Connect to ElastiCache cluster from AWS Lambda function

Question

Is it possible to connect from an AWS Lambda function to a Redis ElastiCache cluster?

I can't figure out if it's a configuration problem or it's simply not possible.

PS: I made a test from an EC2 instance and I can connect to the Redis node. Also the Lambda function and the Redis node are in the same region.

---

UPDATE (09 Oct 2015):

Amazon announced VPC for AWS Lambda functions. Details here

This means we can now access any resource in AWS behind VPC security group, including ElastiCache and RDS machines.

UPDATE (11 Feb 2016): Amazon launched VPC for AWS Lambda.

https://aws.amazon.com/about-aws/whats-new/2016/02/access-resources-within-a-vpc-using-aws-lambda/

Answer 1

As of Feb 2016, AWS allows using lambda functions to connect to Elasticache. Refer to Access Resources within a VPC using AWS Lambda. Here is a link how it works - Tutorial: Configuring a Lambda Function to Access Amazon ElastiCache in an Amazon VPC

Answer 2

Setting up an HTTP Proxy or iptables wouldn't work for the following reasons:

Redis calls are not HTTP and will not be handled by HTTP proxies. iptables (or any port forwarding for that matter) will either won't accept a domain name as destination or is highly inefficient due to DNS resolution required every time.

The best and convenient method is to install twemproxy in an EC2 machine and route your requests through it. As a bonus, you suddenly have deployed a fantastic sharding strategy as well.