Langfuse Data Handling

Langfuse Data Handling

Overview

Manage the Langfuse data lifecycle: export traces and scores via the API, configure retention policies, handle GDPR data subject requests, anonymize data for analytics, and maintain audit trails.

Prerequisites

• @langfuse/​client installed
• Langfuse API keys with appropriate permissions
• Understanding of your compliance requirements (GDPR, SOC2, HIPAA)

Instructions

Step 1: Export Trace Data via API

import { LangfuseClient } from "@langfuse/​client";
import { writeFileSync } from "fs";

const langfuse = new LangfuseClient();

async function exportTraces(options: {
  fromDate: string;
  toDate: string;
  outputFile: string;
  includeObservations?: boolean;
}) {
  const allTraces: any[] = [];
  let page = 1;
  let hasMore = true;

  while (hasMore) {
    const result = await langfuse.api.traces.list({
      fromTimestamp: options.fromDate,
      toTimestamp: options.toDate,
      limit: 100,
      page,
    });

    for (const trace of result.data) {
      const exportItem: any = {
        id: trace.id,
        name: trace.name,
        timestamp: trace.timestamp,
        userId: trace.userId,
        sessionId: trace.sessionId,
        metadata: trace.metadata,
        tags: trace.tags,
      };

      if (options.includeObservations) {
        const observations = await langfuse.api.observations.list({
          traceId: trace.id,
        });
        exportItem.observations = observations.data;
      }

      allTraces.push(exportItem);
    }

    hasMore = result.data.length === 100;
    page++;

    // Rate limit respect
    await new Promise((r) => setTimeout(r, 200));
  }

  writeFileSync(options.outputFile, JSON.stringify(allTraces, null, 2));
  console.log(`Exported ${allTraces.length} traces to ${options.outputFile}`);
}

// Usage
await exportTraces({
  fromDate: "2025-01-01T00:00:00Z",
  toDate: "2025-01-31T23:59:59Z",
  outputFile: "traces-january.json",
  includeObservations: true,
});

Step 2: Export Scores

async function exportScores(fromDate: string, outputFile: string) {
  const scores: any[] = [];
  let page = 1;
  let hasMore = true;

  while (hasMore) {
    const result = await langfuse.api.scores.list({
      fromTimestamp: fromDate,
      limit: 100,
      page,
    });

    scores.push(...result.data);
    hasMore = result.data.length === 100;
    page++;
    await new Promise((r) => setTimeout(r, 200));
  }

  writeFileSync(outputFile, JSON.stringify(scores, null, 2));
  console.log(`Exported ${scores.length} scores to ${outputFile}`);
}

Step 3: Data Retention Configuration

Self-hosted: Set retention via environment variable:

# docker-compose.yml
services:
  langfuse:
    environment:
      - LANGFUSE_RETENTION_DAYS=90

Cloud: Programmatic cleanup of old data:

async function enforceRetention(maxAgeDays: number) {
  const cutoff = new Date(Date.now() - maxAgeDays * 86400000).toISOString();

  const oldTraces = await langfuse.api.traces.list({
    toTimestamp: cutoff,
    limit: 100,
  });

  console.log(`Found ${oldTraces.data.length} traces older than ${maxAgeDays} days`);

  for (const trace of oldTraces.data) {
    await langfuse.api.traces.delete(trace.id);
    await new Promise((r) => setTimeout(r, 100)); // Rate limit
  }
}

// Run as cron job
await enforceRetention(90);

Step 4: GDPR Data Subject Requests

// Handle "Right to Access" -- export all data for a user
async function handleAccessRequest(userId: string) {
  const traces = await langfuse.api.traces.list({
    userId,
    limit: 1000,
  });

  const userData = {
    userId,
    exportDate: new Date().toISOString(),
    traceCount: traces.data.length,
    traces: traces.data.map((t) => ({
      id: t.id,
      name: t.name,
      timestamp: t.timestamp,
      input: t.input,
      output: t.output,
      metadata: t.metadata,
    })),
  };

  writeFileSync(`gdpr-export-${userId}.json`, JSON.stringify(userData, null, 2));
  return userData;
}

// Handle "Right to Erasure" -- delete all data for a user
async function handleDeletionRequest(userId: string) {
  const traces = await langfuse.api.traces.list({
    userId,
    limit: 1000,
  });

  let deleted = 0;
  for (const trace of traces.data) {
    await langfuse.api.traces.delete(trace.id);
    deleted++;
    await new Promise((r) => setTimeout(r, 100));
  }

  console.log(`Deleted ${deleted} traces for user ${userId}`);
  return { userId, tracesDeleted: deleted };
}

Step 5: Data Anonymization for Analytics

import crypto from "crypto";

function anonymizeTrace(trace: any): any {
  return {
    ...trace,
    userId: trace.userId ? crypto.createHash("sha256").update(trace.userId).digest("hex").slice(0, 16) : null,
    sessionId: trace.sessionId ? crypto.createHash("sha256").update(trace.sessionId).digest("hex").slice(0, 16) : null,
    input: "[REDACTED]",
    output: "[REDACTED]",
    metadata: {
      model: trace.metadata?.model,
      // Keep operational fields, remove PII
    },
  };
}

async function exportAnonymized(fromDate: string, outputFile: string) {
  const traces = await langfuse.api.traces.list({
    fromTimestamp: fromDate,
    limit: 1000,
  });

  const anonymized = traces.data.map(anonymizeTrace);
  writeFileSync(outputFile, JSON.stringify(anonymized, null, 2));
}

Data Categories and Retention

Error Handling

Resources

• Langfuse Data Security
• Public API Reference
• API Reference (OpenAPI)
• Self-Hosting Configuration