AWS Lambda times out connecting to RedShift

The timeout is probably because your lambda in VPC cannot access Internet in order to connect to your cluster(you seem to be using the public hostname to connect). Your connection options depend on your cluster configuration. Since both your lambda function and cluster are in the same VPC, you should use the private IP of your cluster to connect to it. In your case, I think simply using the private IP should solve your problem.

Depending on whether your cluster is publicly accessible, there are some points to keep in mind.

• If your cluster is configured to NOT be publicly accessible, you can use the private IP to connect to the cluster from your lambda running in a VPC and it should work.

• If you have a publicly accessible cluster in a VPC, and you want to connect to it by using the private IP address from within the VPC, make sure the following VPC parameters to true/yes:

  • DNS resolution
  • DNS hostnames

The steps to verify/change these settings are given here.

If you do not set these parameters to true, connections from within VPC will resolve to the EIP instead of the private IP and your lambda won't be able to connect without having Internet access(which will need a NAT gateway or a NAT instance).

Also, an important note from the documentation here.

If you have an existing publicly accessible cluster in a VPC, connections from within the VPC will continue to use the EIP to connect to the cluster even with those parameters set until you resize the cluster. Any new clusters will follow the new behavior of using the private IP address when connecting to the publicly accessible cluster from within the same VPC.