Exporters

Langfuse

Langfuse is an open-source LLM engineering platform for observability, metrics, evaluations, and prompt management.

Property	Type	Required	Default	Environment Variable	Description
langfuseUrl	String?	No	https://cloud.langfuse.com	LANGFUSE_URL	Langfuse server URL
langfusePublicKey	String?	Yes	-	LANGFUSE_PUBLIC_KEY	Langfuse public API key
langfuseSecretKey	String?	Yes	-	LANGFUSE_SECRET_KEY	Langfuse secret API key
exporterTimeoutSeconds	Long	No	10	-	Timeout for span export (seconds)
settings	ExporterCommonSettings	No	ExporterCommonSettings()	-	Common exporter settings

Example

// Using environment variables
// (don't forget to set `LANGFUSE_URL`, `LANGFUSE_PUBLIC_KEY`, and `LANGFUSE_SECRET_KEY` env variables)
val sdk = configureOpenTelemetrySdk(LangfuseExporterConfig())

// Or with explicit configuration
val sdkExplicit = configureOpenTelemetrySdk(
    LangfuseExporterConfig(
        langfuseUrl = "https://cloud.langfuse.com",
        langfusePublicKey = "pk-lf-...",
        langfuseSecretKey = "sk-lf-...",
        exporterTimeoutSeconds = 15,
        settings = ExporterCommonSettings(
            traceToConsole = true // Also log to console for debugging
        )
    )
)

TracingManager.setSdk(sdk)

See the full example: LangfuseExample.kt

---

Weave (Weights & Biases)

W&B Weave is the Weights & Biases platform for LLM application tracing and evaluation.

Property	Type	Required	Default	Environment Variable	Description
weaveUrl	String?	No	https://trace.wandb.ai	WEAVE_URL	Weave OTLP endpoint URL
weaveEntity	String?	Yes	-	WEAVE_ENTITY	W&B entity (team/org) name
weaveProjectName	String?	Yes	-	WEAVE_PROJECT_NAME	W&B project name
weaveApiKey	String?	Yes	-	WEAVE_API_KEY	W&B API key
exporterTimeoutSeconds	Long	No	10	-	Timeout for span export (seconds)
settings	ExporterCommonSettings	No	ExporterCommonSettings()	-	Common exporter settings

Example

// Using environment variables
// (don't forget to set `WEAVE_URL`, `WEAVE_ENTITY`, `WEAVE_PROJECT_NAME`, `WEAVE_API_KEY` env variables)
val sdk = configureOpenTelemetrySdk(WeaveExporterConfig())

// Or with explicit configuration
val sdkExplicit = configureOpenTelemetrySdk(
    WeaveExporterConfig(
        weaveUrl = "https://trace.wandb.ai",
        weaveEntity = "my-team",
        weaveProjectName = "my-ai-project",
        weaveApiKey = "your-wandb-api-key",
        exporterTimeoutSeconds = 15,
        settings = ExporterCommonSettings(
            traceToConsole = true
        )
    )
)

TracingManager.setSdk(sdk)

See the full example: WeaveExample.kt

---

OTLP HTTP

Export spans to any OTLP HTTP-compatible collector such as Jaeger, Grafana Tempo, or other OpenTelemetry backends.

Property	Type	Required	Default	Description
url	String	Yes	-	Base URL of the OTLP HTTP collector endpoint
exporterTimeoutSeconds	Long	No	10	Timeout for span export (seconds)
settings	ExporterCommonSettings	No	ExporterCommonSettings()	Common exporter settings

The exporter automatically appends /v1/traces to the provided URL.

Example (Jaeger)

// Export to Jaeger running locally
val sdk = configureOpenTelemetrySdk(
    OtlpHttpExporterConfig(
        url = "http://localhost:4318",
        exporterTimeoutSeconds = 10,
        settings = ExporterCommonSettings(
            traceToConsole = true
        )
    )
)

TracingManager.setSdk(sdk)

See the full example: JaegerExporterExample.kt

---

Console

Export traces to the console for local development and debugging.

Property	Type	Required	Default	Description
format	OutputFormat	No	OutputFormat.PLAIN_TEXT	Output format (PLAIN_TEXT or JSON)
settings	ExporterCommonSettings	No	ExporterCommonSettings()	Common exporter settings

Output Format

The OutputFormat enum controls the format for Console and File exporters:

Value	Description
OutputFormat.PLAIN_TEXT	Human-readable plain text format (default)
OutputFormat.JSON	OTLP JSON format for structured logging

Use JSON if you will analyze your traces programmatically; otherwise, use plain text (the default).

Example

// Plain text output (default)
val sdk = configureOpenTelemetrySdk(ConsoleExporterConfig())

// JSON output
val jsonSdk = configureOpenTelemetrySdk(
    ConsoleExporterConfig(format = OutputFormat.JSON)
)

TracingManager.setSdk(sdk)

---

File

Export traces to a file for offline analysis or log aggregation.

Property	Type	Required	Default	Description
filepath	String	Yes	-	File path where traces will be written
append	Boolean	Yes	-	true to append to existing file, false to overwrite
format	OutputFormat	No	OutputFormat.PLAIN_TEXT	Output format (PLAIN_TEXT or JSON)
settings	ExporterCommonSettings	No	ExporterCommonSettings()	Common exporter settings

Example

// Plain text file
val sdk = configureOpenTelemetrySdk(
    FileExporterConfig(
        filepath = "/var/log/traces.log",
        append = true
    )
)

// JSON Lines file (one JSON object per line)
val jsonSdk = configureOpenTelemetrySdk(
    FileExporterConfig(
        filepath = "/var/log/traces.jsonl",
        append = true,
        format = OutputFormat.JSON
    )
)

TracingManager.setSdk(sdk)

See the full example: FileTracingExample.kt