Kubernetes 1.6 高可用集群部署

我们已经可以很方便的使用kubeadm快速初始化Kubernetes集群，但kubeadm当前还不能用于生产环境，同时kubeadm初始化的集群的Master节点不是高可用的，后端存储etcd也是单点。因此，本文将基于Kubernetes二进制包手动部署一个高可用的Kubernetes 1.6集群，将启用ApiServer的TLS双向认证和RBAC授权等安全机制。通过这个手动部署的过程，我们还可以更加深入理解Kubernetes各组件的交互和运行原理。

kubernetes-ha

1. 环境准备

1.1 系统环境

操作系统CentOS 7.3

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192.168.61.11 node1
192.168.61.12 node2
192.168.61.13 node3

1.2 安装包下载

从这里下载kubernetes二进制安装包：

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wget https://dl.k8s.io/v1.6.2/kubernetes-server-linux-amd64.tar.gz

tar -zxvf kubernetes-server-linux-amd64.tar.g

1.3 系统配置

在各节点创建/etc/sysctl.d/k8s.conf文件，添加如下内容：

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net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1

执行sysctl -p /etc/sysctl.d/k8s.conf使修改生效。

禁用selinux：

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setenforce 0
vi /etc/selinux/config
SELINUX=disabled

1.3 etcd高可用集群部署

Kubernetes使用etcd作为ApiServer的持久化存储，因此需要部署高可用的etcd集群,安全要求我们为etcd集群开启TLS通信和认证。在node1~node3三个节点上部署etcd集群，这里不再展开，可参考前面写的一篇《etcd 3.1 高可用集群搭建》。

最终部署的etcd集群如下：

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node1 https://192.168.61.11:2379
node2 https://192.168.61.12:2379
node3 https://192.168.61.13:2379

1.4 在各节点安装Docker

在集群各个服务器节点上安装Docker。根据最近的文档Kubernetes 1.6还没有针对docker 1.13和最新的docker 17.03上做测试和验证，所以这里安装Kubernetes官方推荐的Docker 1.12版本。Docker的安装比较简单，这里也不展开，可参考《使用kubeadm安装Kubernetes 1.6》中的“安装Docker 1.12”章节。

2. Kubernetes各组件TLS证书和密钥

我们将禁用kube-apiserver的HTTP端口，启用Kubernetes集群相关组件的TLS通信和双向认证，下面将使用工具生成各组件TLS的证书和私钥。

我们将使用cfssl生成所需要的私钥和证书。 cfssl在《etcd 3.1 高可用集群搭建》中已经用过，这里直接使用。

2.1 CA证书和私钥

复用《etcd 3.1 高可用集群搭建》中使用的ca-config.json：

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{
  "signing": {
    "default": {
      "expiry": "87600h"
    },
    "profiles": {
      "frognew": {
        "usages": [
            "signing",
            "key encipherment",
            "server auth",
            "client auth"
        ],
        "expiry": "87600h"
      }
    }
  }
}

创建CA证书签名请求配置ca-csr.json：

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{
  "CN": "kubernetes",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "k8s",
      "OU": "cloudnative"
    }
  ]
}

CN即Common Name，kube-apiserver从证书中提取该字段作为请求的用户名
O即Organization，kube-apiserver 从证书中提取该字段作为请求用户所属的组

下面使用cfss生成CA证书和私钥：

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cfssl gencert -initca ca-csr.json | cfssljson -bare ca

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ls
ca-config.json  ca.csr  ca-csr.json  ca-key.pem  ca.pem

ca-key.pem和ca.pem需要保存在一个安全的地方，后边会用到。

2.2 创建kube-apiserver证书和私钥

创建kube-apiserver证书签名请求配置apiserver-csr.json：

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{
    "CN": "kubernetes",
    "hosts": [
      "127.0.0.1",
      "192.168.61.10",
      "192.168.61.11",
      "192.168.61.12",
      "192.168.61.13",
      "10.96.0.1",
      "kubernetes",
      "kubernetes.default",
      "kubernetes.default.svc",
      "kubernetes.default.svc.cluster",
      "kubernetes.default.svc.cluster.local"
    ],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "ST": "BeiJing",
            "L": "BeiJing",
            "O": "k8s",
            "OU": "cloudnative"
        }
    ]
}

注意上面配置hosts字段中指定授权使用该证书的IP和域名列表，因为现在要生成的证书需要被Kubernetes Master集群各个节点使用，所以这里指定了各个节点的IP和hostname。另外，我们为了实现kube-apiserver的高可用，我们将在其前面部署一个高可用的负载均衡器，Kubernetes的一些核心组件，通过这个负载均衡器和apiserver进行通信，因此这里在证书请求配置的hosts字段中还要加上这个负载均衡器的IP地址，这里是192.168.61.10。同时还要指定集群内部kube-apiserver的多个域名和IP地址10.96.0.1(后边kube-apiserver-service-cluster-ip-range=10.96.0.0/12参数的指定网段的第一个IP)。

下面生成kube-apiserver的证书和私钥：

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cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=frognew apiserver-csr.json | cfssljson -bare apiserver
ls apiserver*
apiserver.csr  apiserver-csr.json  apiserver-key.pem  apiserver.pem

2.3 创建kubernetes-admin客户端证书和私钥

创建admin证书的签名请求配置admin-csr.json：

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{
  "CN": "kubernetes-admin",
  "hosts": [
  	  "192.168.61.11",
      "192.168.61.12",
      "192.168.61.13"
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "system:masters",
      "OU": "cloudnative"
    }
  ]
}

kube-apiserver将提取CN作为客户端的用户名，这里是kubernetes-admin，将提取O作为用户所属的组，这里是system:master。 kube-apiserver预定义了一些 RBAC使用的ClusterRoleBindings，例如 cluster-admin将组system:masters与 ClusterRole cluster-admin绑定，而cluster-admin拥有访问kube-apiserver的所有权限，因此kubernetes-admin这个用户将作为集群的超级管理员。

了解Kubernetes的RBAC和ApiServer的认证的内容可参考之前写过的两篇《Kubernetes 1.6新特性学习：RBAC授权》和《Kubernetes集群安全：Api Server认证》。

下面生成kubernetes-admin的证书和私钥：

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cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=frognew admin-csr.json | cfssljson -bare admin

ls admin*
admin.csr  admin-csr.json  admin-key.pem  admin.pem

2.4 创建kube-controller-manager客户端证书和私钥

下面创建kube-controller-manager客户端访问ApiServer所需的证书和私钥。 controller-manager证书的签名请求配置controller-manager-csr.json：

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{
  "CN": "system:kube-controller-manager",
  "hosts": [
  	  "192.168.61.11",
      "192.168.61.12",
      "192.168.61.13"
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "system:kube-controller-manager",
      "OU": "cloudnative"
    }
  ]
}

kube-apiserver将提取CN作为客户端的用户名，这里是system:kube-controller-manager。 kube-apiserver预定义的 RBAC使用的ClusterRoleBindings system:kube-controller-manager将用户system:kube-controller-manager与ClusterRole system:kube-controller-manager绑定。

下面生成证书和私钥：

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cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=frognew controller-manager-csr.json | cfssljson -bare controller-manager

ls controller-manager*
controller-manager.csr  controller-manager-csr.json  controller-manager-key.pem  controller-manager.pem

2.5 创建kube-scheduler客户端证书和私钥

下面创建kube-scheduler客户端访问ApiServer所需的证书和私钥。 scheduler证书的签名请求配置scheduler-csr.json：

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{
  "CN": "system:kube-scheduler",
  "hosts": [
  	  "192.168.61.11",
      "192.168.61.12",
      "192.168.61.13"
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "system:kube-scheduler",
      "OU": "cloudnative"
    }
  ]
}

kube-scheduler将提取CN作为客户端的用户名，这里是system:kube-scheduler。 kube-apiserver预定义的RBAC使用的ClusterRoleBindings system:kube-scheduler将用户system:kube-scheduler与ClusterRole system:kube-scheduler绑定。

下面生成证书和私钥：

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cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=frognew scheduler-csr.json | cfssljson -bare scheduler

ls scheduler*
scheduler.csr  scheduler-csr.json  scheduler-key.pem  scheduler.pem

3. Kubernetes Master集群部署

部署的Master节点集群由Node1, Node2, Node3三个节点组成，每个节点上部署kube-apiserver,kube-controller-manager,kube-scheduler三个核心组件。 kube-apiserver的3个实例同时提供服务，在其前端部署一个高可用的负载均衡器作为kube-apiserver的地址。 kube-controller-manager和kube-scheduler也是各自3个实例，在同一时刻只能有1个实例工作，这个实例通过选举产生。

将前面生成的 ca.pem, apiserver-key.pem, apiserver.pem, admin.pem, admin-key.pem, controller-manager.pem, controller-manager-key.pem, scheduler-key.pem, scheduler.pem拷贝到各个节点的/etc/kubernetes/pki目录下：

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mkdir -p /etc/kubernetes/pki
cp {ca.pem,apiserver-key.pem,apiserver.pem,admin.pem, admin-key.pem, controller-manager.pem, controller-manager-key.pem,scheduler-key.pem, scheduler.pem} /etc/kubernetes/pki

将Kubernetes二进制包解压后kubernetes/server/bin中的kube-apiserver,kube-controller-manager,kube-scheduler,kubectl,kube-proxy,kubelet拷贝到各节点的/usr/local/bin目录中：

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cp {kube-apiserver,kube-controller-manager,kube-scheduler,kubectl,kube-proxy,kubelet} /usr/local/bin/

3.1 kube-apiserver部署

创建kube-apiserver的systemd unit文件/usr/lib/systemd/system/kube-apiserver.service，注意替换INTERNAL_IP变量的值：

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mkdir -p /var/log/kubernetes
export INTERNAL_IP=192.168.61.11
cat > /usr/lib/systemd/system/kube-apiserver.service <<EOF
[Unit]
Description=kube-apiserver
After=network.target
After=etcd.service

[Service]
EnvironmentFile=-/etc/kubernetes/apiserver
ExecStart=/usr/local/bin/kube-apiserver \
	    --logtostderr=true \
	    --v=0 \
	    --advertise-address=${INTERNAL_IP} \
	    --bind-address=${INTERNAL_IP} \
	    --secure-port=6443 \
	    --insecure-port=0 \
	    --allow-privileged=true \
	    --etcd-servers=https://192.168.61.11:2379,https://192.168.61.12:2379,https://192.168.61.13:2379 \
	    --etcd-cafile=/etc/etcd/ssl/ca.pem \
	    --etcd-certfile=/etc/etcd/ssl/etcd.pem \
	    --etcd-keyfile=/etc/etcd/ssl/etcd-key.pem \
	    --storage-backend=etcd3 \
	    --service-cluster-ip-range=10.96.0.0/12 \
	    --tls-cert-file=/etc/kubernetes/pki/apiserver.pem \
	    --tls-private-key-file=/etc/kubernetes/pki/apiserver-key.pem \
	    --client-ca-file=/etc/kubernetes/pki/ca.pem \
	    --service-account-key-file=/etc/kubernetes/pki/ca-key.pem \
	    --experimental-bootstrap-token-auth=true \
	    --apiserver-count=3 \
	    --enable-swagger-ui=true \
	    --admission-control=NamespaceLifecycle,LimitRanger,ServiceAccount,PersistentVolumeLabel,DefaultStorageClass,ResourceQuota,DefaultTolerationSeconds \
	    --authorization-mode=RBAC \
	    --audit-log-maxage=30 \
	    --audit-log-maxbackup=3 \
	    --audit-log-maxsize=100 \
	    --audit-log-path=/var/log/kubernetes/audit.log
Restart=on-failure
Type=notify
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF

--insecure-port禁用了不安全的http端口
--secure-port指定https安全端口，kube-scheduler、kube-controller-manager、kubelet、kube-proxy、kubectl等组件都将使用安全端口与ApiServer通信(实际上会由我们在前端部署的负载均衡器代理)。
--authorization-mode=RBAC表示在安全端口启用RBAC授权模式，在授权过程会拒绝会授权的请求。kube-scheduler、kube-controller-manager、kubelet、kube-proxy、kubectl等组件都使用各自证书或kubeconfig指定相关的User、Group来通过RBAC授权。
--admission-control为准入机制，这里配置了NamespaceLifecycle,LimitRanger,ServiceAccount,PersistentVolumeLabel,DefaultStorageClass,ResourceQuota,DefaultTolerationSeconds
--service-cluster-ip-range指定Service Cluster IP的地址段，注意该地址段是Kubernetes Service使用的，是虚拟IP，从外部不能路由可达。

启动kube-apiserver:

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systemctl daemon-reload
systemctl enable kube-apiserver
systemctl start kube-apiserver
systemctl status kube-apiserver

3.2 配置kubectl访问apiserver

我们已经部署了kube-apiserver，并且前面已经kubernetes-admin的证书和私钥，我们将使用这个用户访问ApiServer。

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kubectl --server=https://192.168.61.11:6443 \
--certificate-authority=/etc/kubernetes/pki/ca.pem  \
--client-certificate=/etc/kubernetes/pki/admin.pem \
--client-key=/etc/kubernetes/pki/admin-key.pem \
get componentstatuses
NAME                 STATUS      MESSAGE                                                                                        ERROR
scheduler            Unhealthy   Get http://127.0.0.1:10251/healthz: dial tcp 127.0.0.1:10251: getsockopt: connection refused
controller-manager   Unhealthy   Get http://127.0.0.1:10252/healthz: dial tcp 127.0.0.1:10252: getsockopt: connection refused
etcd-0               Healthy     {"health": "true"}
etcd-2               Healthy     {"health": "true"}
etcd-1               Healthy     {"health": "true"}

上面我们使用kubectl命令打印出了Kubernetes核心组件的状态，因为我们还没有部署kube-scheduler和controller-manager，所以这两个组件当前是不健康的。

前面面使用kubectl时需要指定ApiServer的地址以及客户端的证书，用起来比较繁琐。接下来我们创建kubernetes-admin的kubeconfig文件 admin.conf。

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cd /etc/kubernetes
export KUBE_APISERVER="https://192.168.61.11:6443"

# set-cluster
kubectl config set-cluster kubernetes \
  --certificate-authority=/etc/kubernetes/pki/ca.pem \
  --embed-certs=true \
  --server=${KUBE_APISERVER} \
  --kubeconfig=admin.conf

# set-credentials
kubectl config set-credentials kubernetes-admin \
  --client-certificate=/etc/kubernetes/pki/admin.pem \
  --embed-certs=true \
  --client-key=/etc/kubernetes/pki/admin-key.pem \
  --kubeconfig=admin.conf

# set-context
kubectl config set-context kubernetes-admin@kubernetes \
  --cluster=kubernetes \
  --user=kubernetes-admin \
  --kubeconfig=admin.conf
  
# set default context
kubectl config use-context kubernetes-admin@kubernetes --kubeconfig=admin.conf

为了使用kubectl访问apiserver使用admin.conf，将其拷贝到$HOME/.kube中并重命名成config：

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cp /etc/kubernetes/admin.conf ~/.kube/config

尝试直接使用kubectl命令访问apiserver：

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kubectl get cs
NAME                 STATUS      MESSAGE                                                                                        ERROR
scheduler            Unhealthy   Get http://127.0.0.1:10251/healthz: dial tcp 127.0.0.1:10251: getsockopt: connection refused
controller-manager   Unhealthy   Get http://127.0.0.1:10252/healthz: dial tcp 127.0.0.1:10252: getsockopt: connection refused
etcd-0               Healthy     {"health": "true"}
etcd-1               Healthy     {"health": "true"}
etcd-2               Healthy     {"health": "true"}

因为我们已经把kubernetes-admin用户的相关信息和证书保存到了admin.conf中，所以可以删除/etc/kubernetes/pki中的admin.pem和admin-key.pem:

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cd /etc/kubernetes/pki
rm -f admin.pem admin-key.pem

3.3 kube-apiserver高可用

经过前面的步骤，我们已经在node1,node2,node3上部署了Kubernetes Master节点的kube-apiserver，地址如下：

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https://192.168.61.11:6443
https://192.168.61.12:6443
https://192.168.61.13:6443

为了实现高可用，可以在前面放一个负载均衡器来代理访问kube-apiserver的请求，再对负载均衡器实现高可用。例如，HAProxy+Keepavlided，我们在node1~node3这3个Master节点上运行keepalived和HAProxy，3个keepalived争抢同一个VIP地址，3个HAProxy也都尝试去绑定到这个VIP的同一个端口。例如：192.168.61.10:5000，当某个Haproxy出现异常后，其他节点上的Keepalived会争抢到VIP，同时这个节点上HAProxy会接管流量。

HAProxy+Keepavlided的部署这里不再展开。最终kube-apiserver高可用的地址为https://192.168.61.10:5000，修改前面$HOME/.kube/config中的clusters:cluster:server的值为这个地址。

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kubectl get cs
NAME                 STATUS      MESSAGE                                                                                        ERROR
scheduler            Unhealthy   Get http://127.0.0.1:10251/healthz: dial tcp 127.0.0.1:10251: getsockopt: connection refused
controller-manager   Unhealthy   Get http://127.0.0.1:10252/healthz: dial tcp 127.0.0.1:10252: getsockopt: connection refused
etcd-0               Healthy     {"health": "true"}
etcd-1               Healthy     {"health": "true"}
etcd-2               Healthy     {"health": "true"}

3.4 kube-controller-manager部署

前面已经创建了controller-manager.pem和controller-manage-key.pem，下面生成controller-manager的kubeconfig文件controller-manager.conf：

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cd /etc/kubernetes
export KUBE_APISERVER="https://192.168.61.10:5000"

# set-cluster
kubectl config set-cluster kubernetes \
  --certificate-authority=/etc/kubernetes/pki/ca.pem \
  --embed-certs=true \
  --server=${KUBE_APISERVER} \
  --kubeconfig=controller-manager.conf

# set-credentials
kubectl config set-credentials system:kube-controller-manager \
  --client-certificate=/etc/kubernetes/pki/controller-manager.pem \
  --embed-certs=true \
  --client-key=/etc/kubernetes/pki/controller-manager-key.pem \
  --kubeconfig=controller-manager.conf

# set-context
kubectl config set-context system:kube-controller-manager@kubernetes \
  --cluster=kubernetes \
  --user=system:kube-controller-manager \
  --kubeconfig=controller-manager.conf
  
# set default context
kubectl config use-context system:kube-controller-manager@kubernetes --kubeconfig=controller-manager.conf

controller-manager.conf文件生成后将这个文件分发到各个Master节点的/etc/kubernetes目录下。

创建kube-controller-manager的systemd unit文件/usr/lib/systemd/system/kube-controller-manager.service：

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export KUBE_APISERVER="https://192.168.61.10:5000"
cat > /usr/lib/systemd/system/kube-controller-manager.service <<EOF
[Unit]
Description=kube-controller-manager
After=network.target
After=kube-apiserver.service

[Service]
EnvironmentFile=-/etc/kubernetes/controller-manager
ExecStart=/usr/local/bin/kube-controller-manager \
	    --logtostderr=true \
	    --v=0 \
	    --master=${KUBE_APISERVER} \
	    --kubeconfig=/etc/kubernetes/controller-manager.conf \
	    --cluster-name=kubernetes \
	    --cluster-signing-cert-file=/etc/kubernetes/pki/ca.pem \
	    --cluster-signing-key-file=/etc/kubernetes/pki/ca-key.pem \
	    --service-account-private-key-file=/etc/kubernetes/pki/ca-key.pem \
	    --root-ca-file=/etc/kubernetes/pki/ca.pem \
	    --insecure-experimental-approve-all-kubelet-csrs-for-group=system:bootstrappers \
	    --use-service-account-credentials=true \
	    --service-cluster-ip-range=10.96.0.0/12 \
	    --cluster-cidr=10.244.0.0/16 \
	    --allocate-node-cidrs=true \
	    --leader-elect=true \
	    --controllers=*,bootstrapsigner,tokencleaner
Restart=on-failure
Type=simple
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF

--service-cluster-ip-range和kube-api-server中指定的参数值一致

在各节点上启动:

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systemctl daemon-reload
systemctl enable kube-controller-manager
systemctl start kube-controller-manager
systemctl status kube-controller-manager

在node1,node2,node3上完成部署和启动后，查看一下状态：

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kubectl get cs
NAME                 STATUS      MESSAGE                                                                                        ERROR
scheduler            Unhealthy   Get http://127.0.0.1:10251/healthz: dial tcp 127.0.0.1:10251: getsockopt: connection refused
controller-manager   Healthy     ok
etcd-1               Healthy     {"health": "true"}
etcd-2               Healthy     {"health": "true"}
etcd-0               Healthy     {"health": "true"}

到这一步三个Master节点上的kube-controller-manager部署完成，通过选举出一个leader工作。分别在三个节点查看状态：

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#node1
systemctl status -l kube-controller-manager
......
...... attempting to acquire leader lease...

#node2
systemctl status -l kube-controller-manager
......
...... controllermanager.go:437] Started "endpoint"
...... controllermanager.go:437] Started "replicationcontroller"
...... replication_controller.go:150] Starting RC Manager
...... controllermanager.go:437] Started "replicaset"
...... replica_set.go:155] Starting ReplicaSet controller
...... controllermanager.go:437] Started "disruption"
...... disruption.go:269] Starting disruption controller
...... controllermanager.go:437] Started "statefuleset"
...... stateful_set.go:144] Starting statefulset controller
...... controllermanager.go:437] Started "bootstrapsigner"

#node3
systemctl status -l kube-controller-manager
......
...... attempting to acquire leader lease...

从输出的日志可以看出现在第二个节点上的kube-controller-manager。

3.5 kube-scheduler部署

前面已经创建了scheduler.pem和scheduler-key.pem，下面生成kube-scheduler的kubeconfig文件scheduler.conf：

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cd /etc/kubernetes
export KUBE_APISERVER="https://192.168.61.10:5000"

# set-cluster
kubectl config set-cluster kubernetes \
  --certificate-authority=/etc/kubernetes/pki/ca.pem \
  --embed-certs=true \
  --server=${KUBE_APISERVER} \
  --kubeconfig=scheduler.conf

# set-credentials
kubectl config set-credentials system:kube-scheduler \
  --client-certificate=/etc/kubernetes/pki/scheduler.pem \
  --embed-certs=true \
  --client-key=/etc/kubernetes/pki/scheduler-key.pem \
  --kubeconfig=scheduler.conf

# set-context
kubectl config set-context system:kube-scheduler@kubernetes \
  --cluster=kubernetes \
  --user=system:kube-scheduler \
  --kubeconfig=scheduler.conf
  
# set default context
kubectl config use-context system:kube-scheduler@kubernetes --kubeconfig=scheduler.conf

scheduler.conf文件生成后将这个文件分发到各个Master节点的/etc/kubernetes目录下。

创建kube-scheduler的systemd unit文件/usr/lib/systemd/system/kube-scheduler.service：

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export KUBE_APISERVER="https://192.168.61.10:5000"
cat > /usr/lib/systemd/system/kube-scheduler.service <<EOF
[Unit]
Description=kube-scheduler
After=network.target
After=kube-apiserver.service

[Service]
EnvironmentFile=-/etc/kubernetes/scheduler
ExecStart=/usr/local/bin/kube-scheduler \
	    --logtostderr=true \
	    --v=0 \
	    --master=${KUBE_APISERVER} \
	    --kubeconfig=/etc/kubernetes/scheduler.conf \
	    --leader-elect=true
Restart=on-failure
Type=simple
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF

在各节点上启动：

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systemctl daemon-reload
systemctl enable kube-scheduler
systemctl start kube-scheduler
systemctl status kube-scheduler

到这一步三个Master节点上的kube-scheduler部署完成，通过选举出一个leader工作。

查看Kubernetes Master集群各个核心组件的状态全部正常。

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kubectl get cs
NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok
scheduler            Healthy   ok
etcd-2               Healthy   {"health": "true"}
etcd-0               Healthy   {"health": "true"}
etcd-1               Healthy   {"health": "true"}

4. Kubernetes Node节点部署

Kubernetes的一个Node节点上需要运行如下组件：

Docker，这个我们前面在做环境准备的时候已经在各节点部署和运行了
kubelet
kube-proxy

下面我们以在node1上为例部署这些组件：

4.1 CNI安装

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wget https://github.com/containernetworking/cni/releases/download/v0.5.2/cni-amd64-v0.5.2.tgz
mkdir -p /opt/cni/bin
tar -zxvf cni-amd64-v0.5.2.tgz -C /opt/cni/bin
ls /opt/cni/bin/
bridge  cnitool  dhcp  flannel  host-local  ipvlan  loopback  macvlan  noop  ptp  tuning

4.2 kubelet部署

首先确认将kubelet的二进制文件拷贝到/usr/local/bin下。创建kubelet的工作目录：

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mkdir -p /var/lib/kubelet

安装依赖包：

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yum install ebtables socat util-linux conntrack-tools

接下来创建访问ApiServer的证书和私钥，kubelet-csr.json：

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{
  "CN": "system:node:node1",
  "hosts": [
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "system:nodes",
      "OU": "cloudnative"
    }
  ]
}

注意CN为用户名，使用system:node:<node-name>
O为用户组，Kubernetes RBAC定义了ClusterRoleBinding将Group system:nodes和ClusterRole system:node关联。

生成证书和私钥：

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cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=frognew kubelet-csr.json | cfssljson -bare kubelet
ls kubelet*
kubelet.csr  kubelet-csr.json  kubelet-key.pem  kubelet.pem

生成kubeconfig文件kubelet.conf：

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cd /etc/kubernetes
export KUBE_APISERVER="https://192.168.61.10:5000"
# set-cluster
kubectl config set-cluster kubernetes \
  --certificate-authority=/etc/kubernetes/pki/ca.pem \
  --embed-certs=true \
  --server=${KUBE_APISERVER} \
  --kubeconfig=kubelet.conf
# set-credentials
kubectl config set-credentials system:node:node1 \
  --client-certificate=/etc/kubernetes/pki/kubelet.pem \
  --embed-certs=true \
  --client-key=/etc/kubernetes/pki/kubelet-key.pem \
  --kubeconfig=kubelet.conf
# set-context
kubectl config set-context system:node:node1@kubernetes \
  --cluster=kubernetes \
  --user=system:node:node1 \
  --kubeconfig=kubelet.conf
# set default context
kubectl config use-context system:node:node1@kubernetes --kubeconfig=kubelet.conf

创建kubelet的systemd unit service文件，注意替换NodeIP变量：

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export KUBE_APISERVER="https://192.168.61.10:5000"
export NodeIP="192.168.61.11"
cat > /usr/lib/systemd/system/kubelet.service <<EOF
[Unit]
Description=kubelet
After=docker.service
Requires=docker.service

[Service]
WorkingDirectory=/var/lib/kubelet
EnvironmentFile=-/etc/kubernetes/kubelet
ExecStart=/usr/local/bin/kubelet \
        --logtostderr=true \
        --v=0 \
        --address=${NodeIP} \
        --api-servers==${KUBE_APISERVER} \
        --cluster-dns=10.96.0.10 \
        --cluster-domain=cluster.local \
        --kubeconfig=/etc/kubernetes/kubelet.conf \
        --require-kubeconfig=true \
        --pod-manifest-path=/etc/kubernetes/manifests \
        --allow-privileged=true \
        --authorization-mode=AlwaysAllow \
#        --authorization-mode=Webhook \
#        --client-ca-file=/etc/kubernetes/pki/ca.pem \
        --network-plugin=cni \
        --cni-conf-dir=/etc/cni/net.d \
        --cni-bin-dir=/opt/cni/bin
Restart=on-failure

[Install]
WantedBy=multi-user.target
EOF

--pod-manifest-path=/etc/kubernetes/manifests指定了静态Pod定义的目录。可以提前创建好这个目录mkdir -p /etc/kubernetes/manifests。关于静态Pod的内容可参考之前写的一篇《Kubernetes资源对象之Pod》中的静态Pod的内容。
--authorization-mode=AlwaysAllow 这里并没有启用Kubernetes 1.5的新特性即kubelet API的认证授权功能，先设置AlwaysAllow和我们的线上环境保持一致

启动kubelet:

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systemctl daemon-reload
systemctl enable kubelet
systemctl start kubelet
systemctl status kubelet

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kubectl get nodes
NAME      STATUS    AGE       VERSION
node1     NotReady     35s       v1.6.2

4.3 kube-proxy部署

首先确认已经将kuber-proxy的二进制文件拷贝到/usr/local/bin下。创建kubelet的工作目录：

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mkdir -p /var/lib/kube-proxy

接下来创建访问ApiServer的证书和私钥，kube-proxy-csr.json：

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{
  "CN": "system:kube-proxy",
  "hosts": [
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "BeiJing",
      "L": "BeiJing",
      "O": "system:kube-proxy",
      "OU": "cloudnative"
    }
  ]
}

CN 指定该证书的 User为 system:kube-proxy。Kubernetes RBAC定义了ClusterRoleBinding将system:kube-proxy用户与system:node-proxier 角色绑定。system:node-proxier具有kube-proxy组件访问ApiServer的相关权限。

生成证书和私钥：

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cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=frognew kube-proxy-csr.json | cfssljson -bare kube-proxy
ls kube-proxy*
kube-proxy.csr  kube-proxy-csr.json  kube-proxy-key.pem  kube-proxy.pem

生成kubeconfig文件kube-proxy.conf：

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cd /etc/kubernetes
export KUBE_APISERVER="https://192.168.61.10:5000"
# set-cluster
kubectl config set-cluster kubernetes \
  --certificate-authority=/etc/kubernetes/pki/ca.pem \
  --embed-certs=true \
  --server=${KUBE_APISERVER} \
  --kubeconfig=kube-proxy.conf
# set-credentials
kubectl config set-credentials system:kube-proxy \
  --client-certificate=/etc/kubernetes/pki/kube-proxy.pem \
  --embed-certs=true \
  --client-key=/etc/kubernetes/pki/kube-proxy-key.pem \
  --kubeconfig=kube-proxy.conf
# set-context
kubectl config set-context system:kube-proxy@kubernetes \
  --cluster=kubernetes \
  --user=system:kube-proxy \
  --kubeconfig=kube-proxy.conf
# set default context
kubectl config use-context system:kube-proxy@kubernetes --kubeconfig=kube-proxy.conf

创建kube-proxy的systemd unit service文件，注意替换NodeIP变量：

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export KUBE_APISERVER="https://192.168.61.10:5000"
export NodeIP="192.168.61.11"
cat > /usr/lib/systemd/system/kube-proxy.service <<EOF
[Unit]
Description=kube-proxy
After=network.target

[Service]
WorkingDirectory=/var/lib/kube-proxy
EnvironmentFile=-/etc/kubernetes/kube-proxy
ExecStart=/usr/local/bin/kube-proxy \
        --logtostderr=true \
        --v=0 \
        --bind-address=${NodeIP} \
        --kubeconfig=/etc/kubernetes/kube-proxy.conf \
        --cluster-cidr=10.244.0.0/16
        
Restart=on-failure

[Install]
WantedBy=multi-user.target
EOF

启动kubelet-proxy:

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systemctl daemon-reload
systemctl enable kube-proxy
systemctl start kube-proxy
systemctl status -l kube-proxy

4.4 部署Pod Network插件flannel

flannel以DaemonSet的形式运行在Kubernetes集群中。由于我们的etcd集群启用了TLS认证，为了从flannel容器中能访问etcd，我们先把etcd的TLS证书信息保存到Kubernetes的Secret中。

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kubectl create secret generic etcd-tls-secret  --from-file=/etc/etcd/ssl/etcd.pem --from-file=/etc/etcd/ssl/etcd-key.pem  --from-file=/etc/etcd/ssl/ca.pem -n kube-system


kubectl describe secret etcd-tls-secret -n kube-system
Name:           etcd-tls-secret
Namespace:      kube-system
Labels:         <none>
Annotations:    <none>

Type:   Opaque

Data
====
etcd-key.pem:   1675 bytes
etcd.pem:       1489 bytes
ca.pem:         1330 bytes

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mkdir -p ~/k8s/flannel
cd ~/k8s/flannel
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel-rbac.yml
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

对kube-flannel.yml做以下修改：

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apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  ......
spec:
  template:
    metadata:
      ......
    spec:
      ......
      containers:
      - name: kube-flannel
        image: quay.io/coreos/flannel:v0.7.1-amd64
        command: [
             "/opt/bin/flanneld",
             "--ip-masq",
             "--kube-subnet-mgr",
             "-etcd-endpoints=https://192.168.61.11:2379,https://192.168.61.12:2379,https://192.168.61.13:2379",
             "-etcd-cafile=/etc/etcd/ssl/ca.pem",
             "--etcd-certfile=/etc/etcd/ssl/etcd.pem",
             "-etcd-keyfile=/etcd/etcd/ssl/etcd-key.pem",
             "--iface=etn0" ]
        securityContext:
          privileged: true
        ......
        volumeMounts:
        ......
        - name: etcd-tls-secret
          readOnly: true
          mountPath: /etc/etcd/ssl/
      ......
      volumes:
        ......
        - name: etcd-tls-secret
          secret:
            secretName: etcd-tls-secret

flanneld的启动参数中加入以下参数
-etcd-endpoints配置etcd集群的访问地址
-etcd-cafile配置etcd的CA证书,/etc/etcd/ssl/ca.pem从etcd-tls-secret这个Secret挂载
--etcd-certfile配置etcd的公钥证书,/etc/etcd/ssl/etcd.pem从etcd-tls-secret这个Secret挂载
--etcd-keyfile配置etcd的私钥,/etc/etcd/ssl/etcd-key.pem从etcd-tls-secret这个Secret挂载
--iface当Node节点有多个网卡时用于指明具体的网卡名称

下面部署flannel：

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kubectl create -f kube-flannel-rbac.yml
kubectl create -f kube-flannel.yml

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kubectl get pods --all-namespaces
NAMESPACE     NAME                    READY     STATUS    RESTARTS   AGE
kube-system   kube-flannel-ds-dhz6m   2/2       Running   0          10s

ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1450
        inet 10.244.0.0  netmask 255.255.255.255  broadcast 0.0.0.0
        ether c2:e6:ad:26:f5:f6  txqueuelen 0  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 1 overruns 0  carrier 0  collisions 0

4.5 部署kube-dns插件

Kubernetes支持kube-dns以Cluster Add-On的形式运行。Kubernetes会在集群中调度一个DNS的Pod和Service。

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mkdir -p ~/k8s/kube-dns
wget https://raw.githubusercontent.com/kubernetes/kubernetes/master/cluster/addons/dns/kubedns-cm.yaml
wget https://raw.githubusercontent.com/kubernetes/kubernetes/master/cluster/addons/dns/kubedns-sa.yaml
wget https://raw.githubusercontent.com/kubernetes/kubernetes/master/cluster/addons/dns/kubedns-svc.yaml.base
wget https://raw.githubusercontent.com/kubernetes/kubernetes/master/cluster/addons/dns/kubedns-controller.yaml.base
wget https://raw.githubusercontent.com/kubernetes/kubernetes/master/cluster/addons/dns/transforms2sed.sed

查看transforms2sed.sed：

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s/__PILLAR__DNS__SERVER__/$DNS_SERVER_IP/g
s/__PILLAR__DNS__DOMAIN__/$DNS_DOMAIN/g
s/__MACHINE_GENERATED_WARNING__/Warning: This is a file generated from the base underscore template file: __SOURCE_FILENAME__/g

将$DNS_SERVER_IP替换成10.96.0.10，将DNS_DOMAIN替换成cluster.local.。注意$DNS_SERVER_IP要和kubelet设置的--cluster-dns参数一致

执行：

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cd ~/k8s/kube-dns
sed -f transforms2sed.sed kubedns-svc.yaml.base > kubedns-svc.yaml
sed -f transforms2sed.sed kubedns-controller.yaml.base > kubedns-controller.yaml

上面的变量DNS_SERVER要和kubelet设置的--cluster-dns参数一致。

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kubectl create -f kubedns-cm.yaml
kubectl create -f kubedns-sa.yaml
kubectl create -f kubedns-svc.yaml
kubectl create -f kubedns-controller.yaml 

查看kube-dns的Pod，确认所有Pod都处于Running状态：

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 kubectl get pods --all-namespaces
NAMESPACE     NAME                       READY     STATUS    RESTARTS   AGE
kube-system   kube-dns-806549836-rv4mm   3/3       Running   0          12s
kube-system   kube-flannel-ds-jnpg9      2/2       Running   0          5m

测试一下DNS功能是否好用：

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kubectl run curl --image=radial/busyboxplus:curl -i --tty

nslookup kubernetes.default
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes
Address 1: 10.96.0.1 kubernetes.default.svc.cluster.local

kube-dns是Kubernetes实现服务发现的重要组件之一，默认情况下只会创建一个DNS Pod，在生产环境中我们可能需要对kube-dns进行扩容。有两种方式：

手动扩容 kubectl --namespace=kube-system scale deployment kube-dns --replicas=<NUM_YOU_WANT>
使用DNS Horizontal Autoscaler

4.6 添加新的Node节点

重复4.1~4.3的步骤，添加新的Node节点。在添加新节点时注意以下事项：

4.2中生成kubelet访问ApiServer的证书和私钥，以及基于证书生成kubeconfig文件时，CN用户名使用system:node:<node-name>。每个Node节点是不同的。
4.3中不需要再生成kube-proxy访问ApiServer的证书和私钥，只需将已有Node节点上的kubeconfig文件kube-proxy.conf分发到新的节点上即可。

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kubectl get nodes
NAME      STATUS    AGE       VERSION
node1     Ready     2h        v1.6.2
node2     Ready     12m       v1.6.2
node3     Ready     10m       v1.6.2

注意生产环境是需要将Master节点隔离的，不建议在Master节点跑工作负载。因为测试环境机器有限，所以这里的Node节点也是node1~node3。

5. dashboard插件部署

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mkdir -p ~/k8s/dashboard
cd ~/k8s/dashboard
wget https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/kubernetes-dashboard.yaml
kubectl create -f kubernetes-dashboard.yaml

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kubectl get pod,svc -n kube-system -l app=kubernetes-dashboard
NAME                                       READY     STATUS    RESTARTS   AGE
po/kubernetes-dashboard-2457468166-5q9xk   1/1       Running   0          6m

NAME                       CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
svc/kubernetes-dashboard   10.102.242.110   <nodes>       80:31632/TCP   6m

6. heapster插件部署

下面安装Heapster为集群添加使用统计和监控功能，为Dashboard添加仪表盘。使用InfluxDB做为Heapster的后端存储，开始部署：

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mkdir -p ~/k8s/heapster
cd ~/k8s/heapster
wget https://raw.githubusercontent.com/kubernetes/heapster/master/deploy/kube-config/influxdb/grafana.yaml
wget https://raw.githubusercontent.com/kubernetes/heapster/master/deploy/kube-config/rbac/heapster-rbac.yaml
wget https://raw.githubusercontent.com/kubernetes/heapster/master/deploy/kube-config/influxdb/heapster.yaml
wget https://raw.githubusercontent.com/kubernetes/heapster/master/deploy/kube-config/influxdb/influxdb.yaml

kubectl create -f ./

最后确认所有的pod都处于running状态，打开Dashboard,集群的使用统计会以仪表盘的形式显示出来。

7. 部署示例应用

接下来部署一个基于微服务的应用，做一个测试：

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kubectl create namespace sock-shop
kubectl apply -n sock-shop -f "https://github.com/microservices-demo/microservices-demo/blob/master/deploy/kubernetes/complete-demo.yaml?raw=true"

这个应用服务的镜像较多，需要耐心等待：

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kubectl get pod -n sock-shop -o wide
NAME                            READY     STATUS    RESTARTS   AGE       IP            NODE
carts-153328538-8r4pv           1/1       Running   0          12m       10.244.0.10   node1
carts-db-4256839670-cw9pr       1/1       Running   0          12m       10.244.0.9    node1
catalogue-114596073-z2079       1/1       Running   0          12m       10.244.2.5    node3
catalogue-db-1956862931-ld598   1/1       Running   0          12m       10.244.1.6    node2
front-end-3570328172-vfj7r      1/1       Running   0          12m       10.244.0.11   node1
orders-2365168879-h3zwr         1/1       Running   0          12m       10.244.1.7    node2
orders-db-836712666-954nd       1/1       Running   0          12m       10.244.2.6    node3
payment-1968871107-9511t        1/1       Running   0          12m       10.244.0.12   node1
queue-master-2798459664-h99nt   1/1       Running   0          12m       10.244.1.8    node2
rabbitmq-3429198581-2hvzl       1/1       Running   0          12m       10.244.2.7    node3
shipping-2899287913-kxt4k       1/1       Running   0          12m       10.244.0.13   node1
user-468431046-6tf0w            1/1       Running   0          11m       10.244.1.9    node2
user-db-1166754267-qrqnf        1/1       Running   0          11m       10.244.2.8    node3

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kubectl -n sock-shop get svc front-end
NAME        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
front-end   10.103.64.184   <nodes>       80:30001/TCP   13m

大功告成O(∩_∩)O~，在浏览器中打开http://<NodeIP>:30001,浏览一下这个应用吧。