Ingress Controllers Overview

In this lesson, we dive deep into Kubernetes Ingress controllers and learn how they route external traffic into your cluster. Remember: an Ingress Resource defines the routing rules, but without an Ingress Controller, those rules are never enforced.

Ingress Resource vs Ingress Controller

An Ingress Resource is a Kubernetes object that declares hostname- and path-based routing rules. By itself, it performs no traffic routing.

An Ingress Controller is a Pod (or set of Pods) running inside the cluster. It monitors Ingress resources and programs the underlying proxy or load balancer to enforce those rules.

Aspect	Ingress Resource	Ingress Controller
Definition	Kubernetes object for routing rules	Component (Pod) that reads Ingress objects
Functionality	Declares host/path rules	Implements rules, load-balances traffic
Runtime	No running process	Runs inside cluster
Benefit	No effect without a controller	Routes external traffic to Services

The image is a comparison table between "Ingress Resource" and "Ingress Controller," highlighting aspects such as dependency, functionality, access and benefit, and nature.

Warning

Defining an Ingress without an active controller means no external traffic will reach your Services.

Kubernetes Architecture with Ingress

Clients send HTTP(S) requests to the cluster’s external endpoint. The Ingress controller intercepts these requests, matches them against Ingress rules, and forwards them to the appropriate Service, which then load-balances to the backend Pods.

The image is an architecture overview diagram showing a client interacting with a Kubernetes cluster through an ingress-managed load balancer, routing rules, and a service (SVC).

Cloud-based Ingress Controllers

Cloud providers offer managed Ingress controllers that integrate with native infrastructure services—load balancers, firewalls, IAM, and more—simplifying setup and scaling.

Controller	Cloud Provider	Key Features
AWS Load Balancer Controller	AWS	ALB & NLB provisioning, Auto scaling
Google Cloud Load Balancer	GCP	GKE integration, Global load balancing
Azure Application Gateway	Azure	SSL termination, WAF, path-based routing

Key benefits:

Automatic provisioning of cloud LoadBalancer resources
Built-in security features (WAF, IAM integration)
Managed upgrades and high availability
Reduced operational overhead

The image depicts a cloud-based architecture overview, showing a client connecting to an ingress controller, which routes through a load balancer to various services within a Kubernetes cluster.

The image shows an overview of cloud-based architecture featuring logos of Amazon Web Services (AWS), Google Cloud, and Microsoft Azure.

Non-cloud-based Ingress Controllers

Self-managed controllers run anywhere you choose—on-premises, private clouds, or public clouds where you handle cluster exposure. You’ll need to configure a Service of type LoadBalancer or NodePort to expose the Ingress controller externally.

Controller	Use Case	Highlights
NGINX Ingress Controller	General purpose	Reverse proxy, SSL/TLS, rate-limiting
Traefik	Dynamic auto-config	HTTP/HTTPS routing, metrics, dashboard
HAProxy Ingress	Performance-focused	Low-latency load balancing, TCP support

Deployment Models: Deployment vs DaemonSet

Choosing Deployment or DaemonSet affects how Ingress Pods are scheduled, how traffic is distributed, and resource consumption.

The image illustrates the deployment of ingress controllers, comparing "Deployments" and "DaemonSets" with their respective benefits. Deployments are easily scaled and resource-efficient but may have uneven load, while DaemonSets offer distributed load and high availability.

Option	Pros	Cons
Deployment	Dynamic scaling, resource-efficient	Uneven load distribution on nodes
DaemonSet	One Pod per node, uniform traffic distribution, high availability	Higher resource usage per node count

Note

Use Deployment when traffic patterns fluctuate and you want to optimize resource usage.
Use DaemonSet for uniform low-latency ingress on every node and built-in failover.

Factors to Consider

Before selecting an Ingress controller or deployment model, evaluate:

Traffic volume, throughput, and latency requirements
Scaling capabilities (static vs dynamic)
Features: supported protocols, SSL/TLS, middleware (auth, rate limiting)
Integration with your cloud or on-prem infrastructure
Configuration complexity and learning curve
API/automation support for CI/CD integration
Community support, plugin ecosystem, and commercial options
Cost: managed service fees vs self-managed resource costs
High availability, failover strategies, and load balancing algorithms

The image outlines factors to consider when deciding on an ingress controller, including performance, ease of use, features, support, cloud integration, and reliability.

References

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