Unable to connect Lambda in private subnet to S3 through VPCE Endpoint

Question

I've been trying to connect to S3 bucket from a lambda residing in a private subnet. I did the exact same thing for Ec2 instance and it worked like a charm, I'm not sure why with lambda it's such an issue. My lambda times out after a certain defined interval.

Here's my lambda's VPC configuration

Here's the security group output configuration:

Below are the outbound rules of the subnet associated with lambda

As you can see, I created a VPC endpoint to route my traffic through the VPC but it doesn't work. I'm not sure what am I missing here. Below is the VPC Endpoint configuration.

I've given full access to S3 in policy like this:

{
"Statement": [
    {
        "Action": "*",
        "Effect": "Allow",
        "Resource": "*",
        "Principal": "*"
    }
]

}

When I run my lambda code, I get timeout error as below:

Answer 1

To reproduce your situation, I performed the following steps:

• Created an AWS Lambda function that calls ListBuckets() . Tested it without attaching to a VPC. It worked fine.
• Created a VPC with just a private subnet
• Added an Amazon S3 Endpoint Gateway to the VPC and subnet
• Reconfigured the Lambda function to use the VPC and subnet
• Tested the Lambda function -- it worked fine

I suspect your problem might lie with the Security Group attached to the Lambda function. I left my Outbound rules as "All Traffic 0.0.0.0/0" rather than restricting it. Give that a try and see if it makes things better.

Answer 2

You can access Amazon S3 objects using VPC endpoint only when the S3 objects are in the same Region as the Amazon S3 gateway VPC endpoint . Confirm that your objects and endpoint are in the same Region .