k8s中文文档

• k8s概念比较多，有什么概念的疑惑的推荐看k8s中文文档。

me的环境

• 操作系统：centos7
• docker：1.12.6

环境跟me的不一致？不要慌，基本大部分操作都是行的通的。

还慌？那就直接用网页在线版的kubernets吧

kubernets单机版安装部署

kubernetes部署算是有一定门槛的。为了不从入门到放弃，推荐一开始安装单机版作为入门熟悉kubectl指令、了解工作原理。

• 安装流程，切换成root

  1.关闭centos自带的防火墙# systemctl disable firewalld# systemctl stop firewalld 2.安装etcd和kubernetes软件（会自动安装docker）# yum install -y etcd kubernetes
  

• 修改两处配置

  1. Docker配置文件/etc/sysconfig/docker, OPTIONS=’–selinux-enabled=false –insecure-registry gcr.io’

  

  1. Kubernetes apiservce配置文件/etc/kubernetes/apiserver,把–admission_control参数钟的ServiceAccount删除

  

启动所有服务

# systemctl start etcd
# systemctl start docker
# systemctl start kube-apiserver
# systemctl start kube-controller-manager
# systemctl start kube-scheduler
# systemctl start kubelet
# systemctl start kube-proxy

初入门小实例

• 部署nginx服务

  $ kubectl run my-nginx --image=nginx --port=80
  $ kubectl get pod  # 查看pod

  发现pod状态无论多久都是处于pending。READY字段一直是0/1,服务部署失败的原因是”中国墙“的问题导致无法下载pod启动时需要的谷歌镜像，所以我们得间接的创建所需的镜像。

  补充： Pending状态表示API Server已经创建Pod，但Pod内还有一个或者多个容器没有创建，或者正在下载镜像的过程。详细的参考Pod声明周期和重启策略

• 创建gcr.io/google_containers/pause-amd64:3.0镜像

  $ docker pull googlecontainer/pause-amd64:3.0
  $ docker tag googlecontainer/pause-amd64:3.0 gcr.io/google_containers/pause-amd64:3.0

  ​

kubernets指令

• 实例流程

# 查看版本
$ kubectl  version
Client Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2", GitCommit:"269f928217957e7126dc87e6adfa82242bfe5b1e", GitTreeState:"clean", BuildDate:"2017-07-03T15:31:10Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2", GitCommit:"269f928217957e7126dc87e6adfa82242bfe5b1e", GitTreeState:"clean", BuildDate:"2017-07-03T15:31:10Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}# 显示集群信息
$ kubectl cluster-info
Kubernetes master is running at http://localhost:8080
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.# 查看集群中有几个Node
$ kubectl get nodes
NAME        STATUS    AGE
127.0.0.1   Ready     18h# 运行一个镜像
$ kubectl run my-nginx --image=nginx --replicas=2 --port=80
deployment "my-nginx" created# 查看pod
$ kubectl  get pods
NAME                       READY     STATUS              RESTARTS   AGE
my-nginx-379829228-cwlbb   0/1       ContainerCreating   0          20s
my-nginx-379829228-czk6w   1/1       Running             0          20s# 查看服务详情信息
$ kubectl  describe pod my-nginx-379829228-cwlbb# 查看已部署
$ kubectl  get deployments
NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
my-nginx   2         2         2            2           3m# 删除pod
$ kubectl delete pod my-nginx-379829228-cwlbb
pod "my-nginx-379829228-cwlbb" deleted# 再次查看pod，发现由于replicas机制，pod又生成一个新的
$ kubectl  get pods
NAME                       READY     STATUS              RESTARTS   AGE
my-nginx-379829228-czk6w   1/1       Running             0          11m
my-nginx-379829228-gjd7d   0/1       ContainerCreating   0          5s# 删除部署的my-nginx服务。彻底删除pod
$ kubectl delete deployment my-nginx
deployment "my-nginx" deleted

对比docker命令

k8s的学习路线基本都是从docker[容器]到k8s的，因此两个对比理解有助于记忆

# docker run
$ docker run -d -e DOMAIN=cluster --name my-nginx -p 80:80 nginx
$ kubectl run my-nginx --image=nginx --port=80 --env="DOMAIN=cluster"# docker ps 
$ docker ps 
$ kubectl get pods# docker exec
$ docker exec [容器id] ls
$ kubectl exec [pod_id] ls# docker exec 交互式
$ docker exec -it [容器id] /bin/sh
$ kubectl exec -it [pod_id] -- /bin/sh# docker info
$ docker info 
$ kubectl cluster-info

重要名词

名词	翻译
Namespace	命名空间
Endpoint	服务端点
Controller Manager	管理控制中心
Replication	副本控制器

yaml文件管理服务

• 用yaml文件来创建服务

  
  # vi nginx.yamlpiVersion: extensions/v1beta1
  kind: Deployment
  metadata:
  name: my-nginx
  spec:
  replicas: 3
  template:metadata:labels:app: nginxspec:containers:- name: nginximage: nginx:1.7.9ports:- containerPort: 80

• 启动管理服务

  
  # 根据yaml文件创建服务$ kubectl create -f nginx.yaml 
  deployment "my-nginx" created# 查看deployment$ kubectl get deployments
  NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
  my-nginx   3         3         3            3           6s# 查看Pod$ kubectl get pod
  NAME                        READY     STATUS    RESTARTS   AGE
  my-nginx-4087004473-dtrjp   1/1       Running   0          7s
  my-nginx-4087004473-jz80p   1/1       Running   0          7s
  my-nginx-4087004473-wh576   1/1       Running   0          7s# 根据yaml文件删除服务$ kubectl delete -f nginx.yaml 
  deployment "my-nginx" deleted$ kubectl get pod
  No resources found.
  $ kubectl get deployment
  No resources found.

  ​

  ​

Service

• 到此，我们部署一个nginx服务

  $ kubectl run my-nginx --image=nginx --port=80# 创建一个service 且将其暴露到集群外可供访问$ kubectl expose deployment/my-nginx --type="NodePort" --port 80
  service "my-nginx" exposed# 此时service列表多个my-nginx服务$ kubectl get services
  NAME         CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
  kubernetes   10.254.0.1       <none>        443/TCP        7d
  my-nginx     10.254.255.103   <nodes>       80:32589/TCP   7s

  宿主主机内访问该服务

  

  同网段的机器访问该服务

  

deployments

# 运行nginx镜像
$ kubectl run my-nginx --image=nginx --port=80
# 交互式 shell 的方式运行 pod
$ kubectl run -i --tty my-nginx --image=nginx --port=80 -- sh
# 链接到运行中的容器
$ kubectl attach my-nginx-532658988-10kxd -i# 查看deployment
$ kubectl get deployments
NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
my-nginx   1         1         1            1           25m
# 扩展10个副本
$ kubectl scale deployment my-nginx --replicas=10
deployment "my-nginx" scaled
$ kubectl scale  deployment/my-nginx --replicas=10 # 作用效果等同上一条命令 
deployment "my-nginx" scaled
# 再次显示deployment
$ kubectl get deployments
NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
my-nginx   10        10        10           1           26m
$ kubectl get pods
NAME                       READY     STATUS    RESTARTS   AGE
my-nginx-379829228-38hkg   1/1       Running   0          5m
my-nginx-379829228-7j15l   1/1       Running   0          31m
my-nginx-379829228-c8mt3   1/1       Running   0          5m
my-nginx-379829228-f6mm8   1/1       Running   0          5m
my-nginx-379829228-q1rj0   1/1       Running   0          5m
my-nginx-379829228-qg7lf   1/1       Running   0          5m
my-nginx-379829228-rjfbq   1/1       Running   0          5m
my-nginx-379829228-v581r   1/1       Running   0          5m
my-nginx-379829228-wh49w   1/1       Running   0          5m
my-nginx-379829228-wpn98   1/1       Running   0          5m# 缩扩到1个副本
$ kubectl scale  deployment/my-nginx --replicas=1
deployment "my-nginx" scaled
$ kubectl scale deployment my-nginx --replicas=1   # 作用效果等同上一条命令

deployment的更新回滚

$ kubectl create -f nginx.yaml
$ kubectl get pod
NAME                        READY     STATUS    RESTARTS   AGE
my-nginx-4087004473-4xj74   1/1       Running   0          3m
my-nginx-4087004473-jkptq   1/1       Running   0          3m
my-nginx-4087004473-m55s1   1/1       Running   0          3m
$ kubectl get deployment
NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
my-nginx   3         3         3            3           4m
# 更新应用的镜像从1.7.9版本——>1.9.1
$ kubectl set image deployment/my-nginx nginx=nginx:1.9.1
deployment "my-nginx" image updated
# 确认是否更新成功
$ kubectl rollout status deployment/my-nginx
deployment "my-nginx" successfully rolled out
# 回滚到上一代版本
$ kubectl rollout undo deployment/my-nginx
deployment "my-nginx" rolled back

ConfigMap-容器应用的配置管理

应用部署的一个最佳实践是将应用所需配置信息和程序进行分离，一则程序可以更好的复用，二则能灵活的更改配置从而实现其他功能。

使用configMap替代环境变量

以yaml文件方式创建ConfigMap

# vi special-config.yamlapiVersion: v1
kind: ConfigMap
metadata:name: special-confignamespace: default
data:special.how: veryspecial.type: charm

# vi env-config.yamlapiVersion: v1
kind: ConfigMap
metadata:name: env-confignamespace: default
data:log_level: INFO

可以在Pod中这样使用ConfigMap

# vi configMap.yamlapiVersion: v1
kind: Pod
metadata:name: dapi-test-pod
spec:containers:- name: test-containerimage: nginxcommand: [ "/bin/sh", "-c", "env" ]env:- name: SPECIAL_LEVEL_KEY   #定义环境变量名称valueFrom:       #key"special.how"对应的值configMapKeyRef:name: special-config #环境变量的值key: special.how- name: SPECIAL_TYPE_KEYvalueFrom:configMapKeyRef:name: special-configkey: special.typerestartPolicy: Never

启动等一系列操作

$ kubectl create -f special-config.yaml
configmap "special-config" created
$ kubectl create -f env-config.yaml
configmap "env-config" created
# 查看ConfigMap
$ kubectl get configmaps
NAME             DATA      AGE
env-config       1         38m
special-config   2         39m
# 让我们看一下创建的ConfigMap
$  kubectl describe configmap env-config
Name:       env-config
Namespace:  default
Labels:     <none>
Annotations:    <none>Data
====
log_level:  4 bytes# 查看ConfigMap键的值
$ kubectl get configmaps env-config -o yaml
apiVersion: v1
data:log_level: INFO
kind: ConfigMap
metadata:creationTimestamp: 2017-11-30T07:29:49Zname: env-confignamespace: defaultresourceVersion: "285268"selfLink: /api/v1/namespaces/default/configmaps/env-configuid: 3f473adf-d5a0-11e7-9830-0800275ae9e7

​

$ kubectl create -f configMap.yaml
pod "dapi-test-pod" created
# 查看pod，状态ContainerCreating
$ kubectl get pod
NAME            READY     STATUS              RESTARTS   AGE
dapi-test-pod   0/1       ContainerCreating   0          3s
# 隔一段时间再查看pod,发现并没有返回什么
$  kubectl get pod
# 显示所有的权限查看pod
$ kubectl get pod --show-all
NAME            READY     STATUS      RESTARTS   AGE
dapi-test-pod   0/1       Completed   0          1m
# 查看详情
$ kubectl describe pod dapi-test-pod
Name:       dapi-test-pod
Namespace:  default
Node:       127.0.0.1/127.0.0.1
Start Time: Thu, 30 Nov 2017 15:32:00 +0800
Labels:     <none>
Status:     Succeeded
IP:     
Controllers:    <none>
Containers:test-container:Container ID:   docker://1ba533f43ee60c02e03dafb7bcb8495fc12264aaab229872df0b289a3c1b9976Image:      nginxImage ID:       docker-pullable://docker.io/nginx@sha256:b81f317384d7388708a498555c28a7cce778a8f291d90021208b3eba3fe74887Port:       Command:/bin/sh-cenvState:      TerminatedReason:       CompletedExit Code:    0Started:      Thu, 30 Nov 2017 15:32:25 +0800Finished:     Thu, 30 Nov 2017 15:32:25 +0800Ready:      FalseRestart Count:  0Volume Mounts:  <none>Environment Variables:SPECIAL_LEVEL_KEY:    <set to the key 'special.how' of config map 'special-config'>SPECIAL_TYPE_KEY:     <set to the key 'special.type' of config map 'special-config'>
Conditions:Type      StatusInitialized   True Ready     False PodScheduled  True 
No volumes.
QoS Class:  BestEffort
Tolerations:    <none>
Events:FirstSeen LastSeen    Count   From            SubObjectPath           Type        Reason          Message--------- --------    -----   ----            -------------           --------    ------          -------3m        3m      1   {default-scheduler }                    Normal      Scheduled       Successfully assigned dapi-test-pod to 127.0.0.13m        3m      1   {kubelet 127.0.0.1} spec.containers{test-container} Normal      Pulling         pulling image "nginx"3m        2m      2   {kubelet 127.0.0.1}                 Warning     MissingClusterDNS   kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.2m        2m      1   {kubelet 127.0.0.1} spec.containers{test-container} Normal      Pulled          Successfully pulled image "nginx"2m        2m      1   {kubelet 127.0.0.1} spec.containers{test-container} Normal      Created         Created container with docker id 1ba533f43ee6; Security:[seccomp=unconfined]2m        2m      1   {kubelet 127.0.0.1} spec.containers{test-container} Normal      Started         Started container with docker id 1ba533f43ee6
# 可知container started 成功，进一步查看日志
$ docker logs 1ba
KUBERNETES_SERVICE_PORT=443
KUBERNETES_PORT=tcp://10.254.0.1:443
MY_SERVICE_PORT_80_TCP=tcp://10.254.110.249:80
MY_SERVICE_PORT_443_TCP_ADDR=10.254.110.249
HOSTNAME=dapi-test-pod
MY_SERVICE_PORT_443_TCP_PORT=443
HOME=/root
MY_SERVICE_PORT_443_TCP_PROTO=tcp
MY_SERVICE_SERVICE_PORT_HTTP=80
SPECIAL_TYPE_KEY=charm
MY_SERVICE_SERVICE_PORT_HTTPS=443
MY_SERVICE_PORT_443_TCP=tcp://10.254.110.249:443
MY_SERVICE_SERVICE_HOST=10.254.110.249
KUBERNETES_PORT_443_TCP_ADDR=10.254.0.1
NGINX_VERSION=1.13.7-1~stretch
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
KUBERNETES_PORT_443_TCP_PORT=443
NJS_VERSION=1.13.7.0.1.15-1~stretch
KUBERNETES_PORT_443_TCP_PROTO=tcp
MY_SERVICE_SERVICE_PORT=80
MY_SERVICE_PORT=tcp://10.254.110.249:80
SPECIAL_LEVEL_KEY=very
MY_SERVICE_PORT_80_TCP_ADDR=10.254.110.249
KUBERNETES_PORT_443_TCP=tcp://10.254.0.1:443
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_SERVICE_HOST=10.254.0.1
MY_SERVICE_PORT_80_TCP_PORT=80
PWD=/
MY_SERVICE_PORT_80_TCP_PROTO=tcp

​

ConfigMap的限制条件

• ConfigMap必须在Pod之前创建才能被使用。
• ConfigMap可以定义其属于哪个Namspece，只有在同一个Namespace中的pod才能引用。

删除Pod

• 有时候deployment、rs、rc、services都为0，但是Pod确存在着。则重启kubelet服务即可。

$ systemctl restart kubelet

补充

# 列出当前节点名
kubectl get node
NAME        STATUS    AGE
127.0.0.1   Ready     6d
# 已知当前节点名为127.0.0.1,用如下命令即可获得该节点上所有运行节点
$ curl localhost:8080/api/v1/proxy/nodes/127.0.0.1/pods
{"kind":"PodList","apiVersion":"v1","metadata":{},"items":null}

我们最好不要越过RC而直接创建Pod,因为Replication Controller会通过RC管理Pod副本。实现自动创建、补足、替换、删除Pod副本，大大提高系统的容灾能力

• 重新调度(Rescheduling)
• 弹性伸缩(Scaling)
• 滚动更新(Rolling Updates)

---

报错

$ sudo kubectl create -f file.yaml
YAML error: found character that cannot start any token 
# or
error:yaml: line 15: found a tab character that violate indentation#file.yaml不可用tab键来空格