langflow/docs/docs/Configuration/configuration-custom-database.md

title	slug
Configure an external PostgreSQL database	/configuration-custom-database

Langflow's default database is SQLite, but you can configure Langflow to use PostgreSQL instead.

This guide walks you through setting up an external database for Langflow by replacing the default SQLite connection string sqlite:///./langflow.db with PostgreSQL.

Prerequisite

• A PostgreSQL database

Connect Langflow to PostgreSQL

To connect Langflow to PostgreSQL, follow these steps.

1. Find your PostgreSQL database's connection string. It looks like postgresql://user:password@host:port/dbname.

The hostname in your connection string depends on how you're running PostgreSQL.

• If you're running PostgreSQL directly on your machine, use localhost.
• If you're running PostgreSQL in Docker Compose, use the service name, such as postgres.
• If you're running PostgreSQL in a separate Docker container with docker run, use the container's IP address or network alias.

2. Create a .env file for configuring Langflow.

touch .env

3. To set the database URL environment variable, add it to your .env file:

LANGFLOW_DATABASE_URL="postgresql://user:password@localhost:5432/dbname"

:::tip The Langflow project includes a .env.example file to help you get started. You can copy the contents of this file into your own .env file and replace the example values with your own preferred settings. Replace the value for LANGFLOW_DATABASE_URL with your PostgreSQL connection string. :::

4. Run Langflow with the .env file:

uv run langflow run --env-file .env

5. In Langflow, create traffic by running a flow.
6. Inspect your PostgreSQL deployment's tables and activity. New tables and traffic are created.

Example Langflow and PostgreSQL docker-compose.yml

The Langflow project includes a docker-compose.yml file for quick deployment with PostgreSQL.

This configuration launches Langflow and PostgreSQL containers in the same Docker network, ensuring proper connectivity between services. It also sets up persistent volumes for both Langflow and PostgreSQL data.

To start the services, navigate to the /docker_example directory, and then run docker-compose up.

services:
  langflow:
    image: langflowai/langflow:latest    # or another version tag on https://hub.docker.com/r/langflowai/langflow
    pull_policy: always                   # set to 'always' when using 'latest' image
    ports:
      - "7860:7860"
    depends_on:
      - postgres
    environment:
      - LANGFLOW_DATABASE_URL=postgresql://langflow:langflow@postgres:5432/langflow
      # This variable defines where the logs, file storage, monitor data, and secret keys are stored.
      - LANGFLOW_CONFIG_DIR=app/langflow
    volumes:
      - langflow-data:/app/langflow

  postgres:
    image: postgres:16
    environment:
      POSTGRES_USER: langflow
      POSTGRES_PASSWORD: langflow
      POSTGRES_DB: langflow
    ports:
      - "5432:5432"
    volumes:
      - langflow-postgres:/var/lib/postgresql/data

volumes:
  langflow-postgres:    # Persistent volume for PostgreSQL data
  langflow-data:        # Persistent volume for Langflow data

:::note Docker Compose creates an isolated network for all services defined in the docker-compose.yml file. This ensures that the services can communicate with each other using their service names as hostnames, for example, postgres in the database URL. If you were to run PostgreSQL separately using docker run, it would be in a different network and Langflow wouldn't be able to connect to it using the service name. :::

Deploy multiple Langflow instances with a shared database

To configure multiple Langflow instances that share the same PostgreSQL database, modify your docker-compose.yml file to include multiple Langflow services.

Use environment variables for more centralized configuration management:

1. Update your .env file with values for your PostgreSQL database:

POSTGRES_USER=langflow
POSTGRES_PASSWORD=your_secure_password
POSTGRES_DB=langflow
POSTGRES_HOST=postgres
POSTGRES_PORT=5432
LANGFLOW_CONFIG_DIR=app/langflow
LANGFLOW_PORT_1=7860
LANGFLOW_PORT_2=7861
LANGFLOW_HOST=0.0.0.0

2. Reference these variables in your docker-compose.yml:

services:
  postgres:
    image: postgres:16
    environment:
      - POSTGRES_USER=${POSTGRES_USER}
      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
      - POSTGRES_DB=${POSTGRES_DB}
    ports:
      - "${POSTGRES_PORT}:5432"
    volumes:
      - langflow-postgres:/var/lib/postgresql/data

  langflow-1:
    image: langflowai/langflow:latest
    pull_policy: always
    ports:
      - "${LANGFLOW_PORT_1}:7860"
    depends_on:
      - postgres
    environment:
      - LANGFLOW_DATABASE_URL=postgresql://${POSTGRES_USER}:${POSTGRES_PASSWORD}@${POSTGRES_HOST}:${POSTGRES_PORT}/${POSTGRES_DB}
      - LANGFLOW_CONFIG_DIR=${LANGFLOW_CONFIG_DIR}
      - LANGFLOW_HOST=${LANGFLOW_HOST}
      - PORT=7860
    volumes:
      - langflow-data-1:/app/langflow

  langflow-2:
    image: langflowai/langflow:latest
    pull_policy: always
    ports:
      - "${LANGFLOW_PORT_2}:7860"
    depends_on:
      - postgres
    environment:
      - LANGFLOW_DATABASE_URL=postgresql://${POSTGRES_USER}:${POSTGRES_PASSWORD}@${POSTGRES_HOST}:${POSTGRES_PORT}/${POSTGRES_DB}
      - LANGFLOW_CONFIG_DIR=${LANGFLOW_CONFIG_DIR}
      - LANGFLOW_HOST=${LANGFLOW_HOST}
      - PORT=7860
    volumes:
      - langflow-data-2:/app/langflow

volumes:
  langflow-postgres:
  langflow-data-1:
  langflow-data-2:

3. Deploy the file with docker-compose up. You can access the first Langflow instance at http://localhost:7860, and the second Langflow instance at http://localhost:7861.

4. To confirm both instances are using the same database, run the docker exec command to start psql in your PostgreSQL container. Your container name may vary.

docker exec -it docker-test-postgres-1 psql -U langflow -d langflow

5. Query the database for active connections:

langflow=# SELECT * FROM pg_stat_activity WHERE datname = 'langflow';

6. Examine the query results for multiple connections with different client_addr values, for example 172.21.0.3 and 172.21.0.4.

Since each Langflow instance runs in its own container on the Docker network, using different incoming IP addresses confirms that both instances are actively connected to the PostgreSQL database.

7. To quit psql, type quit.