部署 master 节点

kubernetes master 节点包含的组件:

  • kube-apiserver
  • kube-scheduler
  • kube-controller-manager

目前这三个组件需要部署在同一台机器上:

  • kube-schedulerkube-controller-managerkube-apiserver 三者的功能紧密相关;
  • 同时只能有一个 kube-schedulerkube-controller-manager 进程处于工作状态,如果运行多个,则需要通过选举产生一个 leader;

本文档介绍部署单机 kubernetes master 节点的步骤,没有实现高可用 master 集群

计划后续再介绍部署 LB 的步骤,客户端 (kubectl、kubelet、kube-proxy) 使用 LB 的 VIP 来访问 kube-apiserver,从而实现高可用 master 集群。

master 节点与 node 节点上的 Pods 通过 Pod 网络通信,所以需要在 master 节点上部署 Flannel 网络。

使用的变量

本文档用到的变量定义如下:

$ export MASTER_IP=192.168.202.131  # 替换为当前部署的 master 机器 IP
$ # 导入用到的其它全局变量:SERVICE_CIDR、CLUSTER_CIDR、NODE_PORT_RANGE、ETCD_ENDPOINTS、BOOTSTRAP_TOKEN
$ source /root/local/bin/environment.sh
$

下载最新版本的二进制文件

有两种下载方式:

  1. github release 页面 下载发布版 tarball,解压后再执行下载脚本

     $ wget https://github.com/kubernetes/kubernetes/releases/download/v1.6.2/kubernetes.tar.gz
     $ tar -xzvf kubernetes.tar.gz
     ...
     $ cd kubernetes
     $ ./cluster/get-kube-binaries.sh
     ...
    
  2. CHANGELOG页面 下载 clientserver tarball 文件

    server 的 tarball kubernetes-server-linux-amd64.tar.gz 已经包含了 client(kubectl) 二进制文件,所以不用单独下载kubernetes-client-linux-amd64.tar.gz文件;

     $ # wget https://dl.k8s.io/v1.6.2/kubernetes-client-linux-amd64.tar.gz
     $ wget https://dl.k8s.io/v1.6.2/kubernetes-server-linux-amd64.tar.gz
     $ tar -xzvf kubernetes-server-linux-amd64.tar.gz
     ...
     $ cd kubernetes
     $ tar -xzvf  kubernetes-src.tar.gz
    

将二进制文件拷贝到指定路径:

$ sudo cp -r server/bin/{kube-apiserver,kube-controller-manager,kube-scheduler,kubectl,kube-proxy,kubelet} /root/local/bin/
$

安装和配置 flanneld

参考 Flannel安装与配置.md

创建 kubernetes 证书

创建 kubernetes 证书签名请求

$ cat > kubernetes-csr.json <<EOF
{
  "CN": "kubernetes",
  "hosts": [
    "127.0.0.1",
    "${MASTER_IP}",
    "10.254.0.1",
    "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": "System"
    }
  ]
}
EOF
  • 如果 hosts 字段不为空则需要指定授权使用该证书的 IP 或域名列表,所以上面分别指定了当前部署的 master 节点主机 IP;
  • 还需要添加 kube-apiserver 注册的名为 kubernetes 的服务 IP (Service Cluster IP),一般是 kube-apiserver --service-cluster-ip-range 选项值指定的网段的第一个IP,如 "10.254.0.1";

    $ kubectl get svc kubernetes
    NAME         CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
    kubernetes   10.254.0.1   <none>        443/TCP   1d
    

生成 kubernetes 证书和私钥

$ cfssl gencert -ca=/etc/kubernetes/ssl/ca.pem \
  -ca-key=/etc/kubernetes/ssl/ca-key.pem \
  -config=/etc/kubernetes/ssl/ca-config.json \
  -profile=kubernetes kubernetes-csr.json | cfssljson -bare kubernetes
$ ls kubernetes*
kubernetes.csr  kubernetes-csr.json  kubernetes-key.pem  kubernetes.pem
$ sudo mkdir -p /etc/kubernetes/ssl/
$ sudo mv kubernetes*.pem /etc/kubernetes/ssl/
$ rm kubernetes.csr  kubernetes-csr.json

配置和启动 kube-apiserver

创建 kube-apiserver 使用的客户端 token 文件

kubelet 首次启动时向 kube-apiserver 发送 TLS Bootstrapping 请求,kube-apiserver 验证 kubelet 请求中的 token 是否与它配置的 token.csv 一致,如果一致则自动为 kubelet生成证书和秘钥。

$ # 导入的 environment.sh 文件定义了 BOOTSTRAP_TOKEN 变量
$ cat > token.csv <<EOF
${BOOTSTRAP_TOKEN},kubelet-bootstrap,10001,"system:kubelet-bootstrap"
EOF
$ mv token.csv /etc/kubernetes/
$

创建 kube-apiserver 的 systemd unit 文件

$ cat  kube-apiserver.service
[Unit]
Description=Kubernetes API Service
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=network.target
After=etcd.service

[Service]
EnvironmentFile=-/etc/kubernetes/config
EnvironmentFile=-/etc/kubernetes/apiserver
ExecStart=/usr/bin/kube-apiserver \
        $KUBE_LOGTOSTDERR \
        $KUBE_LOG_LEVEL \
        $KUBE_ETCD_SERVERS \
        $KUBE_API_ADDRESS \
        $KUBE_API_PORT \
        $KUBELET_PORT \
        $KUBE_ALLOW_PRIV \
        $KUBE_SERVICE_ADDRESSES \
        $KUBE_ADMISSION_CONTROL \
        $KUBE_API_ARGS
Restart=on-failure
Type=notify
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

/etc/kubernetes/config文件的内容为:

###
# 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=true"

# How the controller-manager, scheduler, and proxy find the apiserver
KUBE_MASTER="--master=http://192.168.202.131:8080"

该配置文件同时被kube-apiserver、kube-controller-manager、kube-scheduler、kubelet、kube-proxy使用。

apiserver配置文件/etc/kubernetes/apiserver内容为:

###
## 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="--insecure-bind-address=sz-pg-oam-docker-test-001.tendcloud.com"
KUBE_API_ADDRESS="--advertise-address=192.168.202.131 --bind-address=192.168.202.131 --insecure-bind-address=192.168.202.131"
#
## 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=https://192.168.202.131:2379,192.168.202.132:2379,192.168.202.133:2379"
#
## 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=ServiceAccount,NamespaceLifecycle,NamespaceExists,LimitRanger,ResourceQuota"
#
## Add your own!
KUBE_API_ARGS="--authorization-mode=RBAC --runtime-config=rbac.authorization.k8s.io/v1beta1 --kubelet-https=true --experimental-bootstrap-token-auth --token-auth-file=/etc/kubernetes/token.csv --service-node-port-range=30000-32767 --tls-cert-file=/etc/kubernetes/ssl/kubernetes.pem --tls-private-key-file=/etc/kubernetes/ssl/kubernetes-key.pem --client-ca-file=/etc/kubernetes/ssl/ca.pem --service-account-key-file=/etc/kubernetes/ssl/ca-key.pem --etcd-cafile=/etc/kubernetes/ssl/ca.pem --etcd-certfile=/etc/kubernetes/ssl/kubernetes.pem --etcd-keyfile=/etc/kubernetes/ssl/kubernetes-key.pem --enable-swagger-ui=true --apiserver-count=3 --audit-log-maxage=30 --audit-log-maxbackup=3 --audit-log-maxsize=100 --audit-log-path=/var/lib/audit.log --event-ttl=1h"
  • kube-apiserver 1.6 版本开始使用 etcd v3 API 和存储格式;
  • --authorization-mode=RBAC 指定在安全端口使用 RBAC 授权模式,拒绝未通过授权的请求;
  • kube-scheduler、kube-controller-manager 一般和 kube-apiserver 部署在同一台机器上,它们使用非安全端口和 kube-apiserver通信;
  • kubelet、kube-proxy、kubectl 部署在其它 Node 节点上,如果通过安全端口访问 kube-apiserver,则必须先通过 TLS 证书认证,再通过 RBAC 授权;
  • kube-proxy、kubectl 通过在使用的证书里指定相关的 User、Group 来达到通过 RBAC 授权的目的;
  • 如果使用了 kubelet TLS Boostrap 机制,则不能再指定 --kubelet-certificate-authority--kubelet-client-certificate--kubelet-client-key 选项,否则后续 kube-apiserver 校验 kubelet 证书时出现 ”x509: certificate signed by unknown authority“ 错误;
  • --admission-control 值必须包含 ServiceAccount,否则部署集群插件时会失败;
  • --bind-address 不能为 127.0.0.1
  • --service-cluster-ip-range 指定 Service Cluster IP 地址段,该地址段不能路由可达;
  • --service-node-port-range 指定 NodePort 的端口范围;
  • 缺省情况下 kubernetes 对象保存在 etcd /registry 路径下,可以通过 --etcd-prefix 参数进行调整;

完整 unit 见 kube-apiserver.service

启动 kube-apiserver

$ sudo cp kube-apiserver.service /etc/systemd/system/
$ sudo systemctl daemon-reload
$ sudo systemctl enable kube-apiserver
$ sudo systemctl start kube-apiserver
$ sudo systemctl status kube-apiserver
$

配置和启动 kube-controller-manager

创建 kube-controller-manager 的 systemd unit 文件

$ cat kube-controller-manager.service
[Unit]
Description=Kubernetes Controller Manager
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=kube-apiserver.service

[Service]
EnvironmentFile=-/etc/kubernetes/config
EnvironmentFile=-/etc/kubernetes/controller-manager
ExecStart=/usr/bin/kube-controller-manager \
        $KUBE_LOGTOSTDERR \
        $KUBE_LOG_LEVEL \
        $KUBE_MASTER \
        $KUBE_CONTROLLER_MANAGER_ARGS
Restart=on-failure
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

配置文件/etc/kubernetes/controller-manager

###
# The following values are used to configure the kubernetes controller-manager

# defaults from config and apiserver should be adequate

# Add your own!
KUBE_CONTROLLER_MANAGER_ARGS="--address=127.0.0.1 --service-cluster-ip-range=10.254.0.0/16 --cluster-name=kubernetes --cluster-signing-cert-file=/etc/kubernetes/ssl/ca.pem --cluster-signing-key-file=/etc/kubernetes/ssl/ca-key.pem  --service-account-private-key-file=/etc/kubernetes/ssl/ca-key.pem --root-ca-file=/etc/kubernetes/ssl/ca.pem --leader-elect=true"
  • --address 值必须为 127.0.0.1,因为当前 kube-apiserver 期望 scheduler 和 controller-manager 在同一台机器,否则:

      $ kubectl get componentstatuses
      NAME                 STATUS      MESSAGE                                                                                        ERROR
      controller-manager   Unhealthy   Get http://127.0.0.1:10252/healthz: dial tcp 127.0.0.1:10252: getsockopt: connection refused
      scheduler            Unhealthy   Get http://127.0.0.1:10251/healthz: dial tcp 127.0.0.1:10251: getsockopt: connection refused
    

    参考:https://github.com/kubernetes-incubator/bootkube/issues/64

  • --master=http://{MASTER_IP}:8080:使用非安全 8080 端口与 kube-apiserver 通信;

  • --cluster-cidr 指定 Cluster 中 Pod 的 CIDR 范围,该网段在各 Node 间必须路由可达(flanneld保证);
  • --service-cluster-ip-range 参数指定 Cluster 中 Service 的CIDR范围,该网络在各 Node 间必须路由不可达,必须和 kube-apiserver 中的参数一致;
  • --cluster-signing-* 指定的证书和私钥文件用来签名为 TLS BootStrap 创建的证书和私钥;
  • --root-ca-file 用来对 kube-apiserver 证书进行校验,指定该参数后,才会在Pod 容器的 ServiceAccount 中放置该 CA 证书文件
  • --leader-elect=true 部署多台机器组成的 master 集群时选举产生一处于工作状态的 kube-controller-manager 进程;

完整 unit 见 kube-controller-manager.service

启动 kube-controller-manager

$ sudo cp kube-controller-manager.service /etc/systemd/system/
$ sudo systemctl daemon-reload
$ sudo systemctl enable kube-controller-manager
$ sudo systemctl start kube-controller-manager
$

配置和启动 kube-scheduler

创建 kube-scheduler 的 systemd unit 文件

$ cat  kube-scheduler.service 
[Unit]
Description=Kubernetes Scheduler
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=kube-apiserver.service

[Service]
EnvironmentFile=-/etc/kubernetes/config
EnvironmentFile=-/etc/kubernetes/scheduler
ExecStart=/usr/bin/kube-scheduler \
            $KUBE_LOGTOSTDERR \
            $KUBE_LOG_LEVEL \
            $KUBE_MASTER \
            $KUBE_SCHEDULER_ARGS
Restart=on-failure
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target

配置文件/etc/kubernetes/scheduler。

###
# kubernetes scheduler config

# default config should be adequate

# Add your own!
KUBE_SCHEDULER_ARGS="--leader-elect=true --address=127.0.0.1"
  • --address 值必须为 127.0.0.1,因为当前 kube-apiserver 期望 scheduler 和 controller-manager 在同一台机器;
  • --master=http://{MASTER_IP}:8080:使用非安全 8080 端口与 kube-apiserver 通信;
  • --leader-elect=true 部署多台机器组成的 master 集群时选举产生一处于工作状态的 kube-controller-manager 进程;

完整 unit 见 kube-scheduler.service

启动 kube-scheduler

$ sudo cp kube-scheduler.service /etc/systemd/system/
$ sudo systemctl daemon-reload
$ sudo systemctl enable kube-scheduler
$ sudo systemctl start kube-scheduler
$

验证 master 节点功能

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

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