详解centos7中配置keepalived日志为别的路径

keepalived 安装：

cd <keepalived_sourcecode_path>
./configure --prefix=/usr/local/keepalived
 
make && make install
 
mkdir /etc/keepalived
mkdir /etc/keepalived/scripts
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /root/keepalived-2.0.6/keepalived/etc/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/sbin/keepalived /sbin/keepalived
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
chmod +x /etc/init.d/keepalived

由于在默认状态下keepalived的日志会写入到/var/log/message中，我们需要将此剥离出来。

在centos 6下可以：

（1）首先修改/etc/sysconfig/keepalived文件，注释掉如下，添加如下： 

#KEEPALIVED_OPTIONS="-D"
KEEPALIVED_OPTIONS="-D -d -S 0" 

（2）其次修改 /etc/rsyslog.conf 文件，添加如下：

local0.* /var/log/keepalived.log

在centos 7 下，还需要修改/lib/systemd/system/keepalived.service 文件：

centos 7使用。因为centos 7使用systemctl，通过systemctl调用service，所以需要修改/lib/systemd/system/keepalived.service文件。

将里面的：

EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived
ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS

修改成：

EnvironmentFile=/etc/sysconfig/keepalived
ExecStart=/sbin/keepalived $KEEPALIVED_OPTIONS

然后重新加载service：

systemctl daemon-reload

整体的思路就是，

1. 通过systemctl start keepalived去启动；

2. 启动keepalived的时候，会去读service的配置文件：/lib/systemd/system/keepalived.service；

3. 在service的配置文件时：

3.1 启动文件路径ExecStart=/sbin/keepalived $KEEPALIVED_OPTIONS，即启动方式是带环境变量文件中参数来启动；

3.2 读取环境变量参数EnvironmentFile=/etc/sysconfig/keepalived。

4. $KEEPALIVED_OPTIONS参数是在/etc/sysconfig/keepalived的配置；我们配置的是KEEPALIVED_OPTIONS="-D -d -S 0"；而-S是syslog的facility，0表示放在local0，在/etc/rsyslog.conf 中配置local0.* /var/log/keepalived.log

5. 所以，写日志就去/var/log/keepalived.log了。