Both environment variables and the AWS Systems Manager (SSM) Parameter Store can be used to manage configuration values for Lambda functions. However, they serve different purposes and have distinct capabilities when it comes to security, scalability, and best practices.
Key-value pairs set directly in the Lambda configuration
Available at runtime via
process.envin Node.js oros.environin PythonSupports encryption using AWS KMS for sensitive data
Limited to 4 KB in total size per function
Ideal for non-sensitive, short-lived, environment-specific settings
Centralized service for managing configuration data and secrets
Supports both plain-text and encrypted (SecureString) parameters
Accessible via AWS SDK (e.g., Boto3, AWS SDK for JS)
Allows versioning, auditing, and fine-grained access control
Better suited for storing shared, sensitive, or dynamic values