This IAM policy allows Lambda functions to be executed within a VPC (Virtual Private Cloud). It grants permissions to create, delete, and describe network interfaces, which are necessary for Lambda functions to connect to resources within the VPC.

IAM Policy for Lambda VPC Execution

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:CreateNetworkInterface",
                "ec2:DeleteNetworkInterface",
                "ec2:DescribeNetworkInterfaces"
            ],
            "Resource": "*"
        }
    ]
}

Explanation

This policy includes the following:

• Version: Specifies the version of the policy language.
• Statement: Contains an array of individual statements.
• Effect: Determines whether the statement results in an allow or an deny.
• Action: Lists the specific actions that are allowed. In this case, creating, deleting, and describing network interfaces.
• Resource: Specifies the resources that the actions apply to. "*" indicates all resources.

Use Cases

This policy is essential when your Lambda function needs to access resources within a VPC, such as databases, caches, or other internal services. By granting these permissions, the Lambda function can create and manage the necessary network interfaces to establish a connection.

Best Practices

While this policy grants necessary permissions, it's crucial to follow security best practices:

• Least Privilege: Consider narrowing down the Resource to specific VPCs or network interfaces if possible.
• Regular Audits: Regularly review and audit your IAM policies to ensure they are still appropriate and secure.

Additional Resources

• AWS Lambda VPC Configuration Documentation
• AWS IAM Policies Overview
• Amazon VPC