How do IAM policies work with AWS Lambda functions?

How do IAM policies work with AWS Lambda functions?

IAM policies are used to define permissions for AWS Lambda functions, controlling what resources they can access.

Can you give me an example of an IAM policy for a Lambda function?

Sure! Here's a simple policy that allows a Lambda function to read from an S3 bucket:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::your-bucket-name/*"
    }
  ]
}

What happens if I don't attach an IAM policy to my Lambda function?

If no IAM policy is attached, the Lambda function won't have permissions to access any AWS resources, leading to access denied errors.

How can I test if my IAM policy is working correctly?

You can test your IAM policy by invoking the Lambda function and checking the logs for any permission errors in CloudWatch.