Kubernetes高可用Master节点安装

素颜马尾好姑娘i 2022-06-16 06:43 192阅读 0赞

## 前言 ##

这是[和我一步步部署kubernetes集群][kubernetes]项目((fork自[opsnull][]))中的一篇文章，下文是结合我[之前部署kubernetes的过程][kubernetes 1]产生的[kuberentes][]环境，部署master节点的`kube-apiserver`、`kube-controller-manager`和`kube-scheduler`的过程。

## 高可用Kubernetes Master节点安装 ##

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）

## TLS 证书文件 ##

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

$ 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][github release] 下载发布版 tarball，解压后再执行下载脚本

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

方式二

从 [`CHANGELOG`页面][CHANGELOG] 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；

$ # 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

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

[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://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：

### ## 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://172.20.0.113:2379,172.20.0.114:2379,172.20.0.115:2379" # ## 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][]

启动kube-apiserver

$ 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`

Description=Kubernetes Controller Manager Documentation=https://github.com/GoogleCloudPlatform/kubernetes [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"

*  `--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：

$ 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 Unhealthy Get http://172.20.0.113:2379/health: malformed HTTP response "\x15\x03\x01\x00\x02\x02" etcd-0 Healthy { "health": "true"} etcd-1 Healthy { "health": "true"}

参考：[https://github.com/kubernetes-incubator/bootkube/issues/64][https_github.com_kubernetes-incubator_bootkube_issues_64]

完整 unit 见 [kube-controller-manager.service][]

### 启动 Kube-Controller-Manager ###

$ 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.serivce`。

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

完整 unit 见 [kube-scheduler.service][]

### 启动 Kube-Scheduler ###

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

## 验证 Master 节点功能 ##

$ 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"}

## 后记 ##

当时在配置过程中遇到了问题[TLS认证相关的问题][TLS 1]，其实就是因为配置apiserver时候etcd的协议写成了http导致的，应该是用https。

[Opsnull][opsnull]写的kubernetes高可用master集群部署过程中似乎并没有包括高可用的配置，才云科技的唐继元分享过[Kubernetes Master High Availability 高级实践][Kubernetes Master High Availability]。

究竟如何实现kubernetes master的高可用还需要继续探索。

原文：Kubernetes中文社区  [Kubernetes高可用Master节点安装][Kubernetes_Master]

[kubernetes]: https://github.com/rootsongjc/follow-me-install-kubernetes-cluster
[opsnull]: https://github.com/opsnull/follow-me-install-kubernetes-cluster
[kubernetes 1]: http://rootsongjc.github.io/tags/kubernetes/
[kuberentes]: https://www.kubernetes.org.cn
[TLS]: http://rootsongjc.github.io/01-TLS%E8%AF%81%E4%B9%A6%E5%92%8C%E7%A7%98%E9%92%A5.md
[github release]: https://github.com/kubernetes/kubernetes/releases
[CHANGELOG]: https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG.md
[kube-apiserver.service]: http://rootsongjc.github.io/systemd/kube-apiserver.service
[https_github.com_kubernetes-incubator_bootkube_issues_64]: https://github.com/kubernetes-incubator/bootkube/issues/64
[kube-controller-manager.service]: http://rootsongjc.github.io/systemd/kube-controller-manager.service
[kube-scheduler.service]: http://rootsongjc.github.io/systemd/kube-scheduler.service
[TLS 1]: https://github.com/opsnull/follow-me-install-kubernetes-cluster/issues/4
[Kubernetes Master High Availability]: https://segmentfault.com/a/1190000005832319
[Kubernetes_Master]: https://www.kubernetes.org.cn/1865.html