MongoDB Atlas VPC peering

Question

Hi AWS,

I am deploying a web application backend for testing purpose on Amazon EC2 instance. The instance is inside a VPC. The EC2 and VPC are in us-east-2 Ohio region and the MongoDB Atlas cluster is in us-east-1 N. Virginia region.

The Atlas CIDR (VPC region) is same as Amazon VPC i.e. us-east-2 Ohio. The VPC CIDR is 172.31.0.0/20 and the Atlas VPC CIDR is 192.168.248.0/21.

When I am checking the logs on the EC2 instance I am seeing the error:
**ERROR [MongooseModule] Unable to connect to the database. Retrying (1)...**

The problem is I can't enable the **Access from Anywhere** option 0.0.0.0/0 assuming if I need to perform the same in production.

Please suggest how to fix this.

Answer

If you are doing VPC peering, you can refer to the security group of the peering destination as shown in the following document.  
So try to put a setting in the Mongo DB security group to allow the EC2 security group.  
https://docs.aws.amazon.com/vpc/latest/peering/vpc-peering-security-groups.html

MongoDB Atlas VPC peering

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