Kubernetes tutorial   2019-10-28


kubernetes.io

1. Kubernetes what?

Kubernetes (K8s) is an open-source system for automating deployment, scaling, and management of containerized applications.

Kubernetes minikube install @Mac

sysctl -a | grep -E --color 'machdep.cpu.features|VMX' 

brew cask install minikube

同時它也會一起安裝 kubectl 這個 Kubernetes 指令操作工具 kubectl

minikube version

# /tmp/fluentd/etc [9:47:26]
➜ minikube version
minikube version: v1.5.0
commit: d1151d93385a70c5a03775e166e94067791fe2d9

minikube 主要是用在練習和教學使用, 非生产环境.

Kubernetes is growing rapidly, has become a leader in Container Orchestration

2. Kubernetes why?

生产环境应用会包含多个 Containers,而这些 Containers 还很可能会跨越多个服务器主机部署。

  1. Kubernetes 提供了为那些工作负载大规模部署 Container 的编排与管理能力.
  2. Kubernetes 编排能构建多容器应用服务,在集群上调度或伸缩这些容器,及管理它们随时间变化的健康状态.

Kubernetes 也需要与网络、存储、安全、监控等其它服务集成才能提供综合性的容器基础设施。

有了 Kubernetes,你可以:

  • 跨主机编排 Container;
  • 控制与自动化应用的部署与升级。
  • 为有状态的 Application 挂载和添加存储器。
  • 线上扩展或裁剪 Containerized applications 与它们的资源。
  • 声明式的容器管理,保证所部署的应用按照我们部署的方式运作。
  • 通过自动布局、自动重启、自动复制、自动伸缩实现应用的状态检查与自我修复。

Kubernetes 依赖其它项目来提供完整的编排服务。结合其它必要开源项目作为其组件:

  • 仓库:Atomic Registry、Docker Registry 等。
  • 网络:OpenvSwitch 和智能边缘路由等。
  • 监控:heapster、kibana、hawkular 和 elastic。
  • 安全:LDAP、SELinux、 RBAC 与 支持多租户的 OAUTH。
  • 自动化:通过 Ansible 的 playbook 进行集群的安装和生命周期管理。
  • 服务:大量事先创建好的常用应用模板。

红帽 OpenShift 为容器部署预先集成了上面这些组件。

3. Kubernetes architecture

Kubernetes 支持在多种环境下的安装:

  1. 本地主机(Fedora)
  2. 云服务(Google GAE、AWS)

3.1 K8s architecture

kubernetes.io

3.2 Master

Master有三个组件:API Server、Scheduler、Controller:

  1. API Server 是整个系统的对外接口,提供 RESTful 方式供客户端和其它组件调用;
  2. Scheduler 负责对资源进行调度,分配某个 pod 到某个节点上;
  3. Controller-manager 负责管理控制器,包括 endpoint-controller(刷新服务和 pod 的关联信息)和 replication-controller(维护某个 pod 的复制为配置的数值)。

3.3 Node

Kubernetes Node

集群中的每个非 master 节点都运行两个进程:

  • kubelet,和 master 节点进行通信。
  • kube-proxy,一种网络代理,将 Kubernetes 的网络服务代理到每个节点上。

3.4 Kubernetes 术语

  • Master(主节点): 控制 Kubernetes 节点的机器,也是创建作业任务的地方。

  • Node(节点): 这些机器在 Kubernetes 主节点的控制下执行被分配的任务。

  • Pod: 由一个或多个容器构成的集合,作为一个整体被部署到一个单一节点。

      同一个 pod 中的容器共享 IP 地址、进程间通讯(IPC)、主机名以及其它资源。

      Pod 将底层容器的网络和存储抽象出来,使得集群内的容器迁移更为便捷。

  • Replication controller: 控制一个 pod 在集群上运行的实例数量。
  • Service: 将服务内容与具体的 pod 分离。Kubernetes 服务代理负责自动将服务请求分发到正确的 pod 处.
  • Kubelet: 这个守护进程运行在各个工作节点上,负责获取容器列表,保证声明的容器已经启动且正常运行。
  • kubectl: 这是 Kubernetes 的命令行配置工具。

更多内容请查看 Kubernetes 术语表

4. Quickstart minikube

启动 Kubernetes cluster

4.1 Start Minik & create cluster

Start Minikube and create a cluster

# /tmp/fluentd/etc [14:03:57]
➜ minikube start
😄 minikube v1.5.0 on Darwin 10.14.6
✨ Automatically selected the 'hyperkit' driver
💾 Downloading driver docker-machine-driver-hyperkit:

4.2 create a k8s Deployment

Let’s create a Kubernetes Deployment using an existing image named echoserver, which is a simple HTTP server and expose it on port 8080 using --port.

➜ kubectl create deployment hello-minikube --image=k8s.gcr.io/echoserver:1.10
deployment.apps/hello-minikube created

4.3 hello-minikube Deployment

To access the hello-minikube Deployment, expose it as a Service:

➜ kubectl expose deployment hello-minikube --type=NodePort --port=8080
service/hello-minikube exposed

4.4 view hello-minikube Pod

The hello-minikube Pod is now launched but you have to wait until the Pod is up before accessing it via the exposed Service.

If the output shows the STATUS as Running, the Pod is now up and running:

➜ kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-minikube-797f975945-nrb6r 1/1 Running 0 2m14s
(anaconda3) (base)

kubectl get cmd:

kubectl get node
kubectl get po,svc -n kube-system

4.5 view the Service details

Get the URL of the exposed Service to view the Service details:

➜ minikube service hello-minikube --url
http://192.168.64.2:30799
(anaconda3) (base)

Output:

Hostname: hello-minikube-797f975945-nrb6r

Pod Information:
-no pod information available-

Server values:
server_version=nginx: 1.13.3 - lua: 10008

Request Information:
client_address=172.17.0.1
method=GET
real path=/
query=
request_version=1.1
request_scheme=http
request_uri=http://192.168.64.2:8080/

Request Headers:
accept=text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
accept-encoding=gzip, deflate
accept-language=zh-CN,zh;q=0.9,zh-TW;q=0.8,en-US;q=0.7,en;q=0.6
connection=keep-alive
host=192.168.64.2:30799
upgrade-insecure-requests=1
user-agent=Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.120 Safari/537.36

Request Body:
-no body in request-

4.6 delete hello-minik service

kubectl delete services hello-minikube

4.7 delete hello-minik deploym

销毁该 Deployment(和它的 pod)

kubectl delete deployment hello-minikube

4.8 stop Minikube cluster

minikube stop

4.9 delete Minikube cluster

minikube delete

5. Kubernetes hexo

Docker 用户使用 kubectl 命令指南

Kubernetes 支持两种方式创建资源

  1. 用 kubectl 命令直接创建,比如:
kubectl run nginx-deployment --image=nginx:1.7.9 --replicas=2

在命令行中通过参数指定资源的属性.
  1. 通过配置文件和 kubectl apply 创建,要完成前面同样的工作,可执行命令:
kubectl apply -f nginx.yml

kubectl apply 不但能够创建 Kubernetes 资源,也能对资源进行更新,非常方便。

Kubernets 还提供了几个类似的命令,例如:

  1. kubectl create, kubectl replace
  2. kubectl edit, kubectl patch

5.1 kubectl cluster-info cmd

kubectl cluster-info

➜ kubectl cluster-info
Kubernetes master is running at https://192.168.64.2:8443
KubeDNS is running at https://192.168.64.2:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

kubectl get po,svc -n kube-system

➜ kubectl get po,svc -n kube-system
NAME READY STATUS RESTARTS AGE
pod/coredns-5644d7b6d9-2qtds 1/1 Running 0 25h
pod/coredns-5644d7b6d9-w8442 1/1 Running 0 25h
pod/etcd-minikube 1/1 Running 0 25h
pod/kube-addon-manager-minikube 1/1 Running 0 25h
pod/kube-apiserver-minikube 1/1 Running 0 25h
pod/kube-controller-manager-minikube 1/1 Running 1 25h
pod/kube-proxy-k2pgh 1/1 Running 0 25h
pod/kube-scheduler-minikube 1/1 Running 2 25h
pod/storage-provisioner 1/1 Running 0 25h

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP,9153/TCP 25h

5.2 Create deployment hexo4

kubectl run --image=blair101/ubuntu-hexo-blog:v1.4 hexo4 --port=4000 --env="DOMAIN=cluster"

创建一个 deployment, name: hexo4, 也会生成一个 pod, 可通过 kubectl edit deploy hexo4 修改副本数为2

➜ kubectl get deploy,svc
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/hexo4 2/2 2 2 8m34s

NAME READY STATUS RESTARTS AGE
pod/hexo4-67f54d9bd9-8gzt9 1/1 Running 0 8m34s
pod/hexo4-67f54d9bd9-dvzht 1/1 Running 0 3s

k8s 端口映射

查看详细 deploy hexo4 -o yaml

kubectl get deploy hexo4 -o yaml
apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
creationTimestamp: null
generation: 1
labels:
run: hexo4
name: hexo4
selfLink: /apis/apps/v1/namespaces/default/deployments/hexo4
spec:
progressDeadlineSeconds: 600
replicas: 2
revisionHistoryLimit: 10
selector:
matchLabels:
run: hexo4
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
run: hexo4
spec:
containers:
- env:
- name: DOMAIN
value: cluster
image: blair101/ubuntu-hexo-blog:v1.4
imagePullPolicy: IfNotPresent
name: hexo4
ports:
- containerPort: 4000
protocol: TCP
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
status: {}
(anaconda3) (base)

一些常用命令记录:

kubectl describe po hexo4-67f54d9bd9-ffnsp

kubectl exec -it hexo4-67f54d9bd9-ffnsp bash

kubectl get po hexo4-5b97779b7c-8z8ns -o yaml --export

kubectl get deploy hexo4 -o yaml --export | tee deploy-v1.yaml
kubectl apply -f deploy-v5.yaml

5.3 Create service hexo4

kubectl expose deployment hexo4 --port=4000 --name=hexo4

查看 service, kubectl edit svc hexo4

➜ kubectl get deploy, po, svc
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/hexo4 2/2 2 2 54m

NAME READY STATUS RESTARTS AGE
pod/hexo4-67f54d9bd9-8gzt9 1/1 Running 0 54m
pod/hexo4-67f54d9bd9-dvzht 1/1 Running 0 45m

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/hexo4 ClusterIP 10.97.151.174 <none> 4000/TCP 35s
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 26h

查看 service hexo4 详情:

➜ kubectl get svc -o yaml hexo4
apiVersion: v1
kind: Service
metadata:
creationTimestamp: "2019-10-30T03:56:49Z"
labels:
run: hexo4
name: hexo4
namespace: default
resourceVersion: "48479"
selfLink: /api/v1/namespaces/default/services/hexo4
uid: e1c9c30b-d3b8-4625-9817-a14ea3677bd3
spec:
clusterIP: 10.97.151.174
ports:
- port: 4000
protocol: TCP
targetPort: 4000
selector:
run: hexo4
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
(anaconda3) (base)

5.4 kubectl edit service hexo4

kubectl edit service hexo4

type: ClusterIP --> NodePort 且 spec.ports 增加 nodePort: 30001

spec:
clusterIP: 10.107.236.48
externalTrafficPolicy: Cluster
ports:
- nodePort: 30001
port: 4000
protocol: TCP
targetPort: 4000
selector:
run: hexo4
sessionAffinity: None
type: NodePort

5.5 build hexo5, deploy ervice

create deployment hexo5

kubectl run --image=blair101/ubuntu-hexo-blog:v1.5 hexo5 --port=4000 --env="DOMAIN=cluster"

create service hexo5

kubectl expose deployment hexo5 --port=4000 --name=hexo5

kubectl edit service hexo5

type: ClusterIP --> NodePort 且 spec.ports 增加 nodePort: 30001

5.6 modify service hexo4

更改 selector.run: hexo4 为 hexo5

spec:
clusterIP: 10.107.236.48
externalTrafficPolicy: Cluster
ports:
- nodePort: 30001
port: 4000
protocol: TCP
targetPort: 4000
selector:
run: hexo5
sessionAffinity: None
type: NodePort

接下来是一些 delete 操作.

Reference


分享到:


  如果您觉得这篇文章对您的学习很有帮助, 请您也分享它, 让它能再次帮助到更多的需要学习的人. 您的支持将鼓励我继续创作 !
本文基于署名4.0国际许可协议发布,转载请保留本文署名和文章链接。 如您有任何授权方面的协商,请邮件联系我。

Contents

  1. 1. Kubernetes what?
  2. 2. Kubernetes why?
  3. 3. Kubernetes architecture
    1. 3.1 K8s architecture
    2. 3.2 Master
    3. 3.3 Node
    4. 3.4 Kubernetes 术语
  4. 4. Quickstart minikube
    1. 4.1 Start Minik & create cluster
    2. 4.2 create a k8s Deployment
    3. 4.3 hello-minikube Deployment
    4. 4.4 view hello-minikube Pod
    5. 4.5 view the Service details
    6. 4.6 delete hello-minik service
    7. 4.7 delete hello-minik deploym
    8. 4.8 stop Minikube cluster
    9. 4.9 delete Minikube cluster
  5. 5. Kubernetes hexo
    1. 5.1 kubectl cluster-info cmd
    2. 5.2 Create deployment hexo4
    3. 5.3 Create service hexo4
    4. 5.4 kubectl edit service hexo4
    5. 5.5 build hexo5, deploy ervice
    6. 5.6 modify service hexo4
  6. Reference