Gatekeeper

Link McKinneyFebruary 20, 2025About 1 min

Context and Problem

Applications need to restrict access to resources and enforce security policies at the boundary.

Unauthorized access to sensitive resources.
Difficulty in enforcing uniform security policies across services.
Managing authentication and authorization at multiple layers increases complexity.
Need for rate limiting and bot mitigation.

Solution

The Gatekeeper pattern acts as a security layer that validates access before requests reach application resources.

Deploy a security gateway in front of protected resources.
Implement authentication and authorization mechanisms.
Enforce rate limiting and request validation.
Monitor and log access attempts for security analysis.
Integrate with identity providers for access control.

Benefits

Centralized security: Provides a unified access control mechanism.
Protection: Prevents unauthorized access and mitigates attacks.
Scalability: Offloads security concerns from application services.
Logging and monitoring: Enhances security visibility.

Trade-offs

Performance impact: Security checks may introduce latency.
Complexity: Requires management and integration with authentication systems.
Single point of enforcement: If misconfigured, can block legitimate traffic.

Issues and Considerations

Rate limiting thresholds: Defining optimal limits to balance security and usability.
Authentication overhead: Managing secure and efficient authentication mechanisms.
Logging sensitivity: Ensuring logs do not expose sensitive data.

When to Use This Pattern

When protecting APIs and services from unauthorized access.
When enforcing uniform security policies across applications.
When needing centralized access control.

Example Implementation

class Gatekeeper {
  constructor(private protectedService: ProtectedService) {}

  async handleRequest(request: Request): Promise<Response> {
    try {
      // 1. Authentication
      const token = this.extractToken(request);
      const isAuthenticated = await this.authenticate(token);
      if (!isAuthenticated) {
        return new Response(401, "Unauthorized");
      }

      // 2. Request Validation
      if (!this.validateRequest(request)) {
        return new Response(400, "Invalid Request");
      }

      // 3. Authorization
      if (!this.authorize(request)) {
        return new Response(403, "Forbidden");
      }

      // 4. Sanitization
      const sanitizedRequest = this.sanitizeRequest(request);

      // 5. Forward to Protected Service
      const response = await this.protectedService.process(sanitizedRequest);

      // 6. Audit Logging
      await this.auditLog(request, response);

      return response;
    } catch (error) {
      // 7. Error Handling
      return new Response(500, "Internal Server Error");
    }
  }
}