Build an enterprise API management solution using Amazon API Gateway

Enterprises face many challenges when they build and manage application programming interfaces (APIs). These challenges include security controls, version management, traffic control, and usage analytics. As digital businesses expand, a mature API management (APIM) solution is crucial for ensuring scalability, security, and operational efficiency.

This blog post shows how you can use Amazon API Gateway—along with AWS Lambda, Amazon DynamoDB, and other AWS services—to create a comprehensive and customizable APIM solution. This solution addresses the complex requirements of large enterprises managing APIs at scale.

Core features of APIM

API Management (APIM) centralizes the management and publishing of APIs for the entire enterprise, acting as a hub between clients, applications, and administrators on one side, and internal services, external systems, and large language models (LLMs) on the other, as shown in the following figure.

The key features of APIM include:

• Security and governance
  • Authentication, authorization, rate limiting, and security policy enforcement.
  • Helps ensure APIs meet organizational or industry standards.
• Monitoring and logging
  • Provides monitoring, alarms, and logging to track API performance and troubleshoot issues quickly.
• Customization and transformation
  • Offers protocol and field transformations, plus orchestration and aggregation.
  • Makes it easier to integrate with different systems and meet various client needs.
• API lifecycle management
  • Publishing, rollback, version control, and documentation.
  • Streamlines development and maintenance throughout the API lifecycle.
• Developer and business tools
  • Portals for developers, business owners, and administrators to manage documentation, billing, and analytics.
• Integration with LLMs
  • Specialized adapters, proxy configurations, and switching to integrate AI models seamlessly.
• Flexible deployment options
  • Canary releases, pipeline automation, and other advanced release strategies.
  • Helps ensure stable, controlled API updates.

Unified management of multiple API gateways

API Gateway enforces resource limits of 300 resources per gateway, with a hard limit of 600. For enterprises that require more resources, managing multiple gateways individually can be time-consuming and error prone. APIM simplifies this by integrating API Gateway, Lambda, and DynamoDB; creating a centralized platform for managing APIs across multiple gateways. This integration streamlines the process, making it easier to scale and maintain APIs.

API lifecycle management

Managing API versions, publishing updates, and maintaining documentation often requires separate tools and manual processes, leading to inefficiencies. APIM centralizes these tasks in one portal, offering version control, publishing workflows, and rollback options. This streamlines the API lifecycle, ensuring consistency and reducing the chances for errors.

Enhanced security

Enterprises often need to implement different authentication strategies for various clients. These configurations typically require custom Lambda logic and database lookups, adding complexity and cost. APIM introduces configurable security policies that allow client-specific authentication without the need for additional custom code, reducing both complexity and operational overhead.

Customization and transformation

Enterprises frequently handle diverse client requests that involve different formats and protocols. Traditional API management approaches might struggle to support such variations. APIM allows for seamless protocol and field transformations, enabling integrations that meet a wide range of client requirements without additional development effort.

Developer portal

Developers need clear documentation, easy testing environments, and efficient API key management to work effectively. Traditional systems often lack these features, slowing down adoption. APIM provides a developer portal that consolidates API documentation, offers sandbox environments for testing, and simplifies API key management, reducing onboarding time and improving the developer experience.

Logging and monitoring

Log management is key to maintaining API performance, diagnosing issues, and gaining insights into usage. APIM uses API Gateway custom access logging, allowing teams to define logs based on business needs; whether creating separate CloudWatch metrics for each API path or exporting data to external platforms like ELK or Grafana.

Architecture overview

The APIM architecture, shown in the following figure, includes a management state (represented by numbers) and a runtime state (represented by letters). Both parts use a serverless paradigm.

Management state

The management state includes the following elements:

1. Administrator portal access: Administrators access the APIM solution through a secured web portal.
2. API Requests to APIM Lambda: Requests from the administrator’s API go through API Gateway, which then invokes the APIM Lambda function. This function handles logic related to configuration changes and other administrative actions.

In the following example, we show you how the APIM Lambda function dynamically applies different middleware based on the route configuration. This approach allows for flexible handling of authentication, client access restrictions, and request/response transformations. Here’s a quick breakdown of the key elements:

// If the route requires OIDC (OpenID Connect) authentication,
// add the OIDC authentication middleware to the route.
if route.Auth == "OIDC" {
    r.Use(middleware.OidcAuthenticator)
}
// If the route configuration specifies a list of allowed clients
// and the list is not empty, add a middleware to restrict access
// to only the specified clients.
if route.Allow.Clients != nil && len(route.Allow.Clients) != 0 {
    r.Use(middleware.AllowClients(route.Allow.Clients, cfg.Clients))
}
// Remove specific headers injected by the API Gateway
// to reduce exposure of internal details to downstream systems.
r.Use(middleware.RemoveGatewayHeaders)

// Add additional middleware for handling outbound logic.
// This could include retries, logging, or other outbound-specific functionality.
r.Use(outboundMiddlewares)
// Dynamically constructs and applies a chain of middlewares 
// based on the outbound configuration associated with the current request.
func outboundMiddlewares(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        // Retrieve the outbound configuration from the request context.
        outbound, _ := r.Context().Value(selectedOutboundContext).(config.Outbound)

        // Initialize a slice to store the middlewares to be applied.
        middlewares := []func(http.Handler) http.Handler{}

        // Middleware to rewrite the HTTP request based on the outbound configuration.
        middlewares = append(middlewares, middleware.ProxyRequestRewrite(&outbound))

        // Add a middleware for mapping request data if specified in the outbound configuration.
        if len(outbound.Convert.Request) != 0 {
            middlewares = append(middlewares, middleware.RequestDataMapping(outbound.Convert.Request))
        }

        // Middleware to log the outbound response for monitoring or debugging purposes.
        middlewares = append(middlewares, middleware.OutboundResponseLog)

        // Add a middleware for mapping response data if specified in the outbound configuration.
        if len(outbound.Convert.Response) != 0 {
            middlewares = append(middlewares, middleware.ResponseDataMapping(outbound.Convert.Response))
        }

        // Add a middleware for modifying the response if a modification function is defined.
        if outbound.ModifyResponse != "" {
            f, ok := system.MODIFY[outbound.ModifyResponse]
            if ok {
                middlewares = append(middlewares, f())
            }
        }

        // Chain the constructed middlewares together and apply them to the request.
        chain := chi.Chain(middlewares...)
        chain.Handler(next).ServeHTTP(w, r)
    })
}

By using a middleware chain, you can customize how each request and response is processed on a per-route basis. This architecture not only keeps your code organized but also makes the API Gateway-integrated Lambda function far more adaptable to changing requirements. You can add or remove configurations from APIM portal as new use cases emerge—such as data transformations, custom logging, or additional security checks—without rewriting core logic.

3. Configuration management: Administrators set up server-side and client-side settings, such as API Gateway parameters, authentication requirements, transformations, and more.
4. Persistence:  DynamoDB stores these configurations, providing persistent data storage and auditing capabilities.
5. Asynchronous resource provisioning: After administrators save configurations and release them from the APIM portal, APIM creates or updates AWS resources—such as API Gateway, Lambda functions, and AWS Identity and Access Management (IAM). Lambda runs these updates in the background, so administrators can continue working uninterrupted.

Runtime state

The runtime state includes the following elements:

A. Client request: Clients send requests to the APIM endpoint.

B. Routing to the correct gateway: APIM uses the URI prefix in the API mappings associated with custom domain names to route requests to the appropriate API gateway, as shown in the following figure. Each mapping defines a specific API, stage, and an optional path. When a request arrives, APIM checks the path and directs the request to the correct stage and API if it matches. Unmatched requests default to the mapping with no path defined.

C. APIM core processing: A Lambda function (APIM CORE) uses DynamoDB configurations to handle authentication, authorization, protocol conversion, field transformation, and routing.

D. Downstream service call: APIM forwards each request to the configured internal or external endpoint.

E. Logging and monitoring: API Gateway access logs and custom logs track requests in detail.

F. Alarm: Metrics and alarms detect anomalies and notify stakeholders. Use Amazon CloudWatch or self-hosted solutions such as ELK to enable real-time monitoring and alerting.

Conclusion

In this post, we’ve demonstrated how to build an enterprise API management (APIM) solution using Amazon API Gateway, AWS Lambda, Amazon DynamoDB, and other AWS services. We’ve also shown how APIM centralizes critical features—such as version management, security policies, and request/response transformations—to accommodate large-scale enterprise requirements.

You can use the APIM portal to store and manage configurations in DynamoDB, dynamically applying these settings to multiple API gateways without rewriting code. This approach ensures consistent governance across diverse client types and business scenarios, helping to keep APIs both secure and flexible.

Finally, you’ve seen how the APIM architecture unifies the management state and runtime state, streamlines administrative tasks, and provides end-to-end monitoring and alerting. By adopting these best practices, your enterprise can establish a robust, scalable, and secure API management foundation, all within a serverless paradigm.

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