AWS Lambda:The Provided Execution Role Does Not Have Permissions To Call DescribeNetworkInterfaces On EC2

Answer :

This error is common if you try to deploy a Lambda in a VPC without giving it the required network interface related permissions ec2:DescribeNetworkInterfaces, ec2:CreateNetworkInterface, and ec2:DeleteNetworkInterface (see AWS Forum).

For example, this a policy that allows to deploy a Lambda into a VPC:

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

If you are using terraform, just add:

resource "aws_iam_role_policy_attachment" "AWSLambdaVPCAccessExecutionRole" {     role       = aws_iam_role.lambda.name     policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole" } 

via AWS CLI using a Managed Policy

• To grant my Lambda necessary permissions to dig in to a VPC where a production RDS db lives.
• As mentioned by @portatlas above, the AWSLambdaVPCAccessExecutionRole managed policy fits like a glove (and we all know IAM Managed Policies are an AWS-recommended best-practice).
• This is for Lambda's with a service role already attached.

1. Get Lambda Service Role

• Piping aws lambda get-function-configuration output in to a grep for Role (probably a cleaner/leaner/meaner way to do this)

  aws lambda get-function-configuration \     --function-name <<your function name or ARN here>> \     | grep "Role" 

• return

  "Role": "arn:aws:iam::000000000000:role/service-role/your-service-role-name", 

• Take the value after the Role ARN's last slash your-service-role-name to #2

2. Attach Managed Policy AWSLambdaVPCAccessExecutionRole to Service Role

aws iam attach-role-policy \     --role-name your-service-role-name \     --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole