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Kubernetes-Docker cluster management

Kubernetes introduction

Kubernetes is an open source Docker container orchestration system, Kubernetes referred to as K8S.

Schedule the nodes of the computing cluster and dynamically manage the jobs above

Group applications by logical unit by using the concepts of [labels] and [pods]

1. K8S is used to deploy, extend and manage container applications.

2. K8S provides a series of functions such as container orchestration, resource scheduling, auto scaling, deployment management, service discovery and so on.

3. The goal of Kubernetes is to make deployment containerized, simple and efficient.

4. Official website: http://www.kubernetes.io

Kubernetes characteristics

1. Self-repair

Restart failed containers in case of node failure, replace and redeploy to ensure the predicted number of copies; kill containers that fail health checks, and do not process client requests until they are ready to ensure that online services are not interrupted.

2. Elastic expansion

Use command, UI or automatic rapid expansion and reduction of application instances based on CPU usage to ensure high availability at peak concurrency of application business; recover resources at low peak time and run services at minimum cost

3. Automatic deployment and rollback

K8S uses rolling update applications to update one Pod at a time instead of deleting all Pod at the same time. If there are problems in the update process, the changes will be rolled back to ensure that the upgrade will not affect the business.

4. Service discovery and load balancing

K8S provides a unified access entry for multiple containers (internal IP address and UI DNS address), and all containers associated with load balancer, so that users do not have to consider the container IP problem.

5. Confidentiality and configuration management

Manage confidential data and application configuration. There is no need to expose sensitive data in the mirror to improve the security of sensitive data. And some commonly used configurations can be stored in K8S to facilitate the use of applications.

6. Storage choreography

Mounting external storage systems, whether from local storage, public clouds (such as AWS), or network storage (NFS, GlusterFS) are used as part of cluster resources, greatly improving storage flexibility

7. Batch processing

Provide one-time tasks, scheduled tasks; meet the scenarios of batch data processing and analysis.

Kubernetes Cluster Architecture and components

Master component

1 、 kube-apiserver

Kubernetes API, the unified entrance to the cluster and the coordinator of each component, provides interface services through RESTful API. All object resource additions, deletions, modifications, and monitoring operations are handed over to APIServer and then submitted to Etcd for storage.

2 、 kube-controller-manager

Handle the regular background tasks in the cluster, each resource corresponds to a controller, and ControllerManager is responsible for managing these controllers.

3 、 kube-scheduler

Select a Node node for the newly created Pod according to the scheduling algorithm, which can be deployed arbitrarily, on the same node or on different nodes

4 、 etcd

Distributed key storage system, which is used to store cluster state data, such as Pod, Server and other object information.

Node component

1 、 kubelet

Kubelet is the Agent of MAster on the Node node, which manages the lifecycle of native running containers, such as creating containers, mounting data volumes on Pod, downloading secret, getting container and node status, and so on. Kubelet converts Pod into a set of containers.

2 、 bube-proxy

Implement Pod network agent on Noed node, maintain network planning and layer 4 complex = load balancing

3. Docker or rocker

Container engine, running container

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