06 Lambda Environment

title: Lambda Environment Configuration for Serverless APIs weight: 16 date: 2026-06-28 lastmod: 2026-06-28 description: Configure Lambda environment variables for serverless APIs including secrets management, environment-specific config, encryption with KMS, and best practices. tags: [api-development, serverless]

Lambda environment variables store configuration like database URLs, API keys, and feature flags, supporting encryption via AWS KMS, environment-specific values, and integration with Systems Manager Parameter Store for secrets.

```python
import os
import boto3
from botocore.exceptions import ClientError

# Access environment variables
DATABASE_URL = os.environ.get("DATABASE_URL")
LOG_LEVEL = os.environ.get("LOG_LEVEL", "INFO")
STAGE = os.environ.get("STAGE", "dev")

# Get secret from Parameter Store
def get_secret(secret_name):
    ssm = boto3.client("ssm")
    try:
        response = ssm.get_parameter(
            Name=secret_name,
            WithDecryption=True
        )
        return response["Parameter"]["Value"]
    except ClientError as e:
        print(f"Error fetching secret: {e}")
        return None

DB_PASSWORD = get_secret(f"/myapp/{STAGE}/db_password")

What's Next

Now learn about API Gateway Lambda integration in Building Serverless APIs.