AWS Lambda reserves certain environment variable names for its internal operations and runtime management. These reserved variables, such as
'_HANDLER', '_X_AMZN_TRACE_ID', 'AWS_REGION', and others, are automatically set by the Lambda service and contain critical information about the
function’s execution context. When application code overrides these reserved environment variables by assigning new values to them, it can disrupt the
Lambda runtime’s ability to function correctly. The Lambda service relies on these variables to manage function execution, implement tracing, handle
authentication, and maintain proper communication with other AWS services.
What is the potential impact?
Overriding reserved environment variables can lead to unpredictable Lambda function behavior, runtime failures, broken tracing and monitoring
capabilities, authentication issues with AWS services, and difficulty in debugging production problems. This can result in service outages and
degraded system reliability.
