Can not access S3 via VPC endpoint in Lambda

Question

I have a Lambda function in my VPC, and I want to access S3 bucket.

I have set S3 VPC endpoint correctly I think,

because I created an EC2 instance in the sa

Answer 1

In addition to all said above, it is also possible that VPC Endpoint policy can be prohibitive and not allowing traffic to/from S3 through. Make sure you allow traffic through endpoint by using "Full access" policy.

Edit: here's related bit of documentation:

Your policy must contain a Principal element. For gateway endpoints only, you cannot limit the principal to a specific IAM role or user. Specify "*" to grant access to all IAM roles and users. Additionally, for gateway endpoints only, if you specify the principal in the format "AWS":"AWS-account-ID" or "AWS":"arn:aws:iam::AWS-account-ID:root", access is granted to the AWS account root user only, and not all IAM users and roles for the account.

So for S3 endpoints to work you need to specify '*' as a principal in general case