docker学习笔记(k8s)

缺乏、安全感 2022-07-12 08:57 212阅读 0赞

### 目录 ###

--------------------

1、基本概念
    2、安装使用
    3、常用命令

### k8s基本概念 ###

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Kubernetes 是Google开源的容器集群管理系统，基于Docker构建一个容器的调度服务，提供资源调度、均衡容灾、服务注册、动态扩缩容等功能套件，目前最新版本为1.0.6;

下面是一张简单的架构图

![helloWord.png][]

几个重要概念：

*  Pod : 在Kubernetes系统中，调度的最小颗粒不是单纯的容器，而是抽象成一个Pod，Pod是一个可以被创建、销毁、调度、管理的最小的部署单元。比如一个或一组容器。
 *  Service :Services是真实应用服务的抽象，每一个服务后面都有很多对应的容器来支持，通过Proxy的port和服务selector决定服务请求传递给后端提供服务的容器，对外表现为一个单一访问接口，外部不需要了解后端如何运行，这给扩展或维护后端带来很大的好处。使用nat作为端口转发；
 *  Replication Controllers:Replication Controller确保任何时候Kubernetes集群中有指定数量的pod副本(replicas)在运行， 如果少于指定数量的pod副本(replicas)，Replication Controller会启动新的Container，反之会杀死多余的以保证数量不变。
 *  Labels:Labels是用于区分Pod、Service、Replication Controller的key/value键值对，Pod、Service、 Replication Controller可以有多个label，但是每个label的key只能对应一个value。Labels是Service和Replication Controller运行的基础，他们正是通过labels来选择正确的容器。
 *  Cluster : Cluster是安装在物理机或者是虚拟机上用来运行应用的应用的组件；
 *  Node : 运行了Kubernetes的Cluster机器被成为节点；

### 安装使用 ###

--------------------

master上安装kubernetes

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vim /etc/yum.repos.d/virt7-testing.repo
    
    [virt7-testing]
    name=virt7-testing
    baseurl=http://cbs.centos.org/repos/virt7-testing/x86_64/os/
    gpgcheck=0
    
    
    #注意；这里etcd使用的是yum中的版本；版本号为2.1.1；
    @使用最新版本时测试不通过；
    yum -y install etcd kubernetes
    
    #修改如下文件
    cat vim /etc/kubernetes/config  
    
    [root@h0022062 bin]# cat /etc/kubernetes/config
    ###
    # kubernetes system config
    #
    # The following values are used to configure various aspects of all
    # kubernetes services, including
    #
    #   kube-apiserver.service
    #   kube-controller-manager.service
    #   kube-scheduler.service
    #   kubelet.service
    #   kube-proxy.service
    # logging to stderr means we get it in the systemd journal
    KUBE_LOGTOSTDERR="--logtostderr=true"
    
    # journal message level, 0 is debug
    KUBE_LOG_LEVEL="--v=0"
    
    # Should this cluster be allowed to run privileged docker containers
    KUBE_ALLOW_PRIV="--allow_privileged=false"
    
    # How the controller-manager, scheduler, and proxy find the apiserver
    #KUBE_MASTER="--master=http://127.0.0.1:8080"
    
    KUBE_ETCD_SERVERS="--etcd_servers=http://locate:2379"
    
    
    [root@h0022062 bin]# cat /etc/kubernetes/apiserver
    ###
    # kubernetes system config
    #
    # The following values are used to configure the kube-apiserver
    #
    
    # The address on the local server to listen to.
    KUBE_API_ADDRESS="--address=0.0.0.0"
    
    # The port on the local server to listen on.
    KUBE_API_PORT="--port=8080"
    
    # Port minions listen on
    KUBELET_PORT="--kubelet_port=10250"
    
    # How the replication controller and scheduler find the kube-apiserver
    KUBE_MASTER="--master=http://centos-master:8080"
    
    # Comma separated list of nodes in the etcd cluster
    KUBE_ETCD_SERVERS="--etcd_servers=http://localhost:2379"
    
    # Address range to use for services
    KUBE_SERVICE_ADDRESSES="--service-cluster-ip-range=10.254.0.0/16"
    
    # default admission control policies
    #KUBE_ADMISSION_CONTROL="--admission_control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ServiceAccount,ResourceQuota"
    
    # Add your own!
    KUBE_API_ARGS=""
    
    #启动服务；
    service etcd start
    service kube-apiserver start
    service kube-controller-manager start
    service kube-scheduler start

master上启动节点；

--------------------

#修改配置文件
    [root@h0022062 server]# cat /etc/kubernetes/kubelet
    ###
    # kubernetes kubelet (minion) config
    
    # The address for the info server to serve on (set to 0.0.0.0 or "" for all interfaces)
    KUBELET_ADDRESS="--address=127.0.0.1"
    
    # The port for the info server to serve on
    KUBELET_PORT="--port=10250"
    
    # You may leave this blank to use the actual hostname
    KUBELET_HOSTNAME="--hostname_override=127.0.0.1"
    
    # location of the api-server
    KUBELET_API_SERVER="--api_servers=http://127.0.0.1:8080"
    
    # Add your own!
    KUBELET_ARGS=""
    
    #启动各个节点；
    service kube-proxy start
    service kubelet start
    service docker start

Offline

--------------------

在Kubernetes启动pod的时候；会尝试下载一些镜像；由于网络问题；这些镜像一般下载不了； 需要事先下载好；以便测试；

docker pull gcr.io/google_containers/pause
    docker pull gcr.io/google_containers/pause:0.8.0
    docker tag gcr.io/google_containers/pause docker.io/kubernetes/pause

HelloWord

--------------------

#创建pod；
    [root@h0022062 server]# kubectl run my-nginx --image=127.0.0.1:5010/centos-nginx --replicas=2 --port=80
    CONTROLLER   CONTAINER(S)   IMAGE(S)                      SELECTOR       REPLICAS
    my-nginx     my-nginx       127.0.0.1:5010/centos-nginx   run=my-nginx   2
    [root@h0022062 server]# 
    [root@h0022062 server]# 
    #查看已经存在的pod
    [root@h0022062 server]# kubectl get pods
    NAME             READY     STATUS    RESTARTS   AGE
    my-nginx-bnmhj   1/1       Running   0          11s
    my-nginx-lqkny   1/1       Running   0          11s
    
    #查看replicationcontroller
    [root@h0022062 bin]# kubectl get replicationcontroller
    CONTROLLER   CONTAINER(S)   IMAGE(S)   SELECTOR       REPLICAS
    my-nginx     my-nginx       nginx      run=my-nginx   2
    
    #停止pods
    [root@h0022062 server]# kubectl stop replicationcontroller my-nginx
    replicationcontrollers/my-nginx
    #确认是否停止成功
    [root@h0022062 server]# kubectl get pods
    NAME      READY     STATUS    RESTARTS   AGE

HelloWord-实际可以访问的service

--------------------

[root@h0022062 server]# kubectl get pods
    NAME      READY     STATUS    RESTARTS   AGE
    [root@h0022062 server]# kubectl get services
    NAME         LABELS                                    SELECTOR   IP(S)         PORT(S)
    kubernetes   component=apiserver,provider=kubernetes   <none>     192.168.0.1   443/TCP
    
    [root@h0022062 server]# cat pod.yaml 
    apiVersion: v1
    kind: ReplicationController
    metadata:
      name: mynginx
      labels:
        name: mynginx
    spec:
      replicas: 2
      template:
        metadata:
          labels:
            app: nginx
        spec:
          containers:
          - name: mynginx
            image: 127.0.0.1:5010/centos-nginx
            ports:
            - containerPort: 80
    
    [root@h0022062 server]# kubectl create -f pod.yaml 
    replicationcontrollers/mynginx
    [root@h0022062 server]# kubectl get pods
    NAME            READY     STATUS    RESTARTS   AGE
    mynginx-3sz2i   1/1       Running   0          1m
    mynginx-m821h   1/1       Running   0          1m
    
    #添加服务
    [root@h0022062 server]# cat service.json 
    {
        "kind": "Service",
        "apiVersion": "v1",
        "metadata": {
            "name": "my-service"
        },
        "spec": {
            "selector": {
                "app": "nginx"
            },
            "ports": [
                {
                    "protocol": "TCP",
                    "port": 80,
                    "targetPort": 80
                }
            ]
        }
    }
    
    #启动服务
    [root@h0022062 server]# kubectl create -f service.json 
    
    #iptables查看nat的映射表
    [root@h0022062 server]# iptables -nvL -t nat
    7   420 DNAT       tcp  --  *      *       0.0.0.0/0            10.254.79.222        /* default/my-service: */ tcp dpt:80 to:192.168.77.114:13412
    
    #访问测试；

![helloWord.png][helloWord.png 1]

#
    [root@h0022062 server]# kubectl stop -f pod.yaml 
    pods/mynginx
    
    #有一个pending；可以使用describe命令查看详情
    [root@h0022062 server]# kubectl describe pods/mynginx-3sz2i

### 常用命令 ###

--------------------

kubectl create

作用：通过文件创建资源（pod、Replication Controllers、Service）等；支持YAML和JSON格式； 示例：

kubectl create -f ./pod.json

kubectl get

作用：列出资源列表； 示例：

// 显示所有的pods
    $ kubectl get pods
    
    //显示replicationcontroller
    $ kubectl get replicationcontroller
    $ kubectl get rc
    
    //显示service
    $ kubectl get service
    
    //显示所有节点
    $ kubectl get node
    
    // 显示pod web-pod-13je7 的json
    $ kubectl get -o json pod web-pod-13je7
    
    // List one or more resources by their type and names.
    $ kubectl get rc/web service/frontend pods/web-pod-13je7

kubectl delete

作用：删除资源；可以使用文件或者是标签来标记删除的资源； 示例：

// Delete a pod using the type and name specified in pod.json.
    $ kubectl delete -f ./pod.json
    
    // Delete pods and services with label name=myLabel.
    $ kubectl delete pods,services -l name=myLabel
    
    // Delete all pods
    $ kubectl delete pods --all

kubectl describe

作用：显示资源的详情；可以用于显示pending状态

示例：

// 显示nodes名称为kubernetes-minion-emt8.c.myproject.internal的详情
    $ kubectl describe nodes kubernetes-minion-emt8.c.myproject.internal
    
    //显示pods名称为nginx的详情
    $ kubectl describe pods/nginx
    
    // 显示标签为 name=myLabel 的pods
    $ kubectl describe po -l name=myLabel

kubectl logs

作用：显示pod内容器的日志；

示例：

#如果是pod内只有一个容器；容器名称可选
     kubectl logs mynginx-24aw5
     kubectl logs mynginx-24aw5 mynginx

kubectl stop

作用：停止一个资源；

示例：

// Shut down foo.
    $ kubectl stop replicationcontroller foo
    
    // Stop pods and services with label name=myLabel.
    $ kubectl stop pods,services -l name=myLabel
    
    // Shut down the service defined in service.json
    $ kubectl stop -f service.json
    
    // Shut down all resources in the path/to/resources directory
    $ kubectl stop -f path/to/resources

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[helloWord.png]: http://violetgo.com/files/image/k8s/k8s.png
[helloWord.png 1]: http://violetgo.com/files/image/k8s/helloWord.png
[70]: /images/20220710/fe95de02d43c4f19bd0a768ec0fa7a12.png