What is ingress and egress in Kubernetes?
In Kubernetes, ingress and egress are two terms used to describe how traffic enters and exits a cluster.
Basic Kubernetes ingress. Ingress refers to the process of routing external traffic into the Kubernetes cluster. In other words, it is the entry point for incoming traffic to the services running within the cluster. Kubernetes provides a basic Ingress resource that allows you to define rules for how traffic should be routed from external sources to your services. An Ingress controller is responsible for implementing these rules.
Basic Kubernetes egress. Egress refers to the process of traffic leaving the Kubernetes cluster and going to an external destination. This traffic can be initiated from within the cluster by a pod or service. Kubernetes provides an Egress resource that allows you to define rules for how traffic should be routed from your services to external destinations.
Full-featured Kubernetes ingress. Implementations of the new Kubernetes Gateway API such as Envoy Gateway offer full-featured application gateway functionality for traffic ingress to Kubernetes clusters.
Advanced Kubernetes ingress and egress with a service mesh. Service meshes like Istio provide advanced ingress and egress capabilities. Istio provides a Kubernetes ingress gateway, which is a load balancer that manages incoming traffic from outside the cluster. The ingress gateway can be configured to route traffic to the appropriate microservice based on the incoming request’s URL or headers.
Istio also provides an egress gateway, which is a load balancer that manages outgoing traffic from the Kubernetes cluster. The egress gateway can be used to route traffic to external services or APIs, as well as to apply security policies and enforce rate limiting.
Additionally, Istio provides features for managing traffic routing and load balancing between microservices within a Kubernetes cluster. It can automatically route traffic between services based on various factors, such as round-robin or weighted load balancing, client affinity, or custom routing rules.
Enterprise solutions like Tetrate Service Bridge offer a global application connectivity and security platform for an entire fleet of applications across clusters, clouds, and on-premises.
For more information, read our Learning Center article on Istio