Pre-requisite to Understand This

Before diving in, it helps to have basic knowledge of:

If we understand “a client sends a request and a backend processes it”, we are good to proceed.

Introduction

In modern cloud-native and microservices-based deployments, applications are no longer hosted on a single server. Instead, they run across multiple services, containers, and nodes that must be accessed reliably and securely. To manage incoming traffic and ensure scalability, availability, and security, architectures commonly use a combination of a Load Balancer, an Ingress Controller, and an API Gateway. Each of these components plays a distinct role at different layers of the system, and together they form a robust traffic management and API governance solution.

To manage traffic efficiently, securely, and reliably, we introduce three key components:

ComponentPrimary Role
Load BalancerDistributes traffic across multiple servers
Ingress ControllerRoutes external traffic into Kubernetes services
API GatewayManages, secures, and governs APIs

They work together, not as replacements for each other.

What problem we can solve?

Without these components, systems face serious challenges:

Problems Without Them

Problems Solved

How to Implement This?

Typical Deployment Flow (High Level)

SeqDepComp

In a typical deployment, the client sends a request to the system, which first reaches an external Load Balancer. The Load Balancer distributes incoming traffic across multiple nodes and often handles SSL termination. The request is then forwarded to the Kubernetes Ingress Controller, which applies host- and path-based routing rules to determine which internal service should receive the request. The traffic is then passed to the API Gateway, which enforces cross-cutting concerns such as authentication, authorization, rate limiting, logging, and monitoring. Finally, the request is routed to the appropriate microservice, which processes the business logic and returns a response that flows back through the same path to the client.

Component Responsibilities

Load Balancer

Ingress Controller (Kubernetes)

API Gateway

Advantages

  1. Scalability: Automatically scales services and traffic handling

  2. High Availability: No single point of failure

  3. Security: Centralized authentication and authorization. Hides internal services

  4. Observability: Centralized logging, metrics, and tracing

  5. Maintainability: Clean separation of concerns, easier updates and deployments

Summary

API Gateways, Load Balancers, and Ingress Controllers each serve a specific purpose in a deployment solution, operating at different layers of the architecture. The Load Balancer manages external traffic distribution, the Ingress Controller routes traffic within Kubernetes, and the API Gateway governs and secures API access. When combined, these components create a scalable, secure, and resilient deployment architecture that is well suited for modern microservices-based applications.