Kubernetes / 4.Kubernetes Quick Start

Kubernetes Quick Start

By studying this section, you can fully understand its role required a certificate of kubernetes https clusters, and resource types api territory kubernetes language, finally, I also added a couple of basic GET command, then you can Log on to the previous chapter we used cluster kubeadm created some of the query.

• Certificate Management
• API resource model
• API resource types
• Supplementary command
• Remark

Certificate Management

k8s running in a production environment, I strongly suggest that you run under https secure environment, its certificate can be divided into the following three categories:

root CA：

• apiserver: apiserver own certificate
• apiserver-kubelet-client: kubelet client connection client certificate when apiserver

etc.Her CA:

• etcd-server: etcd server certificate
• etcd-peer: etcd peer certificates, https for communication between the cluster ETCD
• Client Certificate etcd health check: etcd-healthcheck-client
• apiserver-etcd-client: apiserver connecting the client certificate ETCD

front-proxy CA：

• front-proxyserver-client: apiserver (Aggregator The Aggregator) to the front end of the client certificate

You need to note that:
1) K8S cluster certificate default validity period is 90 days, you have two ways to adjust (modify go source file or a certificate signing request is generated statement, how do I edit my later chapters would say)
2) certificate expired time, you can go to the / etc / under kubernetes / pki directory, use the following command to view:

openssl x509 -in front-proxy-client.crt   -noout -text  |grep Not
            Not Before: Nov 28 09:07:02 2018 GMT
            Not After : Nov 25 09:07:03 2028 GMT

openssl x509 -in apiserver.crt   -noout -text  |grep Not
            Not Before: Nov 28 09:07:04 2018 GMT
            Not After : Nov 25 09:07:04 2028 GMT

API resource model

RESTfulAPI的核心组件是“资源（resource）”，不同类别的事物会被抽象会不同“类型（type）”的资源。
k8s中的资源也类似于对象式编程语言中的“类"（class），但它仅支持有限的方法，而且通常是标准的HTTP方法，例如：GET、PUT、POST和DELETE；此时，你应该可以联想到常用的基础命令kubelet：

kubectl get pod
kubectl delete node
...

• 为了便于独立进行版本演进，Kubernetes将API划分为了称为“API群组”的逻辑集合，每个群组的REST路径为“/apis/$GROUP_NAME/$VERSION”，例如/apis/apps/v1；
• 核心群组core使用简化的REST路径/api/v1；
• 同时，每个群组可同时存在多个不同级别的版本，主要包括alpha、beta和stable三个，使用的级别标识如v1alpha1、v1beta2和v1等。

你可以通过api-versions命令查询当前所支持的API版本：

[root@k8s-etcd-mater01 cds-filesystem]# kubectl api-versions
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
apps/v1beta1
apps/v1beta2
authentication.k8s.io/v1
authentication.k8s.io/v1beta1
authorization.k8s.io/v1
authorization.k8s.io/v1beta1
autoscaling/v1
autoscaling/v2beta1
autoscaling/v2beta2
batch/v1
batch/v1beta1
certificates.k8s.io/v1beta1
coordination.k8s.io/v1beta1
events.k8s.io/v1beta1
extensions/v1beta1
networking.k8s.io/v1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1beta1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1

API资源类型

如图所示，Kubernetes系统把管理的绝大多数事物都抽象成了资源，它们分别代表着不同的事物类型，例如：Node、Service、Pod、Controller等等

• 每种类型均可通过“属性赋值”进行实例化，从而构建出“对象（object）；
• 对象主要用于描述要在集群中运行的“应用程序（Pod）”，以及应用程序相关的控制（controllers）、配置（ConfigMap和Secret）、服务暴露（Service和Ingress）、存储（Volume）等；
• 用户使用这些对象来规划、部署、配置、维护和监控应用程序并记录运行日志；
• 每种类型的资源对象都支持相应的一组方法（管理操作），它们可用标准的HTTP Verb进行表示，例如：GET、PUT、DELETE和POST等。

命令补充

    获取集群资源列表：
        kubectl  api-resources

    获取命名空间：
        kubectl  get ns

    创建deployment： 
        kubectl create deployment ngx-new --image=nginx

    查看service信息：
         kubectl describe svc ngx-new
    ...

备注

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