linux

在centos7上安装和配置Kubernetes集群管理pods和services

安装前准备

操作系统详情

需要三台主机，都最小化安装 centos7.1,并update到最新，详情见如下表格

角色 主机名 IP
Master master 192.168.0.79
Minion1 minion-1 192.168.0.80
Minion2 minion-2 192.168.0.81

在每台主机上关闭firewalld改用iptables

输入以下命令，关闭firewalld

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# systemctl stop firewalld.service    #停止firewall
# systemctl disable firewalld.service #禁止firewall开机启动

然后安装iptables并启用

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# yum install -y iptables-services     #安装
# systemctl start iptables.service  #最后重启防火墙使配置生效
# systemctl enable iptables.service #设置防火墙开机启动

安装ntp服务

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# yum install -y ntp
# systemctl start ntpd
# systemctl enable ntpd

安装配置

注：slug:，etcd等已经进入centos epel源，可以直接yum安装（需要安装epel-release）

安装 Kubernetes Master

1. 使用以下命令安装kubernetes 和 etcd

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# yum install -y kubernetes etcd

2. 编辑/etc/etcd/etcd.conf 使etcd监听所有的ip地址，确保下列行没有注释，并修改为下面的值

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# vim /etc/etcd/etcd.conf
# [member]
ETCD_NAME=default
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"
ETCD_LISTEN_CLIENT_URLS="<span style="color: #ff0000;">http://0.0.0.0:2379</span>"
#[cluster]
ETCD_ADVERTISE_CLIENT_URLS="http://localhost:2379"

3. 编辑Kubernetes API server的配置文件

确保下列行没有被注释，并为下列的值

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# vim /etc/slug:/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://127.0.0.1:2379"

# 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=""

4. 启动etcd, kube-apiserver, kube-controller-manager 和 kube-scheduler服务，并设置开机自启

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# for SERVICES in etcd kube-apiserver kube-controller-manager kube-scheduler; do 
    systemctl restart $SERVICES
    systemctl enable $SERVICES
    systemctl status $SERVICES 
done

5. 在etcd中定义flannel network的配置，这些配置会被flannel service下发到minions:

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# etcdctl mk /coreos.com/network/config '{"Network":"172.17.0.0/16"}'

6. 添加iptables规则，允许相应的端口

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iptables -I INPUT -p tcp --dport 2379 -j ACCEPT
iptables -I INPUT -p tcp --dport 10250 -j ACCEPT
iptables -I INPUT -p tcp --dport 8080 -j ACCEPT
iptables-save

7. 查看节点信息（我们还没有配置节点信息，所以这里应该为空）

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# kubectl get nodes
NAME             LABELS              STATUS

安装Kubernetes Minions (Nodes)

注：下面这些步骤应该在minion1和minions2上执行（也可以添加更多的minions）

1. 使用yum安装kubernetes 和 flannel

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# yum install -y flannel kubernetes

2. 为flannel service配置etcd服务器

编辑/etc/sysconfig/flanneld文件中的下列行以连接到master

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# vim /etc/sysconfig/flanneld

FLANNEL_ETCD="http://192.168.0.79:2379"        #改为etcd服务器的ip

3. 编辑 kubernetes 配置文件

编辑/etc/slug:/config中kubernetes的默认配置，确保KUBE_MASTER的值是连接到Kubernetes master API server：

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# vim /etc/slug:/config
KUBE_MASTER="--master=http://192.168.0.79:8080"

4. 编辑/etc/slug:/kubelet 如下行：

minion1:

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# vim /etc/slug:/kubelet

KUBELET_ADDRESS="--address=0.0.0.0"
KUBELET_PORT="--port=10250"
KUBELET_HOSTNAME="--hostname_override=192.168.0.80"
KUBELET_API_SERVER="--api_servers=http://192.168.0.79:8080"
KUBELET_ARGS=""

minion2:

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# vim /etc/slug:/kubelet

KUBELET_ADDRESS="--address=0.0.0.0"
KUBELET_PORT="--port=10250"
KUBELET_HOSTNAME="--hostname_override=192.168.0.81"
KUBELET_API_SERVER="--api_servers=http://192.168.0.79:8080"
KUBELET_ARGS=""

5. 启动kube-proxy, kubelet, docker 和 flanneld services服务，并设置开机自启

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# for SERVICES in kube-proxy kubelet docker flanneld; do 
    systemctl restart $SERVICES
    systemctl enable $SERVICES
    systemctl status $SERVICES 
done

6. 在每个minion节点，你应当注意到你有两块新的网卡docker0 和 flannel0。你应该得到不同的ip地址范围在flannel0上，就像下面这样：

minion1:

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# ip a | grep flannel | grep inet
    inet 172.17.29.0/16 scope global flannel0

minion2:

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# ip a | grep flannel | grep inet
    inet 172.17.37.0/16 scope global flannel0

7. 添加iptables规则：

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iptables -I INPUT -p tcp --dport 2379 -j ACCEPT
iptables -I INPUT -p tcp --dport 10250 -j ACCEPT
iptables -I INPUT -p tcp --dport 8080 -j ACCEPT

8. 现在登陆kubernetes master节点验证minions的节点状态：

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# kubectl get nodes
NAME           LABELS                                STATUS
192.168.0.80   slug:.io/hostname=192.168.0.80   Ready
192.168.0.81   slug:.io/hostname=192.168.0.81   Ready

至此，kubernetes集群已经配置并运行了，我们可以继续下面的步骤。

创建 Pods (Containers)

为了创建一个pod，我们需要在kubernetes master上面定义一个yaml 或者 json配置文件。然后使用kubectl命令创建pod

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# mkdir -p k8s/pods
# cd k8s/pods/
# vim nginx.yaml

在nginx.yaml里面增加如下内容：

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apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 80

创建pod:

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# kubectl create -f nginx.yaml

此时有如下报错：

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Error from server: error when creating "nginx.yaml": Pod "nginx" is forbidden: no API token found for service account default/default, retry after the token is automatically created and added to the service account

解决办法是编辑/etc/slug:/apiserver 去除 KUBE_ADMISSION_CONTROL 中的 SecurityContextDeny,ServiceAccount ，并重启kube-apiserver.service服务：

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# vim /etc/slug:/apiserver
KUBE_ADMISSION_CONTROL="--admission_control=NamespaceLifecycle,NamespaceExists,LimitRanger,ResourceQuota"

# systemctl restart kube-apiserver.service

之后重新创建pod:

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# kubectl create -f nginx.yaml
pods/nginx

查看pod:

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# kubectl get pod nginx
NAME      READY     STATUS                                            RESTARTS   AGE
nginx     0/1       Image: nginx is not ready on the node   0          34s

这里STATUS一直是这个，创建不成功，下面排错。通过查看pod的描述发现如下错误：

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# kubectl describe pod nginx 
Wed, 28 Oct 2015 10:25:30 +0800       Wed, 28 Oct 2015 10:25:30 +0800 1       {kubelet 192.168.0.81}  implicitly required container POD       pulled          Successfully pulled Pod container image "gcr.io/google_containers/pause:0.8.0"
  Wed, 28 Oct 2015 10:25:30 +0800       Wed, 28 Oct 2015 10:25:30 +0800 1       {kubelet 192.168.0.81}  implicitly required container POD       failed          Failed to create docker container with error: no such image
  Wed, 28 Oct 2015 10:25:30 +0800       Wed, 28 Oct 2015 10:25:30 +0800 1       {kubelet 192.168.0.81}                                          failedSync      Error syncing pod, skipping: no such image
  Wed, 28 Oct 2015 10:27:30 +0800       Wed, 28 Oct 2015 10:29:30 +0800 2       {kubelet 192.168.0.81}  implicitly required container POD       failed          Failed to pull image "gcr.io/google_containers/pause:0.8.0": image pull failed for gcr.io/google_containers/pause:0.8.0, this may be because there are no credentials on this request.  details: (API error (500): invalid registry endpoint "http://gcr.io/v0/". HTTPS attempt: unable to ping registry endpoint https://gcr.io/v0/
v2 ping attempt failed with error: Get https://gcr.io/v2/: dial tcp 173.194.72.82:443: i/o timeout

手动ping了一下gcr.io发现无法ping通（可能是被墙了）,从网上找到 pause:0.8.0 的镜像，然后再每个minion上导入镜像:

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# docker load --input pause-0.8.0.tar

附下载：pause-0.8.0.tar 在执行以下命令即可成功创建pod

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# kubectl create -f nginx.yaml
pods/nginx

查看pod

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# kubectl get pod nginx
NAME      READY     STATUS                                            RESTARTS   AGE
nginx      1/1             Running                                            0               2min
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