在之前一篇使用nginx搭建高可用的解決方案的時候，很多同學會問，如果nginx掛掉怎麼辦，比如下面這張圖：
你可以清楚的看到，如果192.168.2.100這臺機器掛掉了，那麼整個叢集就下線了，這個問題該怎麼解決呢？？？ 簡單的想想確實不大好處理，因為你
的webBrowser總得要訪問一個ip地址，對吧。。這個問題怎麼破呢？
一：問題分析
如果你有一些網路底子的話，就會明白，你給一個不在本網段的機器傳送請求的話，這個請求會先經過你的閘道器IP，然後通過閘道器IP傳給對方的閘道器IP，然
後閘道器IP會將請求轉給它所在區域網的主機，當然我的閘道器IP和對方的閘道器IP之間可能有很多跳的路由地址，大概的流程就是下面這樣：
如果你不信的話，可以用tracert 看看你到www.ctrip.com的路由總過程。
從上圖中可以看到，從我當前主機到ctrip.com一共有20跳，第一條是192.168.2.1，這個就是我的路由器IP，也就是我的閘道器IP。
二：虛擬路由冗餘協議
好了，說了這麼多有什麼用呢？其實大家仔細觀察這張圖，你會想我能不能在閘道器IP上做一些手腳呢？ 可喜的是如今的路由器基本上都支援一個叫做
VRRP（虛擬路由冗餘協議），這一協議的作用你可以理解成把閘道器IP虛擬化成一個閘道器IP叢集，就好像獸族劍聖的映象技能，這裡面有master，也有slave，
然後區域網內的主機設定的都是虛擬的masterIP（VIP），剛好keepealived就是一個實現VRRP的一款應用程式，你需要，我專業，大家就這樣走到一塊了。
三：keepalived搭建一覽
1. 下載：從官網上找到當前最新的版本1.4.2。http://www.keepalived.org/software/keepalived-1.4.2.tar.gz。
配置機器： 192.168.23.156 【centos】
192.168.23.157 【centos】
1 [root@localhost app]# wget http://www.keepalived.org/software/keepalived-1.4.2.tar.gz 2 --2018-03-10 04:04:06-- http://www.keepalived.org/software/keepalived-1.4.2.tar.gz 3 Resolving www.keepalived.org (www.keepalived.org)... 37.59.63.157, 2001:41d0:8:7a9d::1 4 Connecting to www.keepalived.org (www.keepalived.org)|37.59.63.157|:80... connected. 5 HTTP request sent, awaiting response... 200 OK 6 Length: 738096 (721K) [application/x-gzip] 7 Saving to: ‘keepalived-1.4.2.tar.gz’ 8 9 100%[==================================================================>] 738,096 5.24KB/s in 4m 44s
2. 然後把相關依賴裝起來：yum install -y openssl openssl-devel。
1 [root@localhost app]# yum install -y openssl openssl-devel 2 Loaded plugins: fastestmirror, langpacks 3 Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was 4 14: curl#52 - "Empty reply from server" 5 base | 3.6 kB 00:00:00 6 epel/x86_64/metalink | 7.8 kB 00:00:00 7 Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=extras&infra=stock error was 8 14: curl#52 - "Empty reply from server" 9 extras | 3.4 kB 00:00:00 10 updates | 3.4 kB 00:00:00 11 updates/7/x86_64/primary_db | 6.9 MB 00:01:10
3. 接下來繼續解壓，最後安裝三板斧： ./configure --prefix=/usr/app/keepalived && make && make install。
[root@localhost app]# tar -zxvf keepalived-1.4.2.tar.gz [root@localhost app]# ls keepalived-1.4.2 keepalived-1.4.2.tar.gz [root@localhost app]# cd keepalived-1.4.2 [root@localhost keepalived-1.4.2]# ls aclocal.m4 bin_install configure COPYING genhash keepalived Makefile.am README.md ar-lib ChangeLog configure.ac depcomp INSTALL keepalived.spec.in Makefile.in snap AUTHOR compile CONTRIBUTORS doc install-sh lib missing TODO [root@localhost keepalived-1.4.2]#
[root@localhost keepalived-1.4.2]# ./configure --prefix=/usr/app/keepalived && make && make install
安裝好了之後，你就會看到如下的內容，那就恭喜你，安裝成功了。
Keepalived configuration ------------------------ Keepalived version : 1.4.2 Compiler : gcc Preprocessor flags : Compiler flags : -Wall -Wunused -Wstrict-prototypes -Wextra -g -O2 -fPIE -D_GNU_SOURCE Linker flags : -pie Extra Lib : -lcrypto -lssl Use IPVS Framework : Yes IPVS use libnl : No IPVS syncd attributes : No IPVS 64 bit stats : No fwmark socket support : Yes Use VRRP Framework : Yes Use VRRP VMAC : Yes Use VRRP authentication : Yes With ip rules/routes : Yes SNMP vrrp support : No SNMP checker support : No SNMP RFCv2 support : No SNMP RFCv3 support : No DBUS support : No SHA1 support : No Use Debug flags : No smtp-alert debugging : No Use Json output : No Stacktrace support : No Memory alloc check : No libnl version : None Use IPv4 devconf : No Use libiptc : No Use libipset : No init type : systemd Build genhash : Yes Build documentation : No
4. 安裝好了之後，在/usr/app/keepalived/etc/keepalived目錄下有一個keepalived.conf檔案，現在你要做的事情就是
將它copy到/etc/keepalived資料夾下就可以了。
1 [root@localhost keepalived]# ls 2 keepalived.conf samples 3 [root@localhost keepalived]# pwd 4 /usr/app/keepalived/etc/keepalived 5 [root@localhost keepalived]# mkdir -p /etc/keepalived 6 [root@localhost keepalived]# cp ./keepalived.conf /etc/keepalived/keepalived.conf
5. 接下來我們改一下配置檔案。
在192.168.23.156機器中的配置檔案，修改如下：
【原來】
global_defs { notification_email { acassen@firewall.loc failover@firewall.loc sysadmin@firewall.loc } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 192.168.200.1 smtp_connect_timeout 30 router_id LVS_DEVEL vrrp_skip_check_adv_addr vrrp_strict vrrp_garp_interval 0 vrrp_gna_interval 0 } vrrp_instance VI_1 { state MASTER interface eth0 virtual_router_id 51 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.200.16 192.168.200.17 192.168.200.18 } }
【修改】
global_defs { notification_email { acassen@firewall.loc failover@firewall.loc sysadmin@firewall.loc } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 192.168.200.1 smtp_connect_timeout 30 router_id NodeA vrrp_skip_check_adv_addr vrrp_strict vrrp_garp_interval 0 vrrp_gna_interval 0 } vrrp_instance VI_1 { state MASTER interface ens33 virtual_router_id 51 priority 150 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.2.200 } }
其中要注意的就是：
《1》priority 150
節點的優先順序，master要比slave高。
《2》interface ens33
ens33大家可以通過ipconfig檢視一下自己的網路卡。
[root@localhost ~]# ifconfig br-11757db6abf5: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 172.22.0.1 netmask 255.255.0.0 broadcast 0.0.0.0 ether 02:42:c2:e0:52:10 txqueuelen 0 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 br-875e3c64ec79: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 172.23.0.1 netmask 255.255.0.0 broadcast 0.0.0.0 ether 02:42:4e:43:5b:a0 txqueuelen 0 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 br-904f2c62861e: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 172.19.0.1 netmask 255.255.0.0 broadcast 0.0.0.0 ether 02:42:6d:80:36:58 txqueuelen 0 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 br-b0028a425959: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 172.21.0.1 netmask 255.255.0.0 broadcast 0.0.0.0 ether 02:42:68:51:95:99 txqueuelen 0 (Ethernet) RX packets 18 bytes 1458 (1.4 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 41 bytes 3920 (3.8 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 br-c4a09a75fc67: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 172.18.0.1 netmask 255.255.0.0 broadcast 0.0.0.0 ether 02:42:92:f9:2d:65 txqueuelen 0 (Ethernet) RX packets 4 bytes 340 (340.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 4 bytes 340 (340.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 br-f0fb207788a0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 172.20.0.1 netmask 255.255.0.0 broadcast 0.0.0.0 inet6 fe80::42:86ff:fe1e:c970 prefixlen 64 scopeid 0x20<link> ether 02:42:86:1e:c9:70 txqueuelen 0 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 172.17.0.1 netmask 255.255.0.0 broadcast 0.0.0.0 ether 02:42:8f:8c:a9:a7 txqueuelen 0 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.23.157 netmask 255.255.255.0 broadcast 192.168.23.255 inet6 fe80::20c:29ff:fe54:4f5a prefixlen 64 scopeid 0x20<link> ether 00:0c:29:54:4f:5a txqueuelen 1000 (Ethernet) RX packets 10899 bytes 11349012 (10.8 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 5575 bytes 599717 (585.6 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10<host> loop txqueuelen 0 (Local Loopback) RX packets 4 bytes 340 (340.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 4 bytes 340 (340.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 veth4d72ad4: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet6 fe80::d4fb:fcff:feeb:cd7c prefixlen 64 scopeid 0x20<link> ether d6:fb:fc:eb:cd:7c txqueuelen 0 (Ethernet) RX packets 16 bytes 1248 (1.2 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 43 bytes 4130 (4.0 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 vethe634b1c: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet6 fe80::e0c6:88ff:fe1c:f4a1 prefixlen 64 scopeid 0x20<link> ether e2:c6:88:1c:f4:a1 txqueuelen 0 (Ethernet) RX packets 18 bytes 1458 (1.4 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 41 bytes 3920 (3.8 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 00:00:00:00:00:00 txqueuelen 0 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [root@localhost ~]#
《3》virtual_ipaddress 192.168.23.200
設定好虛擬IP（VIP）為：192.168.23.200
同樣的道理，在192.168.23.157設定如下：
global_defs { notification_email { acassen@firewall.loc failover@firewall.loc sysadmin@firewall.loc } notification_email_from Alexandre.Cassen@firewall.loc smtp_server 192.168.200.1 smtp_connect_timeout 30 router_id NodeB vrrp_skip_check_adv_addr vrrp_strict vrrp_garp_interval 0 vrrp_gna_interval 0 } vrrp_instance VI_1 { state BACKUP interface ens33 virtual_router_id 51 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.23.200 } }
7. 接下來就可以啟動keepalived了。
[root@localhost sbin]# ./keepalived -D [root@localhost sbin]# ps -ef | grep keepalived root 4661 1 0 05:41 ? 00:00:00 ./keepalived -D root 4662 4661 0 05:41 ? 00:00:00 ./keepalived -D root 4663 4661 0 05:41 ? 00:00:00 ./keepalived -D root 4673 4300 0 05:41 pts/0 00:00:00 grep --color=auto keepalived
五：檢測
1. 通過ip a 看看當前ens33網路卡上是否繫結了192.168.23.200虛擬IP。
2. 然後通過arp -a 檢視當前的vip對映到的物理(mac)地址，可以看到當前的vip對映到的是192.168.23.156上面。
C:\Users\hxc>arp -a 介面: 192.168.23.1 --- 0x6 Internet 地址 實體地址 型別 192.168.23.156 00-0c-29-75-7e-20 動態 192.168.23.157 00-0c-29-54-4f-5a 動態 192.168.23.200 00-0c-29-75-7e-20 動態 192.168.23.255 ff-ff-ff-ff-ff-ff 靜態 224.0.0.22 01-00-5e-00-00-16 靜態 224.0.0.251 01-00-5e-00-00-fb 靜態 224.0.0.252 01-00-5e-00-00-fc 靜態 239.11.20.1 01-00-5e-0b-14-01 靜態 239.255.255.250 01-00-5e-7f-ff-fa 靜態 255.255.255.255 ff-ff-ff-ff-ff-ff 靜態
3. 然後我們把156這臺機器關閉了，可以看到當前的vip已經漂移到了157這臺機器上了。
C:\Users\hxc>arp -a 介面: 192.168.23.1 --- 0x6 Internet 地址 實體地址 型別 192.168.23.156 00-0c-29-75-7e-20 動態 192.168.23.157 00-0c-29-54-4f-5a 動態 192.168.23.200 00-0c-29-54-4f-5a 動態 192.168.23.255 ff-ff-ff-ff-ff-ff 靜態 224.0.0.22 01-00-5e-00-00-16 靜態 224.0.0.251 01-00-5e-00-00-fb 靜態 224.0.0.252 01-00-5e-00-00-fc 靜態 239.11.20.1 01-00-5e-0b-14-01 靜態 239.255.255.250 01-00-5e-7f-ff-fa 靜態 255.255.255.255 ff-ff-ff-ff-ff-ff 靜態
好了，這個就是本篇所說的所有內容，希望對您有幫助。