Connect Lambda function to VPC

• AWS Lamba is a public service which runs within a region. Therefore it can not connect to resources hosted within VPC.

• In some cases you will need to connect your function to VPC to access private resurces ( like database server) during execution.

What do you need to setup Lamba access to VPC ?

• Lambda function needs to be configured with below
  • Private subbet ID
  • Security Group ID
• Lambda function’s execution role must have following permissions:
  • ec2:CreateNetworkInterface
  • ec2:DescribeNetworkInterfaces
  • ec2:DeleteNetworkInterface
  • All above permissions are included in AWSLambdaVPCAccessExecutionRole managed policy.
• Lambda uses above information to setup an Elastic Network Interface (ENI), using avaiable IP from your private subnet.
• Note that Lambda will loose internet connectivity as soon as ENI is setup. You will need NAT Gateway for internet access

How does it look like in a diagram ?

How do you connect Lambda function to VPC ?

Create a Test VPC

Create a Private Subnet

Create a Public Subnet

Create a “Hellow World” Lambda function

Go to configuration and VPC , Setup VPC, Subnet and Security Group.