docker学习笔记(k8s)-蒲公英云

k8s基本概念

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

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

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；

#
[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