Ingress in Kubernetes is an API resource that manages external HTTP and HTTPS access to services running inside a Kubernetes cluster. It allows users to access applications through a common entry point using domain names, URL paths, and routing rules. Instead of exposing every application separately, Ingress can direct incoming traffic to the appropriate internal service.
Here are some important features of Kubernetes Ingress.
1. Routing Traffic to Services
Ingress routes incoming requests to backend services based on configured rules. For example, requests to example.com/api can be directed to an API service, while requests to example.com/shop can be sent to an online shopping application.
2. Domain-Based Routing
Ingress supports host-based routing, allowing multiple applications to use different domain names while sharing the same external entry point. This makes application access easier to manage.
3. HTTPS and TLS Support
Ingress can be configured to handle HTTPS traffic using TLS certificates. This helps encrypt communication between clients and the entry point. Certificate management may be integrated with tools such as cert-manager.
4. The Role of an Ingress Controller
An Ingress resource defines routing rules, but it does not process traffic by itself. An Ingress controller, such as NGINX Ingress Controller or a supported cloud-provider controller, watches these resources and configures the infrastructure to apply the rules.
5. Load Balancing
Ingress controllers can distribute incoming requests across backend service endpoints. They may also provide additional capabilities such as request timeouts, redirects, and access restrictions, depending on the controller and its configuration.
6. Ingress vs. Service
A Kubernetes Service provides a stable way to access a group of application pods inside the cluster or, depending on its type, from outside the cluster. Ingress focuses on HTTP and HTTPS routing from external clients to those services. A Service of type LoadBalancer is another common way to expose an application externally.
7. Ingress vs. Gateway API
Ingress remains widely used, but Kubernetes Gateway API provides a more expressive approach to traffic management, with additional routing capabilities and clearer separation of responsibilities. Kubernetes recommends evaluating Gateway API for new requirements where its features are useful.
For example, suppose a company runs a website, an API, and an admin dashboard in the same Kubernetes cluster. An Ingress controller can route example.com to the website, example.com/api to the API service, and admin.example.com to the dashboard. This allows the company to manage external HTTP and HTTPS access through a common routing layer.
In conclusion, Ingress is a useful Kubernetes resource for managing external web traffic efficiently. It supports host-based and path-based routing and can work with TLS to secure application access. To use it successfully, teams need a compatible Ingress controller and correctly configured backend services. Understanding Ingress is especially valuable for DevOps engineers who manage Kubernetes deployments, application networking, and production environments.