集群介紹

根據(jù)功能劃分為兩大類：高可用和負(fù)載均衡?高可用集群通常為兩臺(tái)服務(wù)器，一臺(tái)工作，另外一臺(tái)作為冗余，當(dāng)提供服務(wù)的機(jī)器宕機(jī)，冗余將接替繼續(xù)提供服務(wù)?實(shí)現(xiàn)高可用的開(kāi)源軟件有：heartbeat、keepalived?負(fù)載均衡集群，需要有一臺(tái)服務(wù)器作為分發(fā)器，它負(fù)責(zé)把用戶的請(qǐng)求分發(fā)給后端的服務(wù)器處理，在這個(gè)集群里，除了分發(fā)器外，就是給用戶提供服務(wù)的服務(wù)器了，這些服務(wù)器數(shù)量至少為2?實(shí)現(xiàn)負(fù)載均衡的開(kāi)源軟件有LVS、keepalived、haproxy、nginx，商業(yè)的有F5、Netscaler

Keepalive介紹（HA集群）HA即高可用，又叫做雙機(jī)熱備，用于關(guān)鍵性的業(yè)務(wù)，簡(jiǎn)單理解就是有兩臺(tái)機(jī)器A和B，正常是A提供服務(wù)，B待命閑置，當(dāng)A宕機(jī)或者服務(wù)宕掉，會(huì)切換至B機(jī)器繼續(xù)提供服務(wù)。在這里我們使用keepalived來(lái)實(shí)現(xiàn)高可用集群，因?yàn)閔eartbeat在centos6上有一些問(wèn)題，影響實(shí)驗(yàn)效果??keepalived通過(guò)VRRP（Virtual?Router?Redundancy?Protocl）來(lái)實(shí)現(xiàn)高可用。?在這個(gè)協(xié)議里會(huì)將多臺(tái)功能相同的路由器組成一個(gè)小組，這個(gè)小組里會(huì)有1個(gè)master角色和N（N>=1）個(gè)backup角色。?master會(huì)通過(guò)組播的形式向各個(gè)backup發(fā)送VRRP協(xié)議的數(shù)據(jù)包，當(dāng)backup收不到master發(fā)來(lái)的VRRP數(shù)據(jù)包時(shí)，就會(huì)認(rèn)為master宕機(jī)了。此時(shí)就需要根據(jù)各個(gè)backup的優(yōu)先級(jí)來(lái)決定誰(shuí)成為新的mater。?Keepalived要有三個(gè)模塊，分別是core、check和vrrp。其中core模塊為keepalived的核心，負(fù)責(zé)主進(jìn)程的啟動(dòng)、維護(hù)以及全局配置文件的加載和解析，check模塊負(fù)責(zé)健康檢查，vrrp模塊是來(lái)實(shí)現(xiàn)VRRP協(xié)議的。

用keepalived配置高可用集群keepalived下需要有一個(gè)服務(wù)來(lái)實(shí)現(xiàn)高可用，用nginx來(lái)代替實(shí)現(xiàn)服務(wù)準(zhǔn)備兩臺(tái)機(jī)器130和132，130作為master，132作為backup?兩臺(tái)機(jī)器都執(zhí)行yum?install?-y?keepalived?兩臺(tái)機(jī)器都安裝nginx，其中130上已經(jīng)編譯安裝過(guò)nginx，132上需要yum安裝nginx:?yum?install?-y?nginx

設(shè)定vip為100#vim?/etc/keepalived/keepalived.conf?編輯130上keepalived配置文件，內(nèi)容從https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/master_keepalived.conf獲取? 先清空原先配置文件的內(nèi)容，用快捷鍵>!$，然后再將復(fù)制的文件放到#/etc/keepalived/keepalived.conf下

global_defs?{????????????????? notification_email?{????????????//可以不用定義aming@aminglinux.com } notification_email_from?root@aminglinux.com smtp_server?127.0.0.1 smtp_connect_timeout?30router_id?LVS_DEVEL } vrrp_script?chk_nginx?{????????//檢測(cè)服務(wù)是否正常script?"/usr/local/sbin/check_ng.sh"?????//定義腳本路徑interval?3} vrrp_instance?VI_1?{ state?MASTERinterface?ens33virtual_router_id?51??????//主從id一致priority?100???????//權(quán)重advert_int?1authentication?{ auth_type?PASS auth_pass?aminglinux>com } virtual_ipaddress?{192.168.37.100 } track_script?{ chk_nginx } }#vim?/usr/local/sbin/check_ng.sh130編輯監(jiān)控腳本，內(nèi)容從https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/master_check_ng.sh獲取#!/bin/bash#時(shí)間變量，用于記錄日志d=`date?--date?today?+%Y%m%d_%H:%M:%S`#計(jì)算nginx進(jìn)程數(shù)量n=`ps?-C?nginx?--no-heading|wc?-l`#如果進(jìn)程為0，則啟動(dòng)nginx，并且再次檢測(cè)nginx進(jìn)程數(shù)量，#如果還為0，說(shuō)明nginx無(wú)法啟動(dòng)，此時(shí)需要關(guān)閉keepalivedif?[?$n?-eq?"0"?];?then/etc/init.d/nginx?start n2=`ps?-C?nginx?--no-heading|wc?-l`if?[?$n2?-eq?"0"?];?thenecho?"$d?nginx?down,keepalived?will?stop"?>>?/var/log/check_ng.log systemctl?stop?keepalivedfifi#chmod?755?/usr/local/sbin/check_ng.sh????????????????//給腳本755權(quán)限#systemctl?start??keepalived????????????//master上啟動(dòng)keepalived服務(wù)132上#vim?/etc/keepalived/keepalived.conf?????編輯配置文件，內(nèi)容從https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/backup_keepalived.conf獲取global_defs?{ notification_email?{ aming@aminglinux.com } notification_email_from?root@aminglinux.com smtp_server?127.0.0.1 smtp_connect_timeout?30router_id?LVS_DEVEL } vrrp_script?chk_nginx?{ script?"/usr/local/sbin/check_ng.sh"interval?3} vrrp_instance?VI_1?{ state?BACKUPinterface?ens33virtual_router_id?51priority?90?????????????//權(quán)重advert_int?1authentication?{ auth_type?PASS auth_pass?aminglinux>com } virtual_ipaddress?{192.168.37.100 } track_script?{ chk_nginx } }132上編輯監(jiān)控腳本，內(nèi)容從https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/backup_check_ng.sh獲取#時(shí)間變量，用于記錄日志d=`date?--date?today?+%Y%m%d_%H:%M:%S`#計(jì)算nginx進(jìn)程數(shù)量n=`ps?-C?nginx?--no-heading|wc?-l`#如果進(jìn)程為0，則啟動(dòng)nginx，并且再次檢測(cè)nginx進(jìn)程數(shù)量，#如果還為0，說(shuō)明nginx無(wú)法啟動(dòng)，此時(shí)需要關(guān)閉keepalivedif?[?$n?-eq?"0"?];?thensystemctl?start?nginx n2=`ps?-C?nginx?--no-heading|wc?-l`if?[?$n2?-eq?"0"?];?thenecho?"$d?nginx?down,keepalived?will?stop"?>>?/var/log/check_ng.log systemctl?stop?keepalivedfifi#chmod?755?/usr/local/sbin/check_ng.sh????????????//給腳本755權(quán)限132上也啟動(dòng)服務(wù)?#systemctl?start?keepalived模擬之前先要關(guān)閉防火墻和selinux， 模擬生產(chǎn)環(huán)境中宕機(jī)的情況，測(cè)試高可用： 最好的手段是關(guān)閉主上的keepalived服務(wù)來(lái)測(cè)試高可用

轉(zhuǎn)載于:https://blog.51cto.com/simonhu/2073412

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