting.

#skip-compile

reader, err := chatModel.Stream(ctx, messages)
if err != nil {
	log.Fatal(err)
}
// ... consume the stream ...
reader.Close()
handler.Wait()

Tracing embeddings

Eino’s callback handler captures EmbedStrings calls with no setup beyond registering the handler. Embedding calls appear as LLM spans in Braintrust, with input texts, embedding count, and model metadata captured.

What Braintrust traces

Braintrust captures:

Chat model spans (eino.<model>, for example eino.OpenAI), with input messages, model parameters (model, max_tokens, temperature, top_p, stop) in metadata, output message with finish reason and tool calls, and token usage metrics (prompt, completion, total, cached prompt, and reasoning tokens).
Streaming chat model output reconstructed from streamed chunks, with a time_to_first_token metric.
Tool spans (eino.<tool>), with the tool’s JSON arguments as input and its response as output.
Embedding spans (eino.<embedder>), with input texts, an embeddings count and vector length summary as output, model and encoding format in metadata, and prompt and total token metrics.

Resources

CloudWeGo Eino documentation
Go SDK example
Trace LLM calls for general Go auto-instrumentation setup

AI providers

SDKs

Developer tools

Setup

Auto-instrumentation

Manual instrumentation

Streaming

Tracing embeddings

What Braintrust traces

Resources

​Setup

​Auto-instrumentation

​Manual instrumentation

​Streaming

​Tracing embeddings

​What Braintrust traces

​Resources

Setup

Auto-instrumentation

Manual instrumentation

Streaming

Tracing embeddings

What Braintrust traces

Resources