Fundamentals: What is an API Gateway?

When talking about managing web applications and the services they provide, the term “API gateway” is often thrown around, but what does it mean? In order to unpack how a gateway functions, we first need to understand what an API is.

Application Programming Interface

API stands for “application programming interface”, and it’s a way for programs to communicate with each other. Conceptualizing what an API does can be difficult because it’s a program that functions principally behind the scenes, interacting between client and server to deliver pieces of information to users without opening the door to all the moving parts. While APIs can function as connectors to web services built in-house, where APIs really begin to shine is in their ability to provide a public, paid service to other companies, enabling API consumers to quickly construct new applications with far less custom development.

The ability to leverage APIs to draw information and features from other sources means developers don’t have to make an application from scratch. Using APIs allows companies to integrate with other service providers, can make development more feasible, and can create new revenue streams. From using payment APIs to carry out transactions, to accessing address database APIs to auto-fill and verify contact information, developers can tap into thousands of ready-made services to build their applications and fill in the blanks. This allows businesses to get to market faster, relying on the engineering effort other companies have already done, and for some companies, these APIs can be the key to their success.

You can imagine that with so much modern software relying on these application programming interfaces, the demand on APIs can be strenuous. If you are an API provider, you may be feeling the weight on your infrastructure as thousands of others depend on the functions and information you provide. Handling this level of demand can be challenging for your APIs, and ensuring their high availability is critical.

API Gateways

A gateway can make handling these APIs simple. An API Gateways is a management tool for application programming interfaces, and is installed on a server in front of your APIs. Clients connect to the gateway–instead of each API individually–and are routed to the correct API service corresponding to their request. The gateway acts as a one-stop shop for APIs, providing access at a single IP address, proxying the connections, and managing the scale of requests that pass through it.

Think of an API gateway as a proxy (we explore the role of a reverse proxy in our blog post, “Fundamentals: High Availability and the Role of a Reverse Proxy”). Like a reverse proxy, the API gateway functions to both route and manage traffic to APIs. It’s a tool to ensure that requests reach the right destination and that they’re carried out completely, all while managing the system load the APIs face.

Building a gateway capable of carrying out these functions for your APIs, along with being secure, reliable, and observable, requires a sophisticated load balancing solution that can stand up to the rigors of a microservices architecture. Products like HAProxy Enterprise and HAProxy Enterprise Kubernetes Ingress Controller are the perfect choice for such a task, capable of being deployed in the cloud, on-premises, or as part of a Kubernetes infrastructure.

The versatility of the HAProxy product suite offers several benefits as an API gateway, including:

  • flexible load balancing to optimize the performance and reliability of your APIs by distributing requests evenly across a pool of servers;

  • customizable routing to consolidate APIs behind a single address, simplifying discovery and use of their data, enabling easy maintenance;

  • better security by narrowing the attack surface available to hackers with all traffic flowing through a single entry point; and

  • observable and accelerated APIs with unrivaled insight on system logs and metrics, as well as fine-grained tuning options to optimize for the traffic type.

Learn more about API gateways and read our ebook on how HAProxy can be the right tool for managing your application programming interfaces.

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