diff --git a/t/cka/daily.md b/t/cka/daily.md index c586584..9bb2079 100644 --- a/t/cka/daily.md +++ b/t/cka/daily.md @@ -41,6 +41,9 @@ CKA证书的含金量如何？考不考这个证完全取决于个人，因为 作为在Kubernetes技术上摸爬滚打1年多的老鸟，最近正准备备考CKA，鉴于此，我希望想证明自己kubernetes开发运维能力的小伙伴能一起从今天开始，我们一起每日一题，在留言区答题打卡，我会在其中选出3位认真并坚持打卡21天的小伙伴送出3本书。 [CKA每日一题 - Day 1](./daily/001.html) + [CKA每日一题 - Day 2](./daily/002.html) +[CKA每日一题 - Day 3](./daily/003.html) + diff --git a/t/cka/daily/002.md b/t/cka/daily/002.md index c97518a..2d70dfb 100644 --- a/t/cka/daily/002.md +++ b/t/cka/daily/002.md @@ -24,7 +24,7 @@ B. AttachDetachController + CSI-Attacher + CSI controller plugin C. Kubelet + CSI node plugin -答案及解析 +答案及解析 diff --git a/t/cka/daily/003.assets/image-20191123192840601.png b/t/cka/daily/003.assets/image-20191123192840601.png new file mode 100644 index 0000000..c01f095 Binary files /dev/null and b/t/cka/daily/003.assets/image-20191123192840601.png differ diff --git a/t/cka/daily/003.assets/image-20191123192926509.png b/t/cka/daily/003.assets/image-20191123192926509.png new file mode 100644 index 0000000..6984c6f Binary files /dev/null and b/t/cka/daily/003.assets/image-20191123192926509.png differ diff --git a/t/cka/daily/003.assets/image-20191123192959494.png b/t/cka/daily/003.assets/image-20191123192959494.png new file mode 100644 index 0000000..dd22ca5 Binary files /dev/null and b/t/cka/daily/003.assets/image-20191123192959494.png differ diff --git a/t/cka/daily/003.assets/image-20191123193035704.png b/t/cka/daily/003.assets/image-20191123193035704.png new file mode 100644 index 0000000..9ed335e Binary files /dev/null and b/t/cka/daily/003.assets/image-20191123193035704.png differ diff --git a/t/cka/daily/003.assets/image-20191123193109039.png b/t/cka/daily/003.assets/image-20191123193109039.png new file mode 100644 index 0000000..c50d9e8 Binary files /dev/null and b/t/cka/daily/003.assets/image-20191123193109039.png differ diff --git a/t/cka/daily/003.md b/t/cka/daily/003.md new file mode 100644 index 0000000..04daad0 --- /dev/null +++ b/t/cka/daily/003.md @@ -0,0 +1,140 @@ +--- +vssueId: 166 +# layout: StepLayout +sharingTitle: CKA备考打卡 - 每日一题 - Day 3 +description: CKA备考打卡 - 每日一题 - Day 3 +meta: + - name: keywords + content: Kubernetes,K8S,CKA,Certified Kubernetes Administrator +--- + +# CKA每日一题 --- Day 3 + + + + +通过单个命令创建一个deployment并暴露Service。deployment和Service名称为cka-1120，使用nginx镜像， deployment拥有2个pod + + +答案及解析 + + + +### 答案 + +``` sh +[root@liabio ~]# kubectl run cka-1120 --replicas 2 --expose=true --port=80 --image=nginx + +kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead. +service/cka-1120 created +deployment.apps/cka-1120 created + +[root@liabio ~]# kubectl get all | grep cka-1120 +pod/cka-1120-554b9c4798-7jcrb 1/1 Running 0118m +pod/cka-1120-554b9c4798-fpjwj 1/1 Running 0118m +service/cka-1120 ClusterIP 10.108.140.25 80/TCP 118m +deployment.apps/cka-11202/222118m +``` + +### 解析 + + + +官网中提供了详细的kubectl使用方法，位于REFERENCE--kubectl CLI--kubectl Commands标签下。即：[https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#run](https://mp.weixin.qq.com/s/V9Q7yewpE2Cm7jGiCmL1HA) + +kubectl run会创建deployment或者job来管理Pod，命令语法如下： + +``` sh +kubectl run NAME --image=image [--env="key=value"] [--port=port] [--replicas=replicas] [--dry-run=bool] [--overrides=inline-json] [--command] -- [COMMAND] [args...] +``` + +NAME指定deployment和service的名称； + +--replicas缩写-r，指定实例数，默认为1； + +--expose如果为true，会创建有ClusterIP的service，默认为false； + +--port表示容器暴露的端口，如果expose为true，该端口也是service的端口； + +--image指定容器用的镜像； + +--dry-run为true时，只打印将要发送的对象，而不真正发送它，默认为false。 + +创建名为cka-1120-01，带环境变量的deployment + +``` sh +kubectl run cka-1120-01 --image=nginx --env="DNS_DOMAIN=cluster.local" --env="POD_NAMESPACE=default" +``` + +创建名为cka-1120-02，带label的deployment + +``` sh +kubectl run cka-1120-02 --image=nginx --labels="app=nginx,env=prod" +``` + +还有一个--restart参数，默认为Always，如果设置为OnFailure，则job会被创建；如果设置为Never，则普通Pod会被创建。 + +``` sh +[root@liabio ~]# kubectl run cka-1120-03 --image=nginx --restart=OnFailure +kubectl run --generator=job/v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead. +job.batch/cka-1120-03 created +[root@liabio ~]# +[root@liabio ~]# kubectl run cka-1120-04 --image=nginx --restart=Never +pod/cka-1120-04 created +``` + +参数--schedule指定cronjob的定时规则，如果指定该参数，则会创建出cronjob + +``` sh +[root@liabio ~]# kubectl run pi --schedule="0/5 * * * ?" --image=perl --restart=OnFailure -- perl -Mbignum=bpi -wle 'print bpi(2000)' +cronjob.batch/pi created +``` + +目前不支持直接创建Statefulset、Daemonset等资源对象。 + +**kubectl run执行后，到底发生了什么？**有必要看看kubectl源码，入口函数在$GOPATH\src\k8s.io\kubernetes\cmd\clicheck\checkcliconventions.go中 + +![image-20191123192840601](./003.assets/image-20191123192840601.png) + +其中cmd.NewKubectlCommand为构建kubectl以及其子命令行参数。最终的执行业务逻辑的代码都在pkg\kubectl包下面。不同的子命令：apply、run、create入口对应的在pkg\kubectl\cmd下面： + +![image-20191123192926509](./003.assets/image-20191123192926509.png) + +最重要的o.Run(f, cmd, args)中会对kubectl run传入的参数进行一系列校验，填充默认值。 + +在360行调用o.createGeneratedObject根据不同的generator生成deployment、cronjob、job、pod等资源对象，并向apiserver发送创建请求。 + +如果设置了expose为true，在372行，同样的调用o.createGeneratedObject生成并创建service。 + +![image-20191123192959494](./003.assets/image-20191123192959494.png) + +方法第649行，根据不同的generator实现生成不同的资源对象。 + +![image-20191123193035704](./003.assets/image-20191123193035704.png) + +run命令对应的generator实现有以下几种，代码位于pkg\kubectl\generate\versioned\generator.go中的DefaultGenerators函数。 + +``` go +case"run": + generator = map[string]generate.Generator{ + RunV1GeneratorName: BasicReplicationController{}, + RunPodV1GeneratorName: BasicPod{}, + DeploymentV1Beta1GeneratorName: DeploymentV1Beta1{}, + DeploymentAppsV1Beta1GeneratorName: DeploymentAppsV1Beta1{}, + DeploymentAppsV1GeneratorName: DeploymentAppsV1{}, + JobV1GeneratorName: JobV1{}, + CronJobV2Alpha1GeneratorName: CronJobV2Alpha1{}, + CronJobV1Beta1GeneratorName: CronJobV1Beta1{}, + } +``` + +o.createGeneratedObject方法第689行对生成的资源对象向APIServer发送http创建请求。 + +![image-20191123193109039](./003.assets/image-20191123193109039.png) + +具体的kubectl run命令的代码，感兴趣的同学可以进一步深挖，我也会在后续的源码分析系列文章中进行更详细的解析。 + + + + +