基于kubernetes 1.0.6 构建Docker集群管理

wcm · 发表于 2015-10-22 11:05:28

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。本文介绍如何基于Centos7构建Kubernetes平台。

centos 7.1.1503 + etcd 2.2.0 + kubernetes 1.0.6 + docker 1.7.1

一、环境安装

1.etcd安装(可独立安装)

[root@docker3 ~]# wget https://github.com/coreos/etcd/releases/download/v2.2.0/etcd-v2.2.0-linux-amd64.tar.gz  
[root@docker3 ~]# tar -zxvf etcd-v2.2.0-linux-amd64.tar.gz  
[root@docker3 ~]# cd etcd-v2.2.0-linux-amd64  
[root@docker3 ~]# cp etcd* /usr/local/bin/
[root@docker3 ~]# etcd -peer-bind-addr 0.0.0.0:2380 -bind-addr 0.0.0.0:2379 &

2.kubernetes安装(master)

[root@docker3 ~]# yum -y install kubernetes

kubernetes升级至v1.0.6，覆盖bin文件即可，方法如下：

[root@docker3 ~]# wget https://github.com/GoogleCloudPlatform/kubernetes/releases/download/v1.0.6/kubernetes.tar.gz
[root@docker3 ~]# tar zxf kubernetes.tar.gz
[root@docker3 ~]# tar zxf kubernetes/server/kubernetes-server-linux-amd64.tar.gz
[root@docker3 ~]# cp kubernetes/server/bin/kube* /usr/bin

3.配置master侧kubernetes相关文件

[root@docker3 ~]# 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://192.168.0.5:8080"

kubernetes apiserver文件

[root@docker3 ~]# 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"

# Comma separated list of nodes in the etcd cluster
KUBE_ETCD_SERVERS="--etcd_servers=http://192.168.0.5:2379"

# 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=""

kubernetes controller-manager文件

[root@docker3 ~]# cat /etc/kubernetes/controller-manager
###
# The following values are used to configure the kubernetes controller-manager
KUBELET_ADDRESSES="--machines= 192.168.0.5"

# defaults from config and apiserver should be adequate

# Add your own!
KUBE_CONTROLLER_MANAGER_ARGS=""

4.启动master侧相关服务

[root@docker3 ~]# systemctl start kube-apiserver.service kube-controller-manager.service kube-scheduler.service
[root@docker3 ~]# systemctl enable kube-apiserver.service kube-controller-manager.service kube-scheduler.service
[root@docker3 ~]# kubectl version
Client Version: version.Info{Major:"1", Minor:"0", GitVersion:"v1.0.6", GitCommit:"388061f00f0d9e4d641f9ed4971c775e1654579d", GitTreeState:"clean"}
Server Version: version.Info{Major:"1", Minor:"0", GitVersion:"v1.0.6", GitCommit:"388061f00f0d9e4d641f9ed4971c775e1654579d", GitTreeState:"clean"}

5.kubernetes安装(nodes)

[root@docker3 ~]# yum -y install kubernetes docker
注：如果不做多节点测试，仅安装docker即可

6.配置slave侧kubernetes kubelet文件

[root@docker3 ~]# 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=0.0.0.0"

# 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=192.168.0.5"

# location of the api-server
KUBELET_API_SERVER="--api_servers=http://192.168.0.5:8080"

# Add your own!
KUBELET_ARGS=""

7.启动node侧相关服务

[root@docker3 ~]# systemctl enable docker.service kubelet.service kube-proxy.service
[root@docker3 ~]# systemctl start docker.service kubelet.service kube-proxy.service

8.查看nodes

[root@docker3 ~]# kubectl get nodes
NAME          LABELS                               STATUS
192.168.0.5   kubernetes.io/hostname=192.168.0.5   Ready

这样安装就ok了。如果查看nodes为空，请检查以上步骤是否配置正确。

9.创建测试pod单元

[root@docker3 ~]# cat apache-pod.yaml
apiVersion: v1
kind: Pod
metadata:
 name: apache
spec:
 containers:
 - name: apache
 image: docker.io/fedora/apache
 ports:
 - containerPort: 80
 hostPort: 8888

[root@docker3 ~]# kubectl create -f apache-pod.yaml

理论上，这样就ok了。

但是！！！！因为有伟大的GFW！！我们会在slave上看到大体如下的Error：

HTTP Error: statusCode=404 No such image: gcr.io/google_containers/pause:0.8.0

解决方案如下,在slave上运行命令：

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

查看pod单元

[root@docker3 ~]# kubectl get pod
NAME      READY     STATUS    RESTARTS   AGE
apache    0/1       Running   0          8s

打开浏览器，访问http://192.168.0.5:8888/

二、实战操作：通过Kubernetes创建一个webserver集群，以及观察其负载均衡

创建一个replication

[root@docker3 ~]# cat webserver-repl.yaml
apiVersion: v1
kind: ReplicationController
metadata:
 name: webserver
spec:
 replicas: 2
 selector:
 app: webserver
 template:
 metadata:
 labels:
 app: webserver
 spec:
 containers:
 - name: webserver
 image: docker.io/yorko/webserver
 command: ["/bin/sh", "-c", "/usr/bin/supervisord -c /etc/supervisord.conf"]
 ports:
 - containerPort: 80

[root@docker3 ~]#  kubectl create -f webserver-repl.yaml
[root@docker3 ~]# kubectl get pod
NAME              READY     STATUS    RESTARTS   AGE
apache            1/1       Running   0          16m
webserver-51vo1   1/1       Running   0          11s
webserver-xeh61   1/1       Running   0          11s

创建一个service,关联replication selector

[root@docker3 ~]# cat webserver-service.yaml
apiVersion: v1
kind: Service
metadata:
 name: webserver
spec:
 ports:
 - port: 8008
 targetPort: 80
 protocol: TCP
 selector:
 app: webserver

[root@docker3 ~]# kubectl create -f webserver-service.yaml
[root@docker3 ~]# kubectl get service
NAME         LABELS                                    SELECTOR        IP(S)           PORT(S)
kubernetes   component=apiserver,provider=kubernetes   <none>          10.254.0.1      443/TCP
webserver    <none>                                    app=webserver   10.254.69.214   8008/TCP

查询生成的iptables转发规则

[root@docker3 ~]# iptables -nL -t nat|tail -1
DNAT       tcp  --  0.0.0.0/0            10.254.69.214        /* default/webserver: */ tcp dpt:8008 to:192.168.0.5:44893

打开浏览器，访问http://192.168.0.5:44893/info.php

刷新浏览器发现proxy后端的变化，默认为随机轮循算法。

三、测试pods自动复制、销毁，观察kubernetes自动保持2个副本

删除一个replication副本

[root@docker3 ~]# kubectl delete pod webserver-51vo1

自动生成出一个副本，始终保持2份

[root@docker3 ~]# kubectl get pod
NAME              READY     STATUS    RESTARTS   AGE
apache            1/1       Running   0          54m
webserver-xeh61   1/1       Running   0          38m
webserver-yn8au   0/1       Pending   0          2s

[root@docker3 ~]# kubectl get pod
NAME              READY     STATUS    RESTARTS   AGE
apache            1/1       Running   0          54m
webserver-xeh61   1/1       Running   0          38m
webserver-yn8au   1/1       Running   0          11s

这样测试就全部ok了。至于前面是否加一层haproxy/nginx反向代理，随你。。。

参考文献：

http://blog.liuts.com/post/247/

http://segmentfault.com/a/1190000002886795

https://github.com/kubernetes/kubernetes/blob/master/docs/user-guide/walkthrough/k8s201.md

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基于kubernetes 1.0.6 构建Docker集群管理

一、环境安装

二、实战操作：通过Kubernetes创建一个webserver集群，以及观察其负载均衡

三、测试pods自动复制、销毁，观察kubernetes自动保持2个副本