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What is an API Gateway?

What is an API Gateway?

Harold Bell
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Key Takeaways

When deployed, an API gateway is the single-entry point that sits in front of an API to accept API calls and aggregates the requests to the various required services. API Gateways also enforce API security for microservices and prevent unnecessary exposure.

An API gateway acts as a reverse proxy, sitting between a collection of backend services and a client. The gateway accepts client API requests and directs them to the appropriate microservices. In a nutshell, the API gateway accepts API calls and aggregates the requests to the various required services. It serves as a bridge between internally used web unfriendly protocols and web protocols that users understand.

For example, an e-commerce site might use an API gateway to invoke and combine the results from various services. Like combining customers reviews and product info for users to provide a more seamless shopping experience.

At the enterprise level, most APIs are deployed using API gateways. API gateways generally handle typical tasks for various API services across a system, such as rate limiting and user authentication. They can also decrease errors and make coding easier, making mobile application development more efficient.

How does an API gateway work?

The API gateway is the single-entry point that sits in front of an API. It enforces API security for microservices (which can be both internal and external) and defined back-end APIs. The API gateway also ensures high availability and scalability.

An API gateway decouples the backend implementation and the client interface on the server side. It determines which services are needed to respond to client requests. The API gateway receives and responds to client requests by breaking them down into multiple, more manageable tasks. It routes those requests to the appropriate services, and tracking the response produced.

Why use an API gateway?

An API gateway is a critical API management tool. Let’s review just a few of the most notable reasons this is the case.

Prevents unnecessary exposure

An API gateway separates internal microservice APIs and external public APIs, enabling users to change boundaries and add microservices. This in turn lets users gradually adjust and improve microservices without affecting external clients negatively. And by providing a single point of entry for all microservices, it hides versioning and service discovery details from the client.

Enhances microservices security

API gateway microservices are more secure. They have an additional layer of protection from malicious API security attack vectors. Things like XML parser exploits, SQL injection, and denial-of-service (DoS) attacks. This enhanced security is among the most important benefits.

Supports mixed communication protocols

Possible communication protocols may include AMQP or ProtoBuf, or service integration with JSON-RPC, SOAP, or XML-RPC. Although internal microservices may benefit from using different protocols, external-facing APIs typically offer just REST-based or an HTTP-based API. With an API gateway, teams can select the protocols that best suit the internal architecture.

Reduces complexity

Microservices share common issues, and each may require development and implementation time per service. These concerns include access control enforcement, API gateway authorization using tokens (also called API gateway token validation), and rate limiting. An API gateway allows microservices to manage just their own tasks by taking over these code concerns.

Virtualization and mocking

The team can virtualize and mock up services to assist in service integration testing. Or they can validate design requirements because the gateway separates the external API and the microservice APIs.

Challenges of using an API gateway

Despite the list of benefits that API gateways provide, there are a few setbacks that you should be aware of before blindly deploying an API gateway. Here are a few of the key challenges you should consider.

Can increase latency

Since API gateways have multiple layers of functionality, which can cause latency issues when too many requests are coming in at once.

Doesn’t provide complete visibility

It’s likely that your organization manages thousands of APIs. However, for a myriad of reasons, not all of them are routed through an API gateway. Which means you don’t have complete visibility.

Centralization can cause vulnerabilities

For the same reason that API gateways make it easier to connect to microservices by being the single point of contact, they also can become the single point of failure if infiltrated.

API proxy vs API gateway

Both an API gateway and an API proxy allow access to backend services. An API gateway may actually serve as a simple API proxy. But an API proxy cannot replace the more robust range of features of the API gateway. This is particularly true around monitoring and API security.

API gateway vs load balancer

Load balancers smooth out demand across multiple resources. Load balancers are also used in a cloud architecture setting to decouple clients and services.

Horizontally scaled infrastructure clusters are the traditional home of load balancers, where they are used to distribute requests. Inside this type of infrastructure cluster, a single server lacks power sufficient to handle all the demand. This is because systems are replicated across multiple servers.

API gateway can also balance and smooth out network traffic, but not in the same way the load balancer does. A user can configure direct requests to specific resources based on requested endpoints.

However, the API gateway serves its own critical purpose in microservices architectures. It routes each request to the appropriate backend service on-demand. And it allows users to map multiple services to particular HTTP endpoint representations and connect.

API gateway vs API management

Despite being used interchangeably, an API gateway is not the same as API management.

An API gateway is a software that provides a single point of entry for all the traffic coming to an application. It is an intermediary between the backend services and the application or client that needs to access them.

API Management on the other hand, refers to the holistic practice of managing APIs and their associated data, the security, performance, and availability of these APIs. Things like:

  • Creating policies
  • Monitoring API usage
  • Creating developer portals
  • and more.

The key difference to understand is that API gateways are a component of the API management process and provide critical information to management platforms.

API gateways vs microservices

The primary difference between monolithic applications and those that pursue a microservices architecture is that backend services are decoupled from the application and operate independently. For scale this is great, but routing API requests can get a little interesting.

For the reason, the API gateway was created. An API gateway alleviates this routing issue by acting as the single barrier/point-of-contact between the client and the microservices. That way, clients are sending requests to an API gateway versus hundreds of backend services.

Here are some things to consider when trying to remember the different between these two:

  • An API Gateway provides a single entry point for all the APIs in your application
  • Microservices are small, independent, and modular pieces of code
  • Microservices communicate with each other through APIs

Do API gateways offer adequate security?

Oftentimes, when you inquire about the API security tools an organization uses, they will cite that they have an API gateway and a web application firewall. However, though API gateways provide very much needed basic API security controls, they unfortunately are not enough to adequately protect your business from API specific threats. As we mentioned above, an API gateway is critical for API management, not security.

For example, Broken Object Level Authorization (BOLA) attacks appear as normal API traffic to gateways. This lack of contextual awareness between API requests and responses enables these attacks to pass through undetected and access critical backend services. This gap can leave you vulnerable not only to BOLA exploits, but other attacks and business logic abuse. Ones that simply cannot be easily identified using standard API gateways.

Another gap in visibility involves maintaining an accurate API inventory. Enterprises manage thousands of APIs, many of which are not routed through a proxy such as an API gateway. The are referred to as rogue or zombie APIs. These APIs were likely deployed by previous employees and/or before your organization got serious about API security. Without visibility into how many APIs you have, it becomes easy to underestimate just how big your API estate really is.

Can Noname Security integrate with your API gateways?

Yes, the Noname API Security Platform integrates with your existing API gateways, web application firewalls, and other legacy infrastructure. From code to production, Noname encompasses all aspects of API security and has crafted our portfolio around the four recommended strategies solidified by Gartner:

API Discovery

Our API discovery tool finds and inventories all your APIs, including RESTful, GraphQL, SOAP, XML-RPC, JSON-RPC, and gRPC. The discovery module also uncovers legacy, rogue, and shadow APIs that were likely deployed before your existing AppSec team was in place.

API Posture Management

The Posture Management module provides a clear and accurate picture of your vulnerabilities and potential exposures. It uncovers what your true attack surface looks like across APIs and web applications. It also uncovers the type of sensitive data that traverses your APIs so you can remain compliant with data privacy regulations.

API Runtime Protection

Our platform uses automated AI and machine learning detection to conduct real time traffic analysis. It also provides contextual insights into data leakage, data tampering, data policy violations, suspicious behavior, and API security attacks.

API Active Testing

Our suite of API-focused security tests can run on-demand or as part of a CI/CD pipeline. These tests ensure that APIs aren’t implemented with security vulnerabilities in them.

Click here to learn more about how the Noname Security platform integrates with your existing API gateways to provide holistic API security.

API Gateway FAQs

How do API gateways work?

As an API management tool and reverse proxy, an API gateway handles API traffic and routes it to the proper backend services. The API gateway also performs the necessary translation between different services and the client application to deliver the user’s expected results.

  • The client or user sends a REST or API request and the API gateway intercepts.
  • The API gateway validates the request and filters it based on its rules.
  • The gateway routes the request to the proper service.
  • The backend service processes the request and sends a response to the API gateway.
  • The gateway sends the response to the client or user and may perform additional actions before doing so.

One issue that can occur with API gateways is too many API requests going back and forth between remote systems, leading to the need to perform API discovery to make sure there aren’t any errant requests going unnoticed.

Why should I have API gateway security?

Because an API gateway sits at the center of API traffic and your API management, it can become a target for bad actors. The increased implementation of and reliance on APIs means there’s also an increase in risk when an API lacks security features or an API security platform. An attack can inject malicious code or overwhelm the gateway.

API gateway security helps to ensure there’s no unauthorized access, data theft, data manipulation, or exploitable API vulnerabilities. You should fortify your API protocols and API gateway with robust API security measures as well as a complete security platform to prevent anything negative from happening.

What is the difference Between an API and an API gateway?

An API specifies endpoints that allow client servers or software to interact with another application, server, or service. An API consists of specifications, rules, and software architecture usually representative of a microservice. A microservice consists of one part of a larger application that an API allows direct access to.

An API gateway sits between the client and microservices as an interface rather than a server. In this capacity, the gateway manages and optimizes the interactions between the client and the endpoint. In the case of microservices, the gateway also routes the API call to the proper service.

Your APIs and API gateway need API security testing and an API security checklist to ensure you’re not overlooking anything. You can use NoName Security to integrate with your existing API gateways and provide optimal API security.

Harold Bell

Harold Bell was the Director of Content Marketing at Noname Security. He has over a decade of experience in the IT industry with leading organizations such as Cisco, Nutanix, and Rubrik, and has been featured as an executive ghostwriter in Forbes Technology Council and Hacker News.

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