Munin

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Munin是一套Perl撰写的监控软件。

简介

主要的两个元件,由服务器去节点拉资料:

  • munin-cron(可以在/etc/cron.d/munin里面看到)
  • munin-node

网站的部分则是透过这两个元件提供FastCGI界面:

  • munin-cgi-graph
  • munin-cgi-html

安装

Munin目前已经算成熟,更新幅度不会太大,加上Ubuntu内的版本都还算够新[1],可以直接安装Ubuntu内的版本,节点端只需要安装munin-node:

sudo apt install -y munin-node; sudo apt clean

服务器则是安装munin:

sudo apt install -y munin; sudo apt clean

基本设定

节点端

节点端需要把服务器的IP位置加入allow列表(要注意这边的设计是吃Regular Expression),另外防火墙的设定只要把4949/tcp打开即可(预设值,在/etc/munin/munin-node.conf内可以修改)。

服务器端

服务器端的设定,先将Munin设定为CGI模式(事实上会是FastCGI模式),这需要增加/etc/munin/munin-conf.d/cgi.conf这个档案:

graph_strategy cgi
html_strategy cgi
cgiurl_graph /munin-cgi/munin-cgi-graph

接着是修正Ubuntu下的档案权限[2]

sudo chown munin:adm /var/log/munin/munin-cgi-graph.log /var/log/munin/munin-cgi-html.log

另外针对/var/lib/munin/cgi-tmp这个目录,我们希望下面建立出来的档案与目录都是www-data(group):

sudo chmod 2775 /var/lib/munin/cgi-tmp
sudo chown -R munin:www-data /var/lib/munin/cgi-tmp

然后是systemd的设定档,包含了/lib/systemd/system/munin-cgi-graph.service

#
[Unit]
Description=Munin CGI Graph FastCGI daemon
After=remote-fs.target

[Service]
ExecStart=/usr/bin/spawn-fcgi -s /var/run/munin/fastcgi-graph.sock -P /var/run/munin/fastcgi-graph.pid -U www-data -u munin -g munin /usr/lib/munin/cgi/munin-cgi-graph
PIDFile=/var/run/munin/fastcgi-graph.pid
Restart=always
RestartSec=1
Type=simple

[Install]
WantedBy=multi-user.target

以及/lib/systemd/system/munin-cgi-html.service

#
[Unit]
Description=Munin CGI HTML FastCGI daemon
After=remote-fs.target

[Service]
ExecStart=/usr/bin/spawn-fcgi -s /var/run/munin/fastcgi-html.sock -P /var/run/munin/fastcgi-html.pid -U www-data -u munin -g munin /usr/lib/munin/cgi/munin-cgi-html
PIDFile=/var/run/munin/fastcgi-html.pid
Restart=always
RestartSec=1
Type=simple

[Install]
WantedBy=multi-user.target

重读systemd设定,并且设成开机执行,然后跑起来:

sudo systemctl daemon-reload; sudo systemctl enable munin-cgi-graph.service; sudo systemctl enable munin-cgi-html.service; sudo service munin-cgi-graph start; sudo service munin-cgi-html start

最后是nginx的设定[2]

location ^~ /munin-cgi/munin-cgi-graph/ {
    fastcgi_split_path_info ^(/munin-cgi/munin-cgi-graph)(.*);
    fastcgi_param PATH_INFO $fastcgi_path_info;
    fastcgi_pass unix:/var/run/munin/fastcgi-graph.sock;
    include fastcgi_params;
}

location /munin/static/ {
    alias /etc/munin/static/;
}

location /munin/ {
    fastcgi_split_path_info ^(/munin)(.*);
    fastcgi_param PATH_INFO $fastcgi_path_info;
    fastcgi_pass unix:/var/run/munin/fastcgi-html.sock;
    include fastcgi_params;
}

让nginx重读设定档后应该就可以在https://www.example.com/munin/看到内容:

sudo pkill -1 nginx

常用操作

新增主机

主机的资讯可以塞到/etc/munin/munin-conf.d/host-www.example.com.conf下,可以参考munin.conf[3]里的设定说明:

[www.example.com]
    address 1.2.3.4
    load.load.warning 1
    load.load.critical 2

过五分钟后(让munin-cron跑)就会出现在网页上了。其中load.load的部分是Munin的Plugin,可以针对不同的机器有不同的设定。

新增通知

这边可以设定当有发生warning与critical等级的事件时发信通知给logs@example.com:

#
contact.general.always_send warning critical
contact.general.command mail -s "Munin notification - ${var:host}" logs@example.com

要注意这边用到的mail需要安装bsd-mailx才有,系统一般不会安装。

除错

可以用munin-run看设定输出:

sudo munin-run plugin_name config

然后看执行时的输出结果:

sudo munin-run plugin_name

参考资料

外部链接