gh-k-dense-ai-claude-scientific-skills-scientific-skills/skills/modal/references/secrets.md

Secrets and Environment Variables

Creating Secrets

Via Dashboard

Create secrets at https://modal.com/secrets

Templates available for:

• Database credentials (Postgres, MongoDB)
• Cloud providers (AWS, GCP, Azure)
• ML platforms (Weights & Biases, Hugging Face)
• And more

Via CLI

# Create secret with key-value pairs
modal secret create my-secret KEY1=value1 KEY2=value2

# Use environment variables
modal secret create db-secret PGHOST=uri PGPASSWORD="$PGPASSWORD"

# List secrets
modal secret list

# Delete secret
modal secret delete my-secret

Programmatically

From dictionary:

if modal.is_local():
    local_secret = modal.Secret.from_dict({"FOO": os.environ["LOCAL_FOO"]})
else:
    local_secret = modal.Secret.from_dict({})

@app.function(secrets=[local_secret])
def some_function():
    import os
    print(os.environ["FOO"])

From .env file:

@app.function(secrets=[modal.Secret.from_dotenv()])
def some_function():
    import os
    print(os.environ["USERNAME"])

Using Secrets

Inject secrets into functions:

@app.function(secrets=[modal.Secret.from_name("my-secret")])
def some_function():
    import os
    secret_key = os.environ["MY_PASSWORD"]
    # Use secret
    ...

Multiple Secrets

@app.function(secrets=[
    modal.Secret.from_name("database-creds"),
    modal.Secret.from_name("api-keys"),
])
def other_function():
    # All keys from both secrets available
    ...

Later secrets override earlier ones if keys clash.

Environment Variables

Reserved Runtime Variables

All Containers:

• MODAL_CLOUD_PROVIDER - Cloud provider (AWS/GCP/OCI)
• MODAL_IMAGE_ID - Image ID
• MODAL_REGION - Region identifier (e.g., us-east-1)
• MODAL_TASK_ID - Container task ID

Function Containers:

• MODAL_ENVIRONMENT - Modal Environment name
• MODAL_IS_REMOTE - Set to '1' in remote containers
• MODAL_IDENTITY_TOKEN - OIDC token for function identity

Sandbox Containers:

• MODAL_SANDBOX_ID - Sandbox ID

Setting Environment Variables

Via Image:

image = modal.Image.debian_slim().env({"PORT": "6443"})

@app.function(image=image)
def my_function():
    import os
    port = os.environ["PORT"]

Via Secrets:

secret = modal.Secret.from_dict({"API_KEY": "secret-value"})

@app.function(secrets=[secret])
def my_function():
    import os
    api_key = os.environ["API_KEY"]

Common Secret Patterns

AWS Credentials

aws_secret = modal.Secret.from_name("my-aws-secret")

@app.function(secrets=[aws_secret])
def use_aws():
    import boto3
    s3 = boto3.client('s3')
    # AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY automatically used

Hugging Face Token

hf_secret = modal.Secret.from_name("huggingface")

@app.function(secrets=[hf_secret])
def download_model():
    from transformers import AutoModel
    # HF_TOKEN automatically used for authentication
    model = AutoModel.from_pretrained("private-model")

Database Credentials

db_secret = modal.Secret.from_name("postgres-creds")

@app.function(secrets=[db_secret])
def query_db():
    import psycopg2
    conn = psycopg2.connect(
        host=os.environ["PGHOST"],
        port=os.environ["PGPORT"],
        user=os.environ["PGUSER"],
        password=os.environ["PGPASSWORD"],
    )

Best Practices

1. Never hardcode secrets - Always use Modal Secrets
2. Use specific secrets - Create separate secrets for different purposes
3. Rotate secrets regularly - Update secrets periodically
4. Minimal scope - Only attach secrets to functions that need them
5. Environment-specific - Use different secrets for dev/staging/prod

Security Notes

• Secrets are encrypted at rest
• Only available to functions that explicitly request them
• Not logged or exposed in dashboards
• Can be scoped to specific environments