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keepalived_nginx实现discuz负载均衡和高可用

2016-05-29 20:44 786 查看
前言:

上回讲到,《lvs-dr模型负载均衡高可用Discuz》,但是由于lvs过于重量级,小公司使用有点不合时宜,本回咱们使用nginx实现此功能。望各位博友笑纳。

此次试验使用nginx代替lvs作为前端调度器,使用keepalived对nginx做双主模型高可用,向后做反向代理。RS服务器使用httpd+php来处理php页面请求,httpd和php以模块形式结合。暂时不考虑会话保持和动静资源分离的问题。我们下一篇博客会做补充。一次写太多会影响品质!!!

规划:
前端使用两台nginx服务器作为前端调度器,使用keepalived对nginx做双主模型高可用,两台RS服务器,后端一台共享存储提供mariadb和NFS服务,因为不再使用LVS调度,而是通过nginx反代来实现,所以两台RS服务器不需要在本地回环接口的别名上配置VIP

各个主机的IP地址Host VS1 eno16777736 10.0.0.201/8 (DIP)
gateway: 10.0.0.254

Host VS2 eno16777736 10.0.0.203/8(DIP)
gateway: 10.0.0.254
Host RS1 eno16777736 10.0.0.101/8 (RIP1) gateway: 10.0.0.254 Host RS2 eno16777736 10.0.0.102/8 (RIP2) gateway: 10.0.0.254
Host DB eno16777736 10.0.0.202/8
gateway: 10.0.0.254

时间同步:
# ntpdate cn.pool.ntp.org
# hwclock --sysohc

安装软件:HostDB

安装二进制mariadb-5.5.46详细配置请入传送门:http://wscto.blog.51cto.com/11249394/1783131
安装NFS
# yum install -y nfs-utils

HostRS1安装nginx,注意nginx属于epel源
# yum install-y nginx php-fpm php-mbstring php-mysql nfs-utils mariadb

HostRS2安装nginx,注意nginx属于epel源
# yum install-y nginx php-fpm php-mbstring php-mysql nfs-utils mariadb

Host VS1安装keepalived是为了实现高可用,nginx实现反代 nfs-utils
# yum install -y keepalived nfs-utils
#  wget http://nginx.org/packages/centos/6/x86_64/RPMS/nginx-1.8.1-1.el6.ngx.x86_64.rpm #  rpm -ivh nginx-1.8.1-1.el6.ngx.x86_64.rpm
注意:CentOS 6中nginx版本,比较低,所以可以这样下载,在7中无需考虑Host VS2安装keepalived是为了实现高可用,nginx实现反代 nfs-utils
# yum install -y keepalived nfs-utils
#  wget http://nginx.org/packages/centos/6/x86_64/RPMS/nginx-1.8.1-1.el6.ngx.x86_64.rpm #  rpm -ivh nginx-1.8.1-1.el6.ngx.x86_64.rpm

HostDB完成安全初始化后,创建discuz数据库和discuz用户,并授权其可以远程操作数据库
# mysql_secure_installation
# mysql -u root -p
Enter password:
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 5.5.46-MariaDB-log MariaDB Server

Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> create database discuz;
Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> create user 'discuz'@'localhost' identified by 'magedu';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> grant all privileges on discuz.* to 'discuz'@'%' identified by 'magedu';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

配置NFS
# mkdir /nfshare/
# ls -dl /nfshare/
drwxr-xr-x 2 root root 6 May 9 17:01 /nfshare/
# echo "/nfshare/ 10.0.0.101(rw,no_root_squash,async) 10.0.0.102(rw,no_root_squash,async)" > /etc/exports
# systemctl start rpcbind   <--如果是CentOS-6要使用/etc/init.d/rpcbind start
Starting rpcbind:                                          [  OK  ]
[root@34400575 ~]# /etc/init.d/nfs start
Starting NFS services:                                     [  OK  ]
Starting NFS quotas:                                       [  OK  ]
Starting NFS mountd:                                       [  OK  ]
Starting NFS daemon:                                       [  OK  ]
Starting RPC idmapd:                                       [  OK  ]
# systemctl enable rpcbind  <--如果是6 chkconfig rpcbind on
# systemctl enable rpcbind  <--如果是6 chkconfig nfs on
[root@34400575 ~]# chkconfig rpcbind --list
rpcbind            0:off    1:off    2:on    3:on    4:on    5:on    6:off
[root@34400575 ~]# chkconfig nfs --list
nfs                0:off    1:off    2:on    3:on    4:on    5:on    6:off
[root@34400575 ~]# showmount -e 127.0.0.1
Export list for 127.0.0.1:
/nfshare 172.18.71.102,172.18.71.101    此步骤如果出现问题,请查看《lvs-dr负载均衡Discuz》

解压discuz的程序包至/nfsshare/目录
# mkdir /nfshare/discuz
# unzip /Discuz_X3.2_SC_UTF8.zip -d /nfshare/discuz/
# ls /nfshare/discuz/
readme  upload  utility
Host RS1

测试链接HostDB上的mariadb
# mysql -h 10.0.0.202 -u discuz -p

挂载HostDB上的NFS共享存储目录,属主属组改为apache
# showmount -e 10.0.0.202
Export list for 10.0.0.202:
/nfshare 10.0.0.102,10.0.0.101
[root@b9cf468b ~]# mkdir /htdocs
[root@b9cf468b ~]# ls -ld /htdocs/
drwxr-xr-x 2 root root 6 May 9 17:05 /htdocs/
[root@b9cf468b ~]# mount -t nfs 10.0.0.202:/nfshare /htdocs
[root@b9cf468b ~]# ls /htdocs/
discuz
[root@b9cf468b ~]# chown -R apache:apache /htdocs/discuz/

配置httpd,测试没有语法错误,启动httpd
# vim /etc/httpd/conf.d/vhosts.conf
...
<VirtualHost *:80>
ServerName admin.ws.com
DocumentRoot "/htdocs/discuz/upload/"
<Directory "/htdocs/discuz/upload/">
Options Indexes FollowSymLinks
AllowOverride None
Require all granted
</Directory>
</VirtualHost>
# systemctl start httpd.service
# ss -tnl | grep 80
LISTEN     0      128         :::80                      :::*
客户端访问:http://10.0.0.102/install/注意一定要在这里安装完成,否则搭建完反代再安装就晚了。可能会不识别静态内容
Host RS2与Host RS1的配置相同,此处不再复制

Host VS1
挂在HostDB上的NFS共享存储到Host VS1上
# showmount -e 10.0.0.202
Export list for 10.0.0.202:
/nfshare 10.0.0.0/8
# mkdir /htdocs
# mount -t nfs 10.0.0.202:/nfshare /htdocs


使用upstream模块为后端RS主机做反代,并为其配置SorryServer,在后端RS主机宕机的时候,能够给用户一些友好的提示
# vim /etc/nginx/conf.d/default.conf
upstream backend {
server 10.0.0.101 weight=1 max_fails=3 fail_timeout=3;
server 10.0.0.102 weight=1 max_fails=3 fail_timeout=3;
server 10.0.0.111:8080 backup;  <--当所有RS不可用时,backup可以定义一台备用主机
server 10.0.0.112:8080 backup;

}

server {
listen 80;
server_name localhost;

# 当nginx将php代码送至后端RS处理时请求头中的Host值会是backend.
# php代码在RS上处理时,其内部代码会去请求图片/层叠样式表等静态资源以填充页面.
# 而php代码去请求静态资源时使用的是如http://backend/xxxx.gif这样的url,自然是取不到的.
# 所以我们要在nginx向后代理遇到Host为backend时,将其转换为127.0.0.1.

set $my_host $http_host;
if ($http_host = "backend") {
set $my_host "127.0.0.1";
}

location / {
proxy_pass   http://backend; proxy_set_header Host $my_host;
}
}

server {
listen 8080;
server_name localhost;
charset utf-8;

root   /usr/local/nginx/html;
index  index.html index.htm;

# sorry_server仅提供主页面, 访问其它资源也转至主页面.
location ~ .* {
error_page  404  /;
}
}


生成sorry_server的页面,测试语法无误后启动nginx
# echo "服务维护中,请稍后访问." > /usr/share/nginx/html/index.html
# nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
[root@8a028eb8 ~]# nginx
[root@8a028eb8 nginx]# ss -tnl | grep 80
LISTEN     0      128                       *:8080                     *:*
LISTEN     0      128                       *:80                       *:*


修改keepalived配置文件,此处无需像lvs一样定义virtual_server和real_server
调度算法这些东西了,这些工作全由nginx完成
# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
notification_email {
root@localhost  # 邮件给本机root用户
}
notification_email_from kaadmin@twoyang.com
smtp_server 127.0.0.1  # 使用本机作为smtp服务器
smtp_connect_timeout 30
router_id 8a028eb8  # 标识主机,可以使用主机名.
vrrp_mcast_group4 224.0.71.18  # 多播地址,用于发送心跳信号.尽量让集群内的主机处于同一个独立的多播地址.
}

# nginx进程监控脚本.如果进程不在,降低自身权重,使从节点主机优先级高于自身,将VRRP漂移至从节点主机.
vrrp_script chk_nginx {
script "killall -0 nginx"
interval 2
weight -8
}

vrrp_instance VI_1 {
state MASTER  # vrrp实例VI_1中HostA作为主
interface eth0
virtual_router_id 71 # 0-255范围内的数字,用于区分vrrp实例,所以两个实例不能一致.
priority 100    # MASTER的优先级要高一些
advert_int 1
authentication {
auth_type PASS
auth_pass uWjblY61  # 简单字符认证, 8位任意字符串.
}
virtual_ipaddress {
10.0.0.0.111/8 brd 10.0.0.111 dev eno16777736 label eno16777736:0  # VIP1
}

# 在此处调用nginx进程监控脚本
track_script {
chk_nginx
}

# 关闭争用. 争用是指当高优先级节点上线会立即争夺成为MASTER
# 而不管其它节点是否正在给用户提供服务.
#nopreempt

# 开启争用时,会延迟一段时间才开始.
#preempt_delay 300
}

vrrp_instance VI_2 {
state BACKUP    # vrrp实例VI_2中HostA作为备
interface eth0
virtual_router_id 171
priority 95     # BACKUP的优先级要低一些
advert_int 1
authentication {
auth_type PASS
auth_pass uWjblY62
}
virtual_ipaddress {
10.0.0.112/8 brd 10.0.0.112 dev eno16777736 label eno16777736:1  # VIP2
}

# 在此处调用nginx进程监控脚本
track_script {
chk_nginx
}
}
启动keepalived服务,并检查ip地址和日志,可以看到HostVS1 VI_2实例的BACKUP,优先级较低,但是由于作为VI_2实例MASTER的HostVS2主机还没有启动keepalived服务,所以HostVS1获取到了VI_2实例的VIP 10.0.0.112

Host VS2
挂载HostDB上的NFS共享存储目录

# showmount -e 10.0.0.202
Export list for 10.0.0.202:
/nfshare 10.0.0.0/8
# mkdir /htdocs
# mount -t nfs 10.0.0.202:/nfshare /htdocs


使用upstream模块为后端RS主机做反代,并为其配置SorryServer,在后端RS主机宕机的时候,能够给用户一些友好的提示
# vim /etc/nginx/conf.d/default.conf
upstream backend {
server 10.0.0.101 weight=1 max_fails=3 fail_timeout=3;
server 10.0.0.102 weight=1 max_fails=3 fail_timeout=3;
server 10.0.0.111:8080 backup;
server 10.0.0.112:8080 backup;
}

server {
listen 80;
server_name localhost;

# 当nginx将php代码送至后端RS处理时请求头中的Host值会是backend.
# php代码在RS上处理时,其内部代码会去请求图片/层叠样式表等静态资源以填充页面.
# 而php代码去请求静态资源时使用的是如http://backend/xxxx.gif这样的url,自然是取不到的.
# 所以我们要在nginx向后代理遇到Host为backend时,将其转换为127.0.0.1.

set $my_host $http_host;
if ($http_host = "backend") {
set $my_host "127.0.0.1";
}

location / {
proxy_pass   http://backend; proxy_set_header Host $my_host;
}
}

server {
listen 8080;
server_name localhost;
charset utf-8;

root   /usr/local/nginx/html;
index  index.html index.htm;

# sorry_server仅提供主页面, 访问其它资源也转至主页面.
location ~ .* {
error_page  404  /;
}
}


生成sorry_server的页面,测试语法无误后启动nginx
# echo "服务维护中,请稍后访问." > /usr/share/nginx/html/index.html
# nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
[root@8a028eb8 ~]# nginx
[root@8a028eb8 nginx]# ss -tnl | grep 80
LISTEN     0      128                       *:8080                     *:*
LISTEN     0      128                       *:80


修改Host VS2的keepalived配置文件,配置文件无需大改,只需要修改二者的主从关系和优先级即可
# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
notification_email {
root@localhost  # 邮件给本机root用户
}
notification_email_from kaadmin@twoyang.com
smtp_server 127.0.0.1  # 使用本机作为smtp服务器
smtp_connect_timeout 30
router_id 8a028eb8  # 标识主机,可以使用主机名.
vrrp_mcast_group4 224.0.71.18  # 多播地址,用于发送心跳信号.尽量让集群内的主机处于同一个独立的多播地址.
}

# nginx进程监控脚本.如果进程不在,降低自身权重,使从节点主机优先级高于自身,将VRRP漂移至从节点主机.
vrrp_script chk_nginx {
script "killall -0 nginx"
interval 2
weight -8
}

vrrp_instance VI_1 {
state BACKUP  # vrrp实例VI_1中HostA作为主
interface eno16777736
virtual_router_id 71 # 0-255范围内的数字,用于区分vrrp实例,所以两个实例不能一致.
priority 98    # MASTER的优先级要低一些
advert_int 1
authentication {
auth_type PASS
auth_pass uWjblY61  # 简单字符认证, 8位任意字符串.
}
virtual_ipaddress {
10.0.0.0.111/8 brd 10.0.0.111 dev eno16777736 label eno16777736:0  # VIP1
}

# 在此处调用nginx进程监控脚本
track_script {
chk_nginx
}

# 关闭争用. 争用是指当高优先级节点上线会立即争夺成为MASTER
# 而不管其它节点是否正在给用户提供服务.
#nopreempt

# 开启争用时,会延迟一段时间才开始.
#preempt_delay 300
}

vrrp_instance VI_2 {
state BACKUP    # vrrp实例VI_2中HostA作为备
interface eno16777736
virtual_router_id 171
priority 100     # BACKUP的优先级要高一些
advert_int 1
authentication {
auth_type PASS
auth_pass uWjblY62
}
virtual_ipaddress {
10.0.0.112/8 brd 10.0.0.112 dev eno16777736 label eno16777736:1  # VIP2
}

# 在此处调用nginx进程监控脚本
track_script {
chk_nginx
}
}
启动keepalived服务,并检查IP地址和日志,可以看到HostVS2作为VI_2实例的MASTER,优先级较高,在争用模式下,HostVS2立刻获取到了VI_2的VIP 10.0.0.112

测试:分别访问http://10.0.0.111/和10.0.0.112/
轮流关闭Host VS1和Host VS2的keepalived服务和nginx服务,都不会影响用户访问

由于nginx对后端RS主机的健康状态检测模块health_check已经被商业化,我们只能考虑使用由淘宝技术团队开发的tengine,所以我们要想实现,某一台RS宕机之后,仍然能继续工作,以及RS全部宕机还能够提供Sorry-server页面就需要使用tengine,我们下一篇博客细细讲解
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