Set Environment Variables | Boundary Documentation

Environment Variables in BAML

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

1 client<llm> GPT4o {
2   provider baml-openai-chat
3   options {
4     model gpt-5-mini
5     api_key env.OPENAI_API_KEY
6   }
7 }

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 Boundary Studio Integration

To send logs and traces to Boundary Studio, you need to set the BOUNDARY_API_KEY environment variable. This key is provided when you create an API key in your Boundary Studio dashboard.

Next.js

Express.js

Flask

Rails

$ # .env.local
> BOUNDARY_API_KEY=your_api_key_here

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

python

typescript

ruby

1 from dotenv import load_dotenv
2 from baml_client import b
3 
4 load_dotenv()

Boundary Studio Integration

When you use BAML in your application, logs and traces are automatically sent to Boundary Studio for monitoring and debugging. To enable this integration, you need to set the BOUNDARY_API_KEY environment variable with an API key from your Boundary Studio dashboard.

The API key is used to:

Authenticate your application with Boundary Studio
Associate logs and traces with your specific project and environment
Control access permissions for different operations