kubernetes

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kubernetes 基础和一些概念

最困难的耗时间 | kubernetes-the-hard-way
工具：

kubectl

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# 节点
kubectl get node
# 节点详细信息
kubectl get node -o wide
# 上下文
kubectl context
# 获取不同的 context
kubectl config get-contexts
# 查看集群情况
kubectl cluster-info
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# 查看当前 minikube 生成集群的基本信息
kubectl config view

minikube

使用minikube创建虚拟机，在VirtualBox里面
需要安装kubernetskubectl brew install kubectl

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# 创建单节点的 K8s 集群
minikube start
minikube start --bootstrapper=localkube # 上面运行不成功就这个
minikube delete
# 进入 minikube 创建的 virtualbox 虚拟机
minikube ssh
# minikube web
minikube dashboard
  • 阿里云安装minikube
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# Mac OSX 验证
curl -Lo minikube http://kubernetes.oss-cn-hangzhou.aliyuncs.com/minikube/releases/v0.28.1/minikube-darwin-amd64 && chmod +x minikube && sudo mv minikube /usr/local/bin/
# Linux
curl -Lo minikube http://kubernetes.oss-cn-hangzhou.aliyuncs.com/minikube/releases/v0.28.1/minikube-linux-amd64 && chmod +x minikube && sudo mv minikube /usr/local/bin/

k8s

pod

最小的调度单位

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apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  # 定义容器 最重要的部分
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80 # 暴露的端口
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kubectl create -f pod_nginx.yml
kubectl delete -f pod_ngins.yml
kubectl get pods
kubectl get pods -o wide    # 显示容器的详细信息
kubectl exec -it nginx sh   # 进入容器
kubectl port-forward nginx 8080:80  # 映射 8080 到容器里面的 80
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~ kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
nginx     1/1       Running   0          1m
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~ kubectl get pods -o wide
NAME      READY     STATUS    RESTARTS   AGE       IP           NODE
nginx     1/1       Running   0          4m        172.17.0.4   minikube

横向扩展

  • ReplicsSet： v1 版本不支持，扩展
  • ReplicationController
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kubectl get pods
# 删除 pod 之后 k8s 会自动重启一个 pod
kubectl delete pods <pods name>
# 调整 nginx pod 为 2
kubectl scale rc nginx --replicas=2
kubectl get rc
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apiVersion: apps/v1
kind: ReplicaSet    # ReplicationController
metadata:
  name: nginx
  labels:
    tier: frontend
spec:
  replicas: 3   #  扩展 3 个 nginx
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      name: nginx
      labels:
        tier: frontend
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80

Deployments

  • example yaml file
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apiVersion: apps/v1
kind: Deployment    # 指定的类型
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3   # 保证这个 pods 里面至少是 3 个
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.12.2
        ports:
        - containerPort: 80
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# 操作示例
# 创建
kubectl create -f deployment_nginx.yml
kubectl get deployment  # 查看数量
kubectl get rs  # 有 dep 也会有这个
# 查看详细信息
kubectl get deployment -o wide

deployment
看 NAME 会一层一层的加

升级 image

实现平滑升级，过渡

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# 对 image 升级
kubectl set image deployment nginx-deployment  nginx=nginx:1.13

回滚

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$ kubectl get rs
NAME                          DESIRED   CURRENT   READY     AGE
nginx-deployment-7498dc98f8   0         0         0         17m
nginx-deployment-86cd46c4d9   3         3         3         7m
#----------------------------
$ kubectl get pods
NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment-86cd46c4d9-8zvtk   1/1       Running   0          7m
nginx-deployment-86cd46c4d9-bhn2d   1/1       Running   0          7m
nginx-deployment-86cd46c4d9-ltmn9   1/1       Running   0          7m
#----------------------------
# 历史
$ kubectl rollout history deployment nginx-deployment
deployments "nginx-deployment"
REVISION  CHANGE-CAUSE
1         <none>
2         <none>
#----------------------------
# 回滚
$ kubectl rollout undo deployment nginx-deployment
deployment "nginx-deployment"
$ kubectl get deployment -o wide
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE       CONTAINERS   IMAGES         SELECTOR
nginx-deployment   3         3         3            3           20m       nginx        nginx:1.12.2   app=nginx

Service

port simple example

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# 创建
kubectl expose deployment nginx-deployment --type=NodePort
# --------------------
# 监听了 minikube 的端口 32117
kubectl get svc
NAME               TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes         ClusterIP   10.96.0.1        <none>        443/TCP        1h
nginx-deployment   NodePort    10.102.175.227   <none>        80:32117/TCP   18s

对外服务的三种方式（端口）

  • kubectl expose
  • yaml文件定义service
    • ClusterIP（外界无法访问）
    • NodePort（绑定到Node，对外提供访问的）
    • LoadBalancer（云服务商提供）
  • DNS

ClusterIP

内部网络

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# ClusterIP
# 创建
kubectl expose deployment service-test
# 单行 shell
while true; do curl 10.3.120.168:80080; done
# 无宕机更新? 这个会有一小段的中断
kubectl edit deployment service-test

Rolling Update todo，task

NodePort

对外提供访问

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# pod_nginx.yml
apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
  labels:
    app: nginx
spec:
  containers:
  - name: nginx-container
    image: nginx
    ports:
    - name: nginx-port
      containerPort: 80
  • example
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# 创建 pod
kubectl create -f pod_nginx.yml
# 创建 NodePort 
kubectl expose pods nginx-pods --type=NodePort
# 查看 node 详细信息
kubectl describe node minikube
# ----------------------------
# 查看 NodePort
$ kubectl get svc
NAME               TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes         ClusterIP   10.96.0.1        <none>        443/TCP        19h
nginx-deployment   NodePort    10.102.175.227   <none>        80:32117/TCP   17h
# ---------------------------
$ kubectl get node
NAME       STATUS    ROLES     AGE       VERSION
minikube   Ready     master    19h       v1.10.0

通过yaml文件创建service

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# service_nginx.yml
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  ports:
  - port: 33333 # 8080
    nodePort: 32333 # 8080
    targetPort: nginx-port
    protocol: TCP
  selector: # 过滤 选择暴露哪个 pod
    app: nginx
  type: NodePort
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# lables
$ kubectl get pods --show-labels
NAME        READY     STATUS    RESTARTS   AGE       LABELS
nginx-pod   1/1       Running   0          41m       app=nginx

lable

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# 先创建 pod
kubectl create -f 
# 设置lable
bukectl label node minikube hardware=good
# -------------------------------
# 执行前
$ kubectl get pods
NAME          READY     STATUS    RESTARTS   AGE
busybox-pod   0/1       Pending   0          16s
nginx-pod     1/1       Running   0          1h
# -----------------------------
# 执行后
$ kubectl get pods
NAME          READY     STATUS    RESTARTS   AGE
busybox-pod   1/1       Running   0          1m
nginx-pod     1/1       Running   0          1h
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# pod_busybox.yml
# 创建之后它会是 pending
# 它会寻找 lable 是 hardware: good 节点来运行
apiVersion: v1
kind: Pod
metadata:
  name: busybox-pod
  labels:
    app: busybox
spec:
  nodeSelector:
   hardware: good
  containers:
  - name: busybox-container
    image: busybox
    command:
      - sleep
      - "360000"

生产环境一般不用ClusterIP、NodePort，而是LoadBalance、ExternalName。

LoadBalance

external-dns