Kubernetes Architecture (bottom)-5 minutes a day to play Docker container technology (121)

in the previous section we discussed the services running on the Kubernetes architecture Master,This section discusses node nodes.

Node is where the Pod runs, Kubernetes supports Docker, Rkt, and other container runtime. The Kubernetes components running on node have Kubelet, Kube-proxy, and Pod networks (such as flannel).

Kubelet

Kubelet is the agent of node, and when Scheduler determines that the pod is run on a node, the specific configuration information (image, volume, and so on) of the pod is sent to the kubelet,kubelet of the node to create and run the capacity based on that information. and report the running status to Master.

Kube-pro XY

The service logically represents multiple pods on the backend and the outside world accesses the pod through a service. How does the service receive the request forwarded to the Pod? This is the work that kube-proxy to accomplish.

Each Node runs the Kube-proxy service, which is responsible for sending the TCP/UPD data flow that accesses the service to the back-end container. If there are multiple replicas, kube-proxy is load balanced.

Pod Network

To be able to communicate with each other, the POD network must be deployed Kubernetes Cluster, and flannel is one of the options available.

The complete Architecture Figure

In combination with the experimental environment, we get the following architecture diagram:

You may ask: why are there kubelet and Kube-proxy on K8s-master?

This is because the app can also be run on master, that is, Master is also a Node.

Almost all of the Kubernetes components themselves run in pods, executing the following commands:

Kubectl Get pod--all-namespaces-o wide

Kubernetes system components are placed in thekube-systemthe namespace. Here's akube-dnscomponent, which provides DNS services for Cluster, which we will discuss later. kube-dnsis in the executionkubeadm init(step ⑤) installed as add-ons.

Kubelet is the only Kubernetes component that does not run as a container, and it runs through SYSTEMD in Ubuntu.

To help you better understand the Kubernetes architecture, we'll deploy an app to show how each component works together in the next section.

Books:

1.5 minutes of Docker container technology per day
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2.5 minutes of play with OpenStack per day
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Kubernetes Architecture (bottom)-5 minutes a day to play Docker container technology (121)