Build Kubernetes[k8s] cluster

准备工作

我是先对docker初步到进阶的了解学习,常用的命令,基本的容器构建和docker原理概念学习完之后,步入k8s。即使这样,刚看k8s官方文档时,其设计理念、组件构成以及生态需要了解掌握的知识不在少数。为此,花了几天时间在官方文档&个人博客上做了上述方面初步了解,较为直观的便可分为两方面:

master:

  • API server
  • Controller Manager
  • Scheduler
  • Etcd

node:

  • kublet
  • kube-proxy
  • pod

Kubernetes集群组件:

  • etcd 一个高可用的K/V键值对存储和服务发现系统
  • flannel 实现夸主机的容器网络的通信
  • kube-apiserver 提供kubernetes集群的API调用
  • kube-controller-manager 确保集群服务
  • kube-scheduler 调度容器,分配到Node
  • kubelet 在Node节点上按照配置文件中定义的容器规格启动容器
  • kube-proxy 提供网络代理服务

这些是在安装过程中直接接触的组件,了解其用途和原理会更胸有成竹吧。 若没有docker基础,应优先学习docker,在构建k8s时更易切解决碰到的问题。

搭建过程

官网给出的搭建流程不是很满意,会出问题,环境不同异常不同,排查起来需要用时间填坑;此外也有大量开发者给出的个人经验很有借鉴意义但也是有漏洞,或不详尽,或漏洞百出,需要读多篇这样的文章,相互比较找出漏洞形成完整的搭建思路才方便一部搭建到位,说简单也简单,复杂也是。


  • 环境:centos 7
  • ecs-ali2 master
  • ecs-ali3 node

因另外一台服务器负载较高,所以就搭建2个节点的集群,还是有别于但节点服务器的。3+节点的单间过程和此文相同,复制node搭建过程便可。


注意:如果你的服务器已经安装过docker,依据我的建议是应该卸载干净,不然会因kubernetes-node和docker产生冲突,导致node启动不了,找不到服务。

master环境搭建

关闭防火墙

我因使用的是iptables,在以前安装centos7时就变更了防火墙软件,不然建议先禁用centos7自带的Firewall

systemctl stop firewalld   master node环境各执行一遍
systemctl disable firewalld

确保epel源

yum -y install epel-release  master node环境各执行一遍

master安装etcd kubernetes-master

yum -y install etcd kubernetes-master

编辑/etc/etcd/etcd.conf文件

###
# 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=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=""
[root@ecs-ali2 kubernetes]# cat /etc/etcd/etcd.conf
#[Member]
#ETCD_CORS=""
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"     //在此
#ETCD_WAL_DIR=""
#ETCD_LISTEN_PEER_URLS="http://localhost:2380"
ETCD_LISTEN_CLIENT_URLS="http://0.0.0.0:2379"   //在此
#ETCD_MAX_SNAPSHOTS="5"
#ETCD_MAX_WALS="5"
ETCD_NAME="default"                             //在此
#ETCD_SNAPSHOT_COUNT="100000"
#ETCD_HEARTBEAT_INTERVAL="100"
#ETCD_ELECTION_TIMEOUT="1000"
#ETCD_QUOTA_BACKEND_BYTES="0"
#
#[Clustering]
#ETCD_INITIAL_ADVERTISE_PEER_URLS="http://localhost:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://ecs-ali2:2379"     //在此
#ETCD_DISCOVERY=""
#ETCD_DISCOVERY_FALLBACK="proxy"
#ETCD_DISCOVERY_PROXY=""
#ETCD_DISCOVERY_SRV=""
#ETCD_INITIAL_CLUSTER="default=http://localhost:2380"
#ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
#ETCD_INITIAL_CLUSTER_STATE="new"
#ETCD_STRICT_RECONFIG_CHECK="true"
#ETCD_ENABLE_V2="true"
#
#[Proxy]
#ETCD_PROXY="off"
#ETCD_PROXY_FAILURE_WAIT="5000"
#ETCD_PROXY_REFRESH_INTERVAL="30000"
#ETCD_PROXY_DIAL_TIMEOUT="1000"
#ETCD_PROXY_WRITE_TIMEOUT="5000"
#ETCD_PROXY_READ_TIMEOUT="0"
#
#[Security]
#ETCD_CERT_FILE=""
#ETCD_KEY_FILE=""
#ETCD_CLIENT_CERT_AUTH="false"
#ETCD_TRUSTED_CA_FILE=""
#ETCD_AUTO_TLS="false"
#ETCD_PEER_CERT_FILE=""
#ETCD_PEER_KEY_FILE=""
#ETCD_PEER_CLIENT_CERT_AUTH="false"
#ETCD_PEER_TRUSTED_CA_FILE=""
#ETCD_PEER_AUTO_TLS="false"
#
#[Logging]
#ETCD_DEBUG="false"
#ETCD_LOG_PACKAGE_LEVELS=""
#ETCD_LOG_OUTPUT="default"
#
#[Unsafe]
#ETCD_FORCE_NEW_CLUSTER="false"
#
#[Version]
#ETCD_VERSION="false"
#ETCD_AUTO_COMPACTION_RETENTION="0"
#
#[Profiling]
#ETCD_ENABLE_PPROF="false"
#ETCD_METRICS="basic"
#
#[Auth]
#ETCD_AUTH_TOKEN="simple"

编辑/etc/kubernetes/apiserver文件

###
# 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=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=""

启动etcd、kube-apiserver、kube-controller-manager、kube-scheduler等服务,并设置开机启动。

建议写一个脚本 kubernetes-master-start.sh每次执行脚本就好

#!/usr/bin/env bash  
for SERVICES in etcd kube-apiserver kube-controller-manager kube-scheduler; do
systemctl restart $SERVICES
systemctl enable $SERVICES
systemctl status $SERVICES
done

保存退出后执行下面命令增加可执行权限
chmod +x kubernetes-master-start.sh

etcd、kube-apiserver、kube-controller-manager、kube-scheduler等服务停止脚本

建议写一个脚本 kubernetes-master-end.sh每次执行脚本就好

#!/usr/bin/env bash

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

保存退出后执行下面命令增加可执行权限
chmod +x kubernetes-master-start.sh

执行后,service的status将会是active (running),否则将是空的,或者执行:

netstat -ntlp
若有
tcp        0      0 172.19.17.95:2380       0.0.0.0:*               LISTEN      25633/etcd
tcp6       0      0 :::10251                :::*                    LISTEN      25728/kube-schedule 
tcp6       0      0 :::6443                 :::*                    LISTEN      25667/kube-apiserve 
tcp6       0      0 :::2379                 :::*                    LISTEN      25633/etcd          
tcp6       0      0 :::10252                :::*                    LISTEN      25696/kube-controll 
tcp6       0      0 :::8080                 :::*                    LISTEN      25667/kube-apiserve

则恭喜你成了

在etcd中定义flannel网络

etcdctl mk /atomic.io/network/config '{"Network":"172.17.0.0/16"}

然后你可以访问master节点8080端口,将会返会json格式的节点环境数据!

node环境搭建

执行下面命令前,确认是否已经安装docker,若是则卸载,不然出问题,即使卸载后,kubernetes-node也会再次自动装上docker。

安装flannel和kubernetes-node

yum -y install flannel kubernetes-node

编辑/etc/etcd/etcd.conf文件

# Flanneld configuration options  

# etcd url location.  Point this to the server where etcd runs
FLANNEL_ETCD_ENDPOINTS="http://ecs-ali2:2379"

# etcd config key.  This is the configuration key that flannel queries
# For address range assignment
FLANNEL_ETCD_PREFIX="/atomic.io/network"

# Any additional options that you want to pass
#FLANNEL_OPTIONS=""

修改/etc/kubernetes/config文件

###
# 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=false"

# How the controller-manager, scheduler, and proxy find the apiserver
KUBE_MASTER="--master=http://ecs-ali2:8080"

在所有Node节点上启动kube-proxy,kubelet,docker,flanneld等服务,并设置开机启动

建议写一个脚本 kubernetes-node-start.sh每次执行脚本就好

#!/usr/bin/env bash

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

保存退出后执行下面命令增加可执行权限
chmod +x kubernetes-master-start.sh

结束kube-proxy,kubelet,docker,flanneld等服务

建议写一个脚本 kubernetes-node-start.sh每次执行脚本就好

#!/usr/bin/env bash
for SERVICES in kube-proxy kubelet docker; do
systemctl stop $SERVICES
systemctl status $SERVICES
done

保存退出后执行下面命令增加可执行权限
chmod +x kubernetes-master-start.sh

执行后,service的status将会是active (running),否则将是空的,或者执行:

netstat -ntlp
若有
tcp        0      0 127.0.0.1:10248         0.0.0.0:*               LISTEN      14484/kubelet       
tcp        0      0 127.0.0.1:10249         0.0.0.0:*               LISTEN      14080/kube-proxy
tcp6       0      0 :::10250                :::*                    LISTEN      14484/kubelet       
tcp6       0      0 :::10255                :::*                    LISTEN      14484/kubelet       
tcp6       0      0 :::4194                 :::*                    LISTEN      14484/kubelet

则恭喜你成了

集群环境验证

在master上执行如下命令

kubectl get node

我的是
[root@ecs-ali2 yum.repos.d]# kubectl get node
NAME       STATUS    AGE
ecs-ali3   Ready     1h

状态为Ready则说明集群搭建成功

官方文档采坑点

https://www.kubernetes.org.cn/doc-16,若是参考这个,以下是一些碰到的问题: 在添加添加virt7-testing源,其使用下面信息添加源:

[virt7-testing]
name=virt7-testing
baseurl=http://cbs.centos.org/repos/virt7-testing/x86_64/os/
gpgcheck=0

然后安转过程提示:

failure: repodata/repomd.xml from virt7-testing: [Errno 256] No more mirrors to try.
http://cbs.centos.org/repos/virt7-testing/x86_64/os/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found

解决办法: 替换baseurl

baseurl=http://cbs.centos.org/repos/virt7-docker-common-candidate/x86_64/os/

反正照着官方汉化文档我没有成功,应该不是我智商着急的原因!

参考文档

热情洋溢的程序员欢迎您以任何形式转载!