Save AWS Costs: Use VPC Endpoints Instead of NAT Gateways#

AWS NAT Gateways are convenient but expensive, especially when handling high outbound traffic. If your workloads need to connect to AWS services like S3, DynamoDB, or Secrets Manager, using VPC Endpoints can drastically reduce costs while improving security and performance.

Why NAT Gateways Are Costly#

NAT Gateways charge you for hourly usage and data transfer. At $0.045 per GB (region-dependent), costs quickly escalate for data-intensive applications. VPC Endpoints, on the other hand, offer a flat hourly rate with no data transfer fees for AWS services.

How to Identify NAT Gateway Traffic to AWS Services#

Before setting up VPC Endpoints, it’s essential to analyze NAT Gateway traffic to determine which AWS services your instances access. Follow these steps:

1. Enable VPC Flow Logs:

   • Navigate to VPC Console → Flow Logs → Create Flow Log.

   • Select your VPC and log destination (CloudWatch or S3).

2. Analyze Flow Logs:

   • Use Athena or CloudWatch Insights to filter traffic logs and identify AWS service endpoints being accessed.

   • Example query in CloudWatch Insights:

     filter dstAddr like 'amazonaws.com'
     | stats count(*) by dstAddr

     plaintext

3. Check NAT Gateway Metrics:

   • Navigate to CloudWatch → NAT Gateway Metrics.

   • Monitor BytesOutToDestination to analyze traffic volume per AWS service.

When to Use VPC Endpoints#

Use VPC Endpoints if your EC2 instances or services:

• Frequently access S3, DynamoDB, or other AWS services.

• Have high outbound traffic that doesn’t require internet access.

• Need better security by avoiding internet-based traffic.

Setting Up a VPC Endpoint#

Follow these steps to replace your NAT Gateway with a VPC Endpoint:

1. Create a VPC Endpoint#

1. Navigate to AWS Console → VPC → Endpoints.

2. Click Create Endpoint.

3. Select the AWS service (e.g., S3, DynamoDB) based on NAT traffic analysis.

4. Choose the VPC and Subnet where your instances are running.

5. Select the private route table to ensure traffic stays within AWS.

6. Click Create Endpoint.

2. Update Security Groups & Routing#

• Allow traffic from your instances to the VPC Endpoint in security groups.

• Update Route Tables to ensure traffic is directed to the VPC Endpoint instead of the NAT Gateway.

3. Remove NAT Gateway (If No Longer Needed)#

If all your AWS service traffic is routed through VPC Endpoints, you can remove the NAT Gateway to stop hourly charges:

aws ec2 delete-nat-gateway --nat-gateway-id nat-0abcd1234efgh5678

Cost Savings Breakdown#

Conclusion#

Switching to VPC Endpoints can save hundreds to thousands per month, depending on your workload. Start by analyzing NAT Gateway traffic, setting up the right VPC Endpoints, and eliminating unnecessary NAT costs.

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