What Are Ingress Controllers in Kubernetes? A DevOps Guide

Did you know? Ingress controllers route incoming traffic from outside the cluster to specific services running within the cluster based on predefined rules (e.g., path, host, port). (Source)

Today, we are all witnessing major leaps in the technological domains of computer hardware and software that are aiming to streamline human efforts. 

Kubernetes Ingress Controllers play a key role in managing external access to services, especially for web traffic (HTTP/HTTPS). But many  DevOps tools operators find them confusing because of their complex algorithms and distinctive frameworks. 

But using new-gen devices, they can optimize traffic routing, helping businesses reduce infrastructure costs while improving scalability and security.

In this blog post, we are going to closely analyze their algorithms, providing valuable insights to the readers. 

Let’s begin!

Key Takeaways 

• Understanding everything about the ingress controller
• Exploring how an ingress controller works  
• Discovering all the challenges solved by this technology
• Uncovering why it is used by the majority of DevOps 

What is an Ingress Controller?

An Ingress is basically a Kubernetes thing that shows how people from outside can get to the services chilling in your cluster. Think of it as a traffic guide for incoming requests. It helps the cluster know where to send those requests based on simple rules, like hostnames or paths.

However, an Ingress by itself doesn’t do anything. It’s just a set of rules. For these rules to route traffic, you need an Ingress Controller.

An Ingress Controller is a specialized load balancer running inside your Kubernetes cluster. It watches for Ingress resource changes and uses the defined rules to route incoming traffic to the appropriate backend services (Pods).

How Does an Ingress Controller Work?

Let’s keep it simple.

You’ve got some awesome apps humming away in your Kubernetes cluster. They’re doing their thing well, but they’re kind of private. No one from outside the cluster can just pop in and use them.

Now, a user wants to access your web app. They hit my app. company.com.

What happens next?

Step 1: The DNS directs the request

That domain is linked to a load balancer. This load balancer knows how to send traffic into your Kubernetes cluster.

Step 2: The Ingress Controller picks it up

Within your cluster resides the Ingress Controller, which diligently monitors all incoming traffic. However, it does not merely transmit data indiscriminately.

Instead, it checks the Ingress rules you defined.

These rules say things like:

“If someone goes to /login, send them to the auth service.”

“If the request is for api.company.com, forward it to the backend API.”

Step 3: It matches the request

The Ingress Controller looks at the incoming request:

What’s the domain?

What’s the path?

Is it HTTP or HTTPS?

Should a corresponding rule be identified, it precisely determines the appropriate destination for the request within your cluster.

Step 4: It routes the traffic

The Ingress Controller sends the request to the right Service inside Kubernetes.

That Service routes it to one or more Pods that are running your app.

And then, 

Your app responds.

Step 5: It can handle TLS (HTTPS)

As long as your app is cool with HTTPS, the Ingress Controller can totally do TLS termination too. That means:

It decrypts the incoming traffic.

Then sends it securely into the cluster.

So your internal services don’t need to worry about certificates.

And that’s it.

The Ingress Controller acts like a programmable gateway.

It diligently monitors all traffic, adheres to established protocols, and ensures that your services remain both accessible and secure.

Intriguing Insights 

This infographic shows the complete functioning of Ingress controllers.

What Challenge Does an Ingress Controller Solve?

One of the biggest challenges in Kubernetes-based environments is exposing services to the outside world. Kubernetes services are, by default, accessible solely within the confines of the internal cluster network. While this isolation enhances security measures, it presents challenges when there is a need for users, clients, or external systems to engage with your applications.

You do have a couple of built-in options like NodePort and LoadBalancer, but both come with trade-offs that can quickly become bottlenecks as your system grows.

NodePort exposes each service on a static high port across all cluster nodes. While it’s easy to set up initially, it can create major headaches in the long run. It gets messy to keep track of separate ports for each service as your business grows. And from a security standpoint, exposing random high ports publicly isn’t ideal.

On the other hand, LoadBalancer provisions a dedicated cloud load balancer for each service. This works well for a few critical services, but gets expensive and hard to manage if you’re deploying dozens or hundreds of services. Each service ends up with its external IP and configuration, adding both operational and financial overhead.

Ingress Controllers facilitate the effective management of network traffic. Rather than assigning a unique port or load balancer to each service, one can establish a singular Ingress resource. This resource is responsible for accurately directing traffic to the appropriate services according to hostnames or URL paths. It’s like a traffic manager at the edge of the cluster. It receives requests and sends them to the right service.

With Ingress Controllers, you centralize your routing logic, reduce costs, improve scalability, and eliminate port chaos. This solution is designed for modern, fast-moving DevOps environments where flexibility and automation are key.

Interesting Facts 
Ingress controllers can be scaled to handle increasing traffic loads, ensuring high availability and performance, according to Kong Inc.

Why Every DevOps Team Needs an Ingress Controller

Ingress Controllers represent a fundamental component of contemporary application delivery within the Kubernetes ecosystem. For DevOps teams managing the complexities of deployments, scalability, and security, Ingress Controllers provide essential control and automation capabilities. Let us explore the factors that contribute to their significant value:

1. Centralized Traffic Management

Administrative traffic for multiple services can turn into a mess real quick. Without a central controller, teams often use NodePort or separate load balancers. That means more configs, more costs, and way more room for errors. But with an Ingress Controller, you manage everything from a single source of truth. One Ingress file can define routing for all your apps across all environments. You get better visibility, fewer mistakes, and way easier audits. It also helps Dev and Ops stay on the same page.

When you add GitOps or IaC into the mix, it gets even better. Now your traffic rules are version-controlled. Every change goes through a pull request. Everyone knows who changed what and why. It’s collaboration made simple.

2. TLS Termination & Simplified Security

Honestly, managing HTTPS manually isn’t fun. Every app needs certificates. Every certificate needs renewal. It’s a lot of effort. Ingress Controllers take that pain away by handling TLS at the edge. They decrypt traffic before it hits your app, so you don’t have to deal with it internally. This keeps your internal traffic clean and your setup secure.

Most Ingress Controllers also support cert-manager out of the box. That means automatic SSL issuance and renewal. 

No manual setup, no missed deadlines.  Your domains stay secure 24/7.  That’s peace of mind for your team and your users.

3. Path-Based & Host-Based Routing

Need to split traffic based on URLs or subdomains? Ingress makes that easy. Send /api to your backend and /app to your frontend—all from one entry point. You can even map subdomains like login.company.com and billing.company.com to different services. It’s clean, efficient, and doesn’t need extra load balancers. This kind of smart routing is great for microservices and modern apps. It simplifies complexity and keeps your setup scalable.

Some Ingress Controllers let you route based on headers. This means more control for you, which is awesome for testing things out, doing canary releases, or creating specific flows for different tenants. You can tweak traffic easily with just a few lines of config. And the best part? You manage it all from one spot.

4. Built-in Load Balancing & Scalability

In the event of traffic surges, there is no cause for concern. Ingress Controllers are equipped with integrated load-balancing features. They efficiently distribute incoming requests among your pods utilizing sophisticated techniques such as round-robin, least connections, or IP-hash. Additionally, they monitor the health of the pods to ensure optimal performance. If one fails, traffic gets rerouted automatically. That means higher uptime and smoother performance.

As your services scale, Ingress updates routes dynamically. There’s no need to tweak anything manually. It’s plug-and-play for horizontal scaling. Just focus on your code; Ingress handles the rest.

5. Seamless Integrations: cert-manager & External DNS

DevOps thrives on integration. Ingress Controllers work with tools like cert-manager, external-dns, Helm, and ArgoCD. You can deploy Ingress rules with your CI/CD pipeline. DNS updates? Automated. SSL certs? Handled. Git-based deployments? Absolutely.

These tools work better together when Ingress is in the mix. You reduce manual work and increase speed. Everything becomes repeatable and trackable. It’s the kind of workflow DevOps teams dream of. Fast, clean, and error-free.

In conclusion, while ingress controllers may not garner public attention, they quietly facilitate several of the most critical components of Kubernetes-based deployments. They simplify routing, strengthen security, and make scaling effortless, all from a single control point. Centralized control significantly benefits DevOps teams by helping them balance speed, automation, and reliability. Centralized routing logic, dynamic load balancing, and built-in TLS termination are all essential components that ensure the smooth and reliable operation of applications without introducing additional workload.

An Ingress Controller is more than just a traffic manager, it helps teams adopt DevOps practices. It enhances automation and facilitates seamless integrations, establishing the efficient infrastructure that contemporary teams require. Employing an ingress controller is crucial for optimizing your Kubernetes and DevOps methodologies..

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