How to fix “The provided execution role does not have permissions to call CreateNetworkInterface on EC2”

Amazon Web Services (AWS) offers a variety of services for developers and businesses, including the Elastic Compute Cloud (EC2), which provides scalable virtual machines. However, as with any cloud service, you may encounter some issues while working with it. One common error that AWS users face is "The provided execution role does not have permissions to call CreateNetworkInterface on EC2." In this blog post, we will discuss the root cause of this error and provide a step-by-step guide to fixing it on codedamn.

Understanding the Execution Role

Before diving into the solution, let's discuss the execution role in AWS. An execution role is an AWS Identity and Access Management (IAM) role that grants permissions to an AWS service to access specific resources. It allows you to define which actions the service can perform on your behalf.

In the context of EC2, the execution role is used to grant permissions for AWS Lambda functions to access other AWS resources. For instance, if a Lambda function needs to access an Amazon S3 bucket or interact with an Amazon RDS database, you need to specify an execution role with the required permissions.

The Root Cause of the Error

The error "The provided execution role does not have permissions to call CreateNetworkInterface on EC2" occurs when the execution role associated with your Lambda function does not have the necessary permissions to create a network interface on EC2. This is required when you have configured your Lambda function to access resources within a Virtual Private Cloud (VPC).

To fix this error, you need to update the execution role's policy to include the necessary permissions.

Fixing the Error

The following steps will guide you through the process of fixing the error:

Step 1: Identifying the Execution Role

First, you need to identify the execution role associated with your Lambda function. You can find this information in the AWS Management Console:

1. Log in to the AWS Management Console.
2. Navigate to the Lambda service.
3. Click on the name of the Lambda function that is causing the error.
4. In the "Function overview" section, locate the "Execution role" field. Note down the role name or the Amazon Resource Name (ARN) for the role.

Step 2: Updating the Execution Role Policy

Once you have identified the execution role, you need to update its policy to include the necessary permissions. Follow these steps to update the role policy:

1. Navigate to the IAM service in the AWS Management Console.
2. Click on "Roles" in the left-hand menu.
3. Find the execution role you identified in Step 1 and click on its name.
4. Click on the "Add inline policy" button.
5. Select the "JSON" tab and replace the existing policy with the following JSON policy document:

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

This policy grants the necessary permissions to create, describe, and delete network interfaces on EC2.

6. Click on "Review policy" and then provide a name for the policy, such as "LambdaEC2NetworkPermissions".
7. Click on "Create policy" to save the changes.

Step 3: Verifying the Changes

After updating the execution role policy, you should verify that the error is resolved:

1. Go back to the Lambda function in the AWS Management Console.
2. Click on the "Test" button to trigger the Lambda function.
3. Check the "Function logs" section for any error messages. If the changes were successful, you should no longer see the "CreateNetworkInterface" error.

FAQ

Q: How can I restrict the permissions to specific resources?

A: In the JSON policy document, you can replace the "Resource": "*" line with a more specific resource ARN. For example, to restrict the permissions to a specific VPC, you can use "Resource": "arn:aws:ec2:region:account-id:vpc/vpc-id".

Q: Can I use AWS CLI to update the execution role policy?

A: Yes, you can use the AWS Command Line Interface (CLI) to update the policy. First, create a JSON file with the policy document, then use the aws iam put-role-policy command to update the role. Refer to the official AWS CLI documentation for more details.

Q: What other permissions might be required for Lambda functions in a VPC?

A: Depending on your use case, you may need to grant additional permissions to your Lambda function, such as read/write access to Amazon S3, access to Amazon RDS databases, or access to other AWS services. Always follow the principle of least privilege when configuring permissions to ensure your resources are secure.

In conclusion, fixing the "The provided execution role does not have permissions to call CreateNetworkInterface on EC2" error requires updating the execution role policy to include the necessary permissions. By following the steps outlined in this blog post, you can resolve the issue and continue working with your Lambda functions on codedamn. Remember to always verify the changes and ensure your Lambda function has the appropriate permissions to access the required resources.