New – Access Resources in a VPC from Your Lambda Functions

A few months ago I announced that you would soon be able to access resources in a VPC from your AWS Lambda functions. I am happy to announce that this much-wanted feature is now available and that you can start using it today!

Your Lambda functions can now access Amazon Redshift data warehouses, Amazon ElastiCache clusters, Amazon Relational Database Service (Amazon RDS) instances, and service endpoints that are accessible only from within a particular VPC. In order to do this, you simply select one of your VPCs and identify the relevant subnets and security groups. Lambda uses this information to set up elastic network interfaces (ENIs) and private IP addresses (drawn from the subnet or subnets that you specified) so that your Lambda function has access to resources in the VPC.

Accessing Resources in a VPC
You can set this up when you create a new function. You can also update an existing function so that it has VPC access.  You can configure this feature from the Lambda Console or from the CLI.  Here’s how you set it up from the Console:

That’s all you need to do! Be sure to read Configuring a Lambda Function to Access Resources in an Amazon VPC in the Lambda documentation if you have any questions.

Things to Know
Here are a couple of things that you should know about this new feature:

ENI & IP Address Resources – Because Lambda automatically scales based on the number of events that is needs to process, your VPC must have an adequate supply of free IP addresses on the designated subnets.

Internet Access – As soon as you enable this functionality for a particular function, the function no longer has access to the Internet by default. If your function requires this type of access, you will need to set up a Managed NAT Gateway in your VPC (see New – Managed NAT (Network Address Translation) Gateway for AWS for more information) or run your own NAT (see NAT Instances).

Security Groups – The security groups that you choose for a function will control the function’s access to the resources in the subnets and on the Internet.

S3 Endpoints – You can also use this feature to access S3 endpoints within a VPC (consult New – VPC Endpoint for Amazon S3 to learn more).

Webinar – To learn more about this new feature, join our upcoming webinar, Essentials: Introducing AWS VPC Support for AWS Lambda.

— Jeff;