Kubernetes 中的复制控制器 V/S 入口控制器

Question

Kubernetes 中的复制控制器和入口控制器有什么区别？

Answer 1

The Replication Controller is the original form of replication in Kubernetes. It's being replaced by Replica Sets, but it's still in wide use. A Replication Controller is a structure that enables you to easily create multiple pods, then make sure that that number of pods always exists. If a pod does crash, the Replication Controller replaces it.

Ingress exposes HTTP and HTTPS routes from outside the cluster to services within the cluster. Traffic routing is controlled by rules defined on the ingress resource. An ingress can be configured to give services externally-reachable URLs, load balance traffic, terminate SSL, and offer name based virtual hosting. An ingress controller is responsible for fulfilling the ingress, usually with a loadbalancer, though it may also configure your edge router or additional frontends to help handle the traffic.

In order for ingress resource to work, the cluster must have an ingress controller running. This is unlike other types of controllers, which run as part of the kube-controller-manager binary, and are typically started automatically with a cluster. Ingress Controllers can technically be any system capable of reverse proxying, but the most common is Nginx.

In a nutshell, replication controller is a controller which handles the pod replication in your cluster and makes sure you're running the desired number of replicas of pods. This controller comes as a part of kube-controller-manager by default. While Ingress controller is reverse proxy controller which is used to route the HTTP/HTTPS traffic from outside the cluster to services withing the kubernetes cluster.

Answer 2

Replication Controller is one of the key features of Kubernetes, which is responsible for managing the pod lifecycle. It is responsible for making sure that the specified number of pod replicas are running at any point of time. It is used in time when one wants to make sure that the specified number of pod or at least one pod is running. It has the capability to bring up or down the specified no of pod.

A Kubernetes Ingress controller is a specialized load balancer for Kubernetes environments. Kubernetes is the de facto standard for managing containerized applications. For many enterprises, moving production workloads into Kubernetes brings additional challenges and complexities around application traffic management. An Ingress controller abstracts away the complexity of Kubernetes application traffic routing and provides a bridge between Kubernetes services and external ones.

Kubernetes Ingress controllers:

• Accept traffic from outside the Kubernetes platform, and load balance it to pods (containers) running inside the platform
• Can manage egress traffic within a cluster for services which need to communicate with other services outside of a cluster
• Are configured using the Kubernetes API to deploy objects called “Ingress Resources”