Let me help you understand how to use environment variables from a .env file in your YAML-based deployments. Here's a comprehensive guide: 1. Create your .env file

env
DATABASE_URL=<postgresql://user:pass@localhost:5432/db>
API_KEY=your-secret-key

2. Load the .env file You'll need to ensure your .env file is loaded before running Prefect commands. You can do this in two ways: a. Using python-dotenv in your deployment script:

python
from dotenv import load_dotenv
load_dotenv()

b. Or using the

python-dotenv

CLI when running commands:

bash
dotenv run prefect deploy

3. Reference environment variables in prefect.yaml Use the

{{ $ENV_VAR_NAME }}

syntax to reference environment variables:

yaml
deployments:
  - name: my-deployment
    entrypoint: flow.py:my_flow
    work_pool:
      name: my-pool
    job:
      variables:
        DATABASE_URL: "{{ $DATABASE_URL }}"
        API_KEY: "{{ $API_KEY }}"

4. Deploy your flow When you run

prefect deploy

, Prefect will automatically substitute the environment variables from your local environment into the deployment configuration. Important Notes: - Environment variables must be present in the environment when you run

prefect deploy

- The values will be stored securely in the Prefect database - You can mix static values and environment variables in your

prefect.yaml

- For sensitive values, consider using Prefect Blocks instead, especially for credentials Example with mixed static and environment variables:

yaml
deployments:
  - name: my-deployment
    entrypoint: flow.py:my_flow
    work_pool:
      name: my-pool
    job:
      variables:
        DATABASE_URL: "{{ $DATABASE_URL }}"
        API_KEY: "{{ $API_KEY }}"
        RETRY_ATTEMPTS: 3  # static value
        ENVIRONMENT: "production"  # static value

For more details and advanced configurations, you can refer to: - Customizing Job Variables Documentation - Prefect YAML Configuration Guide Let me know if you need any clarification or have questions about specific use cases!