BerriAI/litellm · error · ValueError

LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY must be set for

Error message

LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY must be set for Langfuse OpenTelemetry integration.

What it means

LangfuseOtelLogger.get_config reads LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY directly from os.environ and raises ValueError if either is unset or empty. Unlike the HTTP logger, the OpenTelemetry-based integration does not accept credentials as constructor arguments or per-request params — env vars are mandatory.

Source

Thrown at litellm/integrations/langfuse/langfuse_otel.py:301

        """
        Retrieves the Langfuse OpenTelemetry configuration based on environment variables.

        Environment Variables:
            LANGFUSE_PUBLIC_KEY: Required. Langfuse public key for authentication.
            LANGFUSE_SECRET_KEY: Required. Langfuse secret key for authentication.
            LANGFUSE_HOST: Optional. Custom Langfuse host URL. Defaults to US cloud.

        Returns:
            OpenTelemetryConfig: A Pydantic model containing Langfuse OTEL configuration.

        Raises:
            ValueError: If required keys are missing.
        """
        public_key: Final = os.environ.get("LANGFUSE_PUBLIC_KEY", None)
        secret_key: Final = os.environ.get("LANGFUSE_SECRET_KEY", None)

        if not public_key or not secret_key:
            raise ValueError(
                "LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY must be set for Langfuse OpenTelemetry integration."
            )

        return LangfuseOtelLogger._build_langfuse_otel_config(
            public_key=public_key,
            secret_key=secret_key,
            langfuse_host=LangfuseOtelLogger._get_langfuse_otel_host(),
        )

    @staticmethod
    def _build_langfuse_otel_config(
        public_key: str, secret_key: str, langfuse_host: str | None
    ) -> "OpenTelemetryConfig":
        """
        Builds an OTLP HTTP config pointing at the Langfuse OTEL endpoint for the
        given host (US cloud when no host is provided), authorized with the given keys.
        """
        if langfuse_host:

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. export LANGFUSE_PUBLIC_KEY=pk-lf-... and export LANGFUSE_SECRET_KEY=sk-lf-... in the environment of the litellm process
2. In Docker/K8s, verify with 'env | grep LANGFUSE' inside the running container — secrets may exist locally but not in the pod spec
3. Optionally set LANGFUSE_HOST if not using the US cloud
4. If secrets are managed via a vault, inject them as env vars before litellm imports/initializes the OTEL logger

Example fix

# before
litellm_settings:
  opentelemetry: true  # ValueError: LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY must be set...

# after
# environment:
#   LANGFUSE_PUBLIC_KEY=pk-lf-xxx
#   LANGFUSE_SECRET_KEY=sk-lf-xxx
litellm_settings:
  opentelemetry: true

import os

_REQUIRED = ("LANGFUSE_PUBLIC_KEY", "LANGFUSE_SECRET_KEY")
missing = [k for k in _REQUIRED if not os.environ.get(k)]
if missing:
    raise RuntimeError(f"Set env vars before enabling Langfuse OTEL: {missing}")

When it happens

Trigger: Enabling litellm_settings.opentelemetry with the Langfuse OTEL exporter (or calling LangfuseOtelLogger.get_config()) without exporting both env vars; setting only one of the two keys; exporting them in a different shell/container than the one running litellm.

Common situations: Docker/Kubernetes deployments where the env vars were added to the image but not the deployment spec (or vice versa); CI pipelines that only set LANGFUSE_PUBLIC_KEY; migrating from the legacy langfuse callback (which resolves credentials differently) to the OTEL integration.

Related errors

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• Missing keys={missing_keys} in environment.

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/9c031d51e85e53c8. Report an issue: GitHub.