Security & IAM for Lambda

Introduction

AWS Lambda allows you to run code without provisioning or managing servers. However, securing your Lambda functions is essential to protect your data and resources. This lesson covers key concepts related to Identity and Access Management (IAM) for AWS Lambda.

IAM Overview

AWS IAM (Identity and Access Management) is a web service that helps you securely control access to AWS services and resources for your users. IAM allows you to manage permissions for your Lambda functions.

• Users: Individuals who need access to AWS resources.
• Groups: Collections of users with similar permissions.
• Roles: Defined permissions that can be assumed by AWS services or users.
• Policies: Documents that define permissions for actions on AWS resources.

Creating IAM Roles for Lambda

When you create a Lambda function, you must assign an IAM role that grants the function permission to use other AWS services.

aws iam create-role --role-name MyLambdaRole --assume-role-policy-document file://trust-policy.json
            

In the above command, the trust-policy.json file specifies which services can assume the role. Here is an example of a trust policy for a Lambda function:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}
            

Managing Permissions

After creating a role, you need to attach policies that define permissions. For example, granting access to read from a DynamoDB table:

aws iam attach-role-policy --role-name MyLambdaRole --policy-arn arn:aws:iam::aws:policy/AmazonDynamoDBReadOnlyAccess
            

You can create custom policies as well, using JSON. Here is an example of a policy granting access to specific DynamoDB tables:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "dynamodb:GetItem",
      "Resource": "arn:aws:dynamodb:us-west-2:123456789012:table/MyTable"
    }
  ]
}
            

Best Practices

• Use the principle of least privilege: Grant only the permissions necessary for the function.
• Regularly review IAM roles and policies to ensure they are up-to-date.
• Utilize AWS CloudTrail to monitor API calls and changes to your IAM policies.
• Use environment variables for sensitive information instead of hardcoding them in your code.

FAQ

Flowchart of IAM Role Creation

graph TD;
    A[Start] --> B[Define Trust Policy]
    B --> C[Create IAM Role]
    C --> D[Attach Policies]
    D --> E[Assign Role to Lambda]
    E --> F[End]