tree -l命令参考

一、简介

Keepalived是一个免费开源的，用C编写的类似于layer3, 4 & 7交换机制软件，具备我们平时说的第3层、第4层和第7层交换机的功能。主要提供loadbalancing（负载均衡）和 high-availability（高可用）功能，负载均衡实现需要依赖Linux的虚拟服务内核模块（ipvs），而高可用是通过VRRP协议实现多台机器之间的故障转移服务。

上图是Keepalived的功能体系结构，大致分两层：用户空间（user space）和内核空间（kernel space）。 
内核空间：主要包括IPVS（IP虚拟服务器，用于实现网络服务的负载均衡）和NETLINK（提供高级路由及其他相关的网络功能）两个部份。 
用户空间：

• WatchDog：负载监控checkers和VRRP进程的状况
• VRRP Stack：负载负载均衡器之间的失败切换FailOver，如果只用一个负载均稀器，则VRRP不是必须的。
• Checkers：负责真实服务器的健康检查healthchecking，是keepalived最主要的功能。换言之，可以没有VRRP Stack，但健康检查healthchecking是一定要有的。
• IPVS wrapper：用户发送设定的规则到内核ipvs代码
• Netlink Reflector：用来设定vrrp的vip地址等。

Keepalived的所有功能是配置keepalived.conf文件来实现的。

二、安装与配置

从官网下载keepalived，本文以版本1.2.24为例。

2.1 安装

[root@keepalived-nginx1 ~]# wget http://www.keepalived.org/software/keepalived-1.2.24.tar.gz
[root@keepalived-nginx1 ~]# tar -xzvf keepalived-1.2.24.tar.gz
[root@keepalived-nginx1 ~]# cd keepalived-1.2.24

[root@keepalived-nginx1 keepalived-1.2.24]# ./configure --prefix=/usr/local/keepalived
[root@keepalived-nginx1 keepalived-1.2.24]# make && make install

2.2 配置

安装完成后，进入安装目录的etc目录下，将keepalived相应的配置文件拷贝到系统相应的目录当中。keepalived启动时会从/etc/keepalived目录下查找keepalived.conf配置文件，如果没有找到则使用默认的配置。/etc/keepalived目录安装时默认是没有安装的，需要手动创建。配置文件目录结构如下所示：

[root@keepalived-nginx1 ~]# tree -l /usr/local/keepalived/etc/
/usr/local/keepalived/etc/
├── keepalived
│   ├── keepalived.conf
│   └── samples
│       ├── client.pem
│       ├── dh1024.pem
│       ├── keepalived.conf.fwmark
│       ├── keepalived.conf.HTTP_GET.port
│       ├── keepalived.conf.inhibit
│       ├── keepalived.conf.IPv6
│       ├── keepalived.conf.misc_check
│       ├── keepalived.conf.misc_check_arg
│       ├── keepalived.conf.quorum
│       ├── keepalived.conf.sample
│       ├── keepalived.conf.SMTP_CHECK
│       ├── keepalived.conf.SSL_GET
│       ├── keepalived.conf.status_code
│       ├── keepalived.conf.track_interface
│       ├── keepalived.conf.virtualhost
│       ├── keepalived.conf.virtual_server_group
│       ├── keepalived.conf.vrrp
│       ├── keepalived.conf.vrrp.localcheck
│       ├── keepalived.conf.vrrp.lvs_syncd
│       ├── keepalived.conf.vrrp.routes
│       ├── keepalived.conf.vrrp.rules
│       ├── keepalived.conf.vrrp.scripts
│       ├── keepalived.conf.vrrp.static_ipaddress
│       ├── keepalived.conf.vrrp.sync
│       ├── root.pem
│       └── sample.misccheck.smbcheck.sh
├── rc.d
│   └── init.d
│       └── keepalived
└── sysconfig
    └── keepalived

分别对应系统目录（忽略samples目录）：

/etc/keepalived/keepalived.conf
/etc/rc.d/init.d/keepalived
/etc/sysconfig/keepalived

将配置文件拷贝到系统对应的目录下：

[root@keepalived-nginx1 ~]# mkdir /etc/keepalived
[root@keepalived-nginx1 ~]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf
[root@keepalived-nginx1 ~]# cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/keepalived
[root@keepalived-nginx1 ~]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/keepalived

[root@keepalived-nginx1 ~]# cd /etc/init.d/
[root@keepalived-nginx1 init.d]# chmod +x keepalived
[root@keepalived-nginx1 init.d]# service keepalived start
Starting keepalived: /bin/bash: keepalived: command not found
                                                           [FAILED]
[root@keepalived-nginx1 init.d]# ln -s /usr/local/keepalived/sbin/keepalived /usr/bin/
[root@keepalived-nginx1 init.d]# service keepalived start
Starting keepalived:                                       [  OK  ]

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