Set Environment Variables

Environment Variables in BAML

Sometimes you’ll see environment variables used in BAML, like in clients:

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client<llm> GPT4o {
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  provider baml-openai-chat
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  options {
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    model gpt-4o
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    api_key env.OPENAI_API_KEY
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  }
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}

Setting Environment Variables

In the VSCode Playground

Once you open a .baml file in VSCode, you should see a small button over every BAML function: Open Playground. Then you should be able to set environment variables in the settings tab.

Or type BAML Playground in the VSCode Command Bar (CMD + Shift + P or CTRL + Shift + P) to open the playground.

For Your App (Default)

BAML will do its best to load environment variables from your program. Any of the following strategies for setting env vars are compatible with BAML:

• Setting them in your shell before running your program
• In your Dockerfile
• In your next.config.js
• In your Kubernetes manifest
• From secrets-store.csi.k8s.io
• From a secrets provider such as Infisical / Doppler
• From a .env file (using dotenv CLI)
• Using account credentials for ephemeral token generation (e.g., Vertex AI Auth Tokens)
• python-dotenv package in Python or dotenv package in Node.js

$
export MY_SUPER_SECRET_API_KEY="..."
>
python my_program_using_baml.py

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import dotenv
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from baml_client import b
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# This will work regardless of import order, since dotenv is imported as a module
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dotenv.load_dotenv()

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from baml_client import b
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from dotenv import load_dotenv
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# This will work since load_dotenv is imported after baml_client
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load_dotenv()

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from dotenv import load_dotenv
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from baml_client import b
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# This will not work as expected since baml_client is imported AFTER load_dotenv
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load_dotenv()

For Your App (Manually)

Reset the environment variables to those manually set in your code.

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from baml_client import b
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from baml_client.config import reset_baml_env_vars
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# This will load the environment variables from the .env file
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reset_baml_env_vars({ "OPENAI_API_KEY": "sk-super-secret-key" })

Setting LLM API Keys per Request

You can set the API key for an LLM dynamically by passing in the key as a header or as a parameter (depending on the provider), using the ClientRegistry.