Introduction
As AWS environments grow, teams often create internal applications that multiple groups depend on. For example, an internal employee registry may start small but quickly become a shared service across teams.
From a general AWS architect’s perspective, the challenge is not building the application itself. Instead, the real work lies in providing secure, private access while keeping the design simple and observable. In this article, we walk through a practical AWS architecture pattern that solves this problem without adding unnecessary complexity.
The Architecture Scenario
Consider an internal employee registry application running as containerized microservices in a single AWS Region. The application runs inside its own VPC and serves other internal teams.
Meanwhile, those teams operate workloads in separate VPCs. They need reliable access to the registry; however, security teams also set clear expectations:
- Traffic must stay private within AWS
- Network access failures must be visible
- Source IP addresses must be traceable
As a result, the architecture must balance connectivity, security, and operational clarity.
Choosing the Right AWS Networking Approach
When designing private VPC-to-VPC connectivity, architects usually evaluate multiple options. However, in a single-region setup, VPC Peering often stands out as the most practical choice.
VPC Peering allows VPCs to communicate using private IP addresses over the AWS backbone. Therefore, traffic never touches the public internet. In addition, it offers low latency and requires very little ongoing maintenance.
In this pattern, each team VPC establishes a peering connection with the central application VPC. After that, route tables explicitly allow traffic between the networks. As a result, teams gain secure access without introducing extra networking layers.
Improving Visibility with VPC Flow Logs
Private connectivity alone does not solve visibility concerns. For that reason, architects usually add logging early in the design.
By enabling VPC Flow Logs, teams can record network traffic decisions at the VPC level. More importantly, by capturing rejected traffic, they can quickly understand why certain connections fail.
These logs include:
- Source IP addresses
- Destination IP addresses
- The action taken (ACCEPT or REJECT)
Flow logs are then sent to Amazon CloudWatch Logs, which makes searching and analysis straightforward.
Centralizing Security Monitoring
To keep responsibilities clearly separated, architects often centralize security monitoring in a dedicated account. Using CloudWatch Logs subscription filters, flow logs can stream automatically to the security team’s account.
Because of this setup, security teams can:
- Review denied traffic across all VPCs
- Set alerts for repeated failures
- Investigate issues without accessing application resources
As a result, both DevOps and security teams can work independently while sharing the same visibility.
Why This Architecture Pattern Works
This pattern works well because it follows a few core AWS design principles:
- It keeps traffic private and inside AWS
- It relies on native AWS services
- It avoids complex networking components
- It scales easily as new VPCs are added
Most importantly, it remains easy to explain, operate, and troubleshoot.
Conclusion
Secure private access to internal applications on AWS does not require complex networking designs. In many cases, VPC Peering combined with VPC Flow Logs provides everything teams need.
From a general AWS architect’s point of view, this pattern offers a clean balance between security, simplicity, and visibility. As environments grow, it continues to scale without forcing teams to rethink their core network design.