text: Using IAM roles to describe a Lambda function’s permissions, decouples security conﬁguration 
  
  from the code. This helps reduce the complexity of a lambda function, making it easier to maintain. 
  
  A Lambda function’s resource and execution policy should be granted the minimum required 
  
  permissions for the function to perform it’s task eﬀectively. This is sometimes referred to as the 
  
  rule of least privilege. As you develop a Lambda function, you expand the scope of this policy to 
  
  allow access to other resources as required. 