Migrate Langfuse v1 to v2

Langfuse v2 (released Jan 30, 2024) is a major release of Langfuse that introduces a rebuilt usage and cost tracking system for LLM generations. The update requires running a one-off migration script on historical data to ensure accurate LLM costs of existing traces.

Changes

What has changed?

Completely rebuilt usage/cost tracking system for LLM generations
New model definition abstraction that enables:
- Quick support for new emerging models
- Tracking of model price changes over time
- Custom models/prices at the project level
Added ability to set usage and cost via API when ingesting traces
Usage and cost information available on all UI tables and APIs

What has not changed?

Everything else, including APIs and infrastructure components, remains the same. No breaking changes.

Who needs to take action during the upgrade?

No action required if you:
- Use Langfuse Cloud
- Only care about newly ingested traces
- Don't use the cost tracking features
Action required if you:
- Self-host Langfuse
- Want accurate cost data for historical traces

Migration Steps

This process is non-blocking and does not impact the availability of your Langfuse deployment.

Update Langfuse to v2

Follow the deployment guide to upgrade your Langfuse deployment to v2.

For production deployments, see the upgrade guide
If you use docker compose, see the upgrade guide

Apply new model logic and prices to existing data

Langfuse includes a list of supported models for usage and cost tracking. If a Langfuse update includes support for new models, these will only be applied to newly ingested traces/generations.

Optionally, you can apply the new model definitions to existing data using the following steps. During the migration, the database remains available (non-blocking).

Clone the repository and create an .env file:

# Clone the Langfuse repository
git clone https://github.com/langfuse/langfuse.git

# Navigate to the Langfuse directory
cd langfuse

# Checkout the Langfuse v2 branch
git checkout v2

# Install all dependencies
pnpm i

# Create an .env file
cp .env.dev.example .env

Edit the .env to connect to your database from your machine:

.env

NODE_ENV=production

# Replace with your database connection string
DATABASE_URL=postgresql://postgres:postgres@localhost:5432/postgres

Execute the migration. Depending on the size of your database, this might take a while.
```
pnpm run models:migrate
```
Clean up: remove the .env file to avoid connecting to the production database from your local machine.

If you experience any issues when self-hosting Langfuse, please:

Check out Troubleshooting & FAQ page.
Use Ask AI to get instant answers to your questions.
Ask the maintainers on GitHub Discussions.
Create a bug report or feature request on GitHub.

Enterprise-grade support is available when self-hosting Langfuse. Learn more on our pricing page.

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