项目场景：
在Linux系统下，源码包解压安装了Keepalived服务,安装完后使用systemctl start keepalived.service命令启动服务未能成功启动服务。
问题描述：
运行了systemctl start keepalived.service命令启动服务；
然后使用ps -aux | grep keepalived 查看服务启动情况；
输出结果为：
root 21068 0.0 0.0 112812 976 pts/0 S+ 17:04 0:00 grep --color=auto keepalived
这是服务没有运行起来呀。
原因分析：
运行systemctl status keepalived.service命令查看服务状态；
输出结果为：
● keepalived.service - LVS and VRRP High Availability Monitor
Loaded: loaded (/usr/lib/systemd/system/keepalived.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Tue 2021-03-23 16:36:49 CST; 6s ago
Process: 20699 ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS (code=exited, status=7)
Mar 23 16:36:49 tinghs systemd[1]: Starting LVS and VRRP High Availability Monitor...
Mar 23 16:36:49 tinghs Keepalived[20699]: Starting Keepalived v2.2.2 (03/05,2021)
Mar 23 16:36:49 tinghs systemd[1]: keepalived.service: control process exited, code=exited status=7
Mar 23 16:36:49 tinghs systemd[1]: Failed to start LVS and VRRP High Availability Monitor.
Mar 23 16:36:49 tinghs systemd[1]: Unit keepalived.service entered failed state.
Mar 23 16:36:49 tinghs systemd[1]: keepalived.service failed.
Mar 23 16:36:49 tinghs systemd[1]: Failed to start LVS and VRRP High Availability Monitor.
这个是它报红的一行。
使用journalctl -xe 命令查看详细信息；
输出结果为：
Mar 23 16:36:49 tinghs Keepalived[20699]: Starting Keepalived v2.2.2 (03/05,2021)
Mar 23 16:36:49 tinghs Keepalived[20699]: Running on Linux 3.10.0-1127.el7.x86_64 #1 SMP Tue Mar 31 23:36:51 UTC 2020 (built for Linux 3.10.0)
Mar 23 16:36:49 tinghs Keepalived[20699]: Command line: '/usr/local/keepalived/sbin/keepalived' '-D'
Mar 23 16:36:49 tinghs Keepalived[20699]: CPU usage (self/children) user: 0.001035/0.000000 system: 0.014492/0.000000
Mar 23 16:36:49 tinghs Keepalived[20699]: Stopped Keepalived v2.2.2 (03/05,2021)
Mar 23 16:36:49 tinghs systemd[1]: keepalived.service: control process exited, code=exited status=7
Mar 23 16:36:49 tinghs systemd[1]: Failed to start LVS and VRRP High Availability Monitor.
-- Subject: Unit keepalived.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit keepalived.service has failed.
--
-- The result is failed.
Mar 23 16:36:49 tinghs systemd[1]: Unit keepalived.service entered failed state.
Mar 23 16:36:49 tinghs systemd[1]: keepalived.service failed.
Mar 23 16:36:49 tinghs polkitd[685]: Unregistered Authentication Agent for unix-process:20693:165200446 (system bus name :1.1022, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
Mar 23 16:36:49 tinghs Keepalived[20699]: Command line: ‘/usr/local/keepalived/sbin/keepalived’ ‘-D’
从这一行可以看出，启动服务时没有指定配置文件。
我们去查看一下/usr/lib/systemd/system/keepalived.service 文件，运行 cat /usr/lib/systemd/system/keepalived.service命令；
输出结果为：
[Unit]
Description=LVS and VRRP High Availability Monitor
After=network-online.target syslog.target
Wants=network-online.target
[Service]
Type=forking
PIDFile=/run/keepalived.pid
KillMode=process
EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived
ExecStart=/usr/local/keepalived/sbin/keepalived $KEEPALIVED_OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
[Install]
WantedBy=multi-user.target
EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived
根据这一行去寻找 config , 运行 cat /usr/local/keepalived/etc/sysconfig/keepalived 命令；
输出结果为：
# Options for keepalived. See `keepalived --help' output and keepalived(8) and
# keepalived.conf(5) man pages for a list of all options. Here are the most
# common ones :
#
# --vrrp -P Only run with VRRP subsystem.
# --check -C Only run with Health-checker subsystem.
# --dont-release-vrrp -V Dont remove VRRP VIPs & VROUTEs on daemon stop.
# --dont-release-ipvs -I Dont remove IPVS topology on daemon stop.
# --dump-conf -d Dump the configuration data.
# --log-detail -D Detailed log messages.
# --log-facility -S 0-7 Set local syslog facility (default=LOG_DAEMON)
#
KEEPALIVED_OPTIONS="-D"
KEEPALIVED_OPTIONS="-D"
重点就是上面这一行了；
解决方案：
运行 vi /usr/local/keepalived/etc/sysconfig/keepalived 命令,shift+G 将光标移动至文件末尾，点击 i ，将文件改为：
# Options for keepalived. See `keepalived --help' output and keepalived(8) and
# keepalived.conf(5) man pages for a list of all options. Here are the most
# common ones :
#
# --vrrp -P Only run with VRRP subsystem.
# --check -C Only run with Health-checker subsystem.
# --dont-release-vrrp -V Dont remove VRRP VIPs & VROUTEs on daemon stop.
# --dont-release-ipvs -I Dont remove IPVS topology on daemon stop.
# --dump-conf -d Dump the configuration data.
# --log-detail -D Detailed log messages.
# --log-facility -S 0-7 Set local syslog facility (default=LOG_DAEMON)
#KEEPALIVED_OPTIONS="-D"
# 根据个人安装的目录指定keepalived配置文件
KEEPALIVED_OPTIONS="-f /usr/local/keepalived/etc/keepalived/keepalived.conf -D -S 0"
点击 Esc ，输入:wq ,点击Enter，保存并退出。
再次运行systemctl start keepalived.service命令启动服务，就可以启动成功了。
systemctl 服务相关命令
# 重新加载服务
systemctl daemon-reload
# 启动服务
systemctl start keepalived.service
# 停止服务
systemctl stop keepalived.service
# 重启服务
systemctl restart keepalived.service
# 查看服务状态
systemctl status keepalived.service
# 设置开机自动启动服务
systemctl enable keepalived.service
# 取消开机自动启动服务
systemctl disable keepalived.service
# 查看服务是否开机启动
systemctl is-enabled keepalived.service
# 查看已启动的服务列表
systemctl list-unit-files|grep enabled
# 查看启动失败的服务列表
systemctl --failed