kubernetes-handbook/05-部署高可用master集群.md

# 部署高可用 kubernetes master 集群

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-scheduler`、`kube-controller-manager` 和 `kube-apiserver` 三者的功能紧密相关；
+ 同时只能有一个 `kube-scheduler`、`kube-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；

~~本文档记录部署一个三个节点的高可用 kubernetes master 集群步骤。（后续创建一个 load balancer 来代理访问 kube-apiserver 的请求）~~

暂时未实现master节点的高可用。

## TLS 证书文件

pem和token.csv证书文件我们在[TLS证书和秘钥](./01-TLS证书和秘钥.md)这一步中已经创建过了。我们再检查一下。

``` bash
$ ls /etc/kubernetes/ssl
admin-key.pem  admin.pem  ca-key.pem  ca.pem  kube-proxy-key.pem  kube-proxy.pem  kubernetes-key.pem  kubernetes.pem
```

## 下载最新版本的二进制文件

有两种下载方式

**方式一**

从 [github release 页面](https://github.com/kubernetes/kubernetes/releases) 下载发布版 tarball，解压后再执行下载脚本

``` shell
$ wget https://github.com/kubernetes/kubernetes/releases/download/v1.6.0/kubernetes.tar.gz
$ tar -xzvf kubernetes.tar.gz
...
$ cd kubernetes
$ ./cluster/get-kube-binaries.sh
...
```
**方式二**

从 [`CHANGELOG`页面](https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG.md) 下载 `client` 或 `server` 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；

``` shell
$ # wget https://dl.k8s.io/v1.6.0/kubernetes-client-linux-amd64.tar.gz
$ wget https://dl.k8s.io/v1.6.0/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

``` bash
$ cp -r server/bin/{kube-apiserver,kube-controller-manager,kube-scheduler,kubectl,kube-proxy,kubelet} /usr/local/bin/
```

## 配置和启动 kube-apiserver

**创建 kube-apiserver的service配置文件**

serivce配置文件`/usr/lib/systemd/system/kube-apiserver.service`内容：

```ini
[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/local/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：

```ini
###
# 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://sz-pg-oam-docker-test-001.tendcloud.com:8080"
KUBE_MASTER="--master=http://172.20.0.113:8080"
```

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：

``` Ini
###
## 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=172.20.0.113 --bind-address=172.20.0.113 --insecure-bind-address=172.20.0.113"
#
## 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://172.20.0.113:2379,https://172.20.0.114:2379,https://172.20.0.115:2379"
#
## 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"
```

+ `--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` 和 `--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`；
+ `--bind-address` 不能为 `127.0.0.1`；
+ `runtime-config`配置为`rbac.authorization.k8s.io/v1beta1`，表示运行时的apiVersion；
+ `--service-cluster-ip-range` 指定 Service Cluster IP 地址段，该地址段不能路由可达；
+ 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](./systemd/kube-apiserver.service)

**启动kube-apiserver**

``` bash
$ systemctl daemon-reload
$ systemctl enable kube-apiserver
$ systemctl start kube-apiserver
$ systemctl status kube-apiserver
```

## 配置和启动 kube-controller-manager

**创建 kube-controller-manager的serivce配置文件**

文件路径`/usr/lib/systemd/system/kube-controller-manager.service`

```ini
Description=Kubernetes Controller Manager
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
EnvironmentFile=-/etc/kubernetes/config
EnvironmentFile=-/etc/kubernetes/controller-manager
ExecStart=/usr/local/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`。

``` ini
###
# 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"
```

+ `--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**；
+ `--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：

    ``` bash
    $ kubectl 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   Healthy     ok                                                                                             
    etcd-2               Healthy     {"health": "true"} 
    etcd-0               Healthy     {"health": "true"}                                                                             
    etcd-1               Healthy     {"health": "true"}  
    ```

    如果有组件report unhealthy请参考：https://github.com/kubernetes-incubator/bootkube/issues/64

完整 unit 见 [kube-controller-manager.service](./systemd/kube-controller-manager.service)

### 启动 kube-controller-manager

``` bash
$ systemctl daemon-reload
$ systemctl enable kube-controller-manager
$ systemctl start kube-controller-manager
```

## 配置和启动 kube-scheduler

**创建 kube-scheduler的serivce配置文件**

文件路径`/usr/lib/systemd/system/kube-scheduler.service`。

```ini
[Unit]
Description=Kubernetes Scheduler Plugin
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
EnvironmentFile=-/etc/kubernetes/config
EnvironmentFile=-/etc/kubernetes/scheduler
ExecStart=/usr/local/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`。

``` Ini
###
# 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；

完整 unit 见 [kube-scheduler.service](./systemd/kube-scheduler.service)

### 启动 kube-scheduler

``` bash
$ systemctl daemon-reload
$ systemctl enable kube-scheduler
$ systemctl start kube-scheduler
```

## 验证 master 节点功能

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