Monitor Tool 2019(1)Monit Installation and Usage

Monitor Tool 2019(1)Monit Installation and Usage

On CentOS 7
> sudo yum install monit
Check version
> monit -V
This is Monit version 5.25.1
Built with ssl, with ipv6, with compression, with pam and with large files
Copyright (C) 2001-2017 Tildeslash Ltd. All Rights Reserved.

Some useful command
Check configuration file
> sudo monit -t
Control file syntax OK

The configuration file will be
/etc/monitrc
/etc/monit.d/

Start the service
> sudo monit
Starting Monit 5.25.1 daemon with http interface at [localhost]:2812

Reload the configuration
> sudo monit reload
Reinitializing monit daemon

Check status
> sudo monit status
Monit 5.25.1 uptime: 1m
System 'rancher-home'
  status                       OK
  monitoring status            Monitored
  monitoring mode              active
  on reboot                    start
  load average                 [0.09] [0.66] [0.49]
  cpu                          3.2%us 1.7%sy 0.7%wa
  memory usage                 1.3 GB [45.6%]
  swap usage                   264 kB [0.0%]
  uptime                       7m
  boot time                    Sat, 12 Oct 2019 17:14:20
  data collected               Sat, 12 Oct 2019 17:21:46

My first simple configuration file is as follow:
> sudo vi /etc/monitrc
set daemon  30              # check services at 30 seconds intervals
set httpd port 2812 and
    use address rancher-home
    allow admin:admin
include /etc/monit.d/*

Visit this page to see some basic monitor informations.
http://rancher-home:2812/

We can configure all the monitor separately in /etc/monit.d/*

Check Disk
> df -lh
Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 1.4G     0  1.4G   0% /dev
tmpfs                    1.4G     0  1.4G   0% /dev/shm
tmpfs                    1.4G  9.3M  1.4G   1% /run
tmpfs                    1.4G     0  1.4G   0% /sys/fs/cgroup
/dev/mapper/centos-root   36G   12G   25G  33% /
/dev/sda1               1014M  232M  783M  23% /boot
tmpfs                    285M     0  285M   0% /run/user/1000

Add the configuration file follow the pattern

check <Type> <ServiceName> [PATH <path>] [ADDRESS <host address>]

Type - system, file, process, fifo, filesystem, directory, host, network, program

> cat /etc/monit.d/filesystem
check filesystem datafs with path /dev/mapper/centos-root
  if space usage > 50% then alert
  group server

Check config
> sudo monit -t
Control file syntax OK

Restart the service
> sudo monit reload
Reinitializing monit daemon

More example:
https://www.cnblogs.com/52fhy/p/6412547.html

Try monitor HAProxy
http://rancher-home:8100/stats
PID file
> ls -l /opt/haproxy/haproxy.pid
-rw-r--r--. 1 root root 12 Oct 13 11:33 /opt/haproxy/haproxy.pid

REG process
> ps -ef | grep haproxy
nobody   23904     1  0 11:33 ?        00:00:00 sbin/haproxy -f conf/haproxy.conf
nobody   23905     1  0 11:33 ?        00:00:00 sbin/haproxy -f conf/haproxy.conf
carl     25127 17104  0 11:38 pts/1    00:00:00 grep --color=auto haproxy

Here is how the haproxy configuration
> cat /etc/monit.d/haproxy
check process haproxy with pidfile /opt/haproxy/haproxy.pid
  start program = "/opt/haproxy/sbin/haproxy -f /opt/haproxy/conf/haproxy.conf" with timeout 20 seconds
  stop program = "/usr/bin/kill haproxy"
  if changed pid then restart

Latest document
https://mmonit.com/monit/documentation/monit.html

Source Installation
https://cloud.tencent.com/developer/article/1114319
Check the latest version from here
https://mmonit.com/monit/dist/

> wget https://mmonit.com/monit/dist/monit-5.26.0.tar.gz
> tar zxvf monit-5.26.0.tar.gz
> cd monit-5.26.0

Some possible Exception
configure: error: libz not found

configure: error: PAM enabled but headers or library not found, install the PAM development support or run configure --without-pam

Couldn't find your SSL header files.
Use --with-ssl-incl-dir option to fix this problem or disable
the SSL support with --without-ssl

Prepare build ENV if needed
> sudo yum groupinstall "Development tools"
> sudo yum install zlib-devel
> sudo yum list *pam*
> sudo yum install pam-devel
> sudo yum install openssl-devel


Configure and Build
> ./configure --prefix=/home/carl/tool/monit-5.26.0
> make
> make install

Prepare the configuration file
> sudo cp monitrc /etc/monitrc
> sudo chown root:root /etc/monitrc
> sudo chmod 0700 /etc/monitrc

> sudo ln -s /home/carl/tool/monit-5.26.0 /opt/monit-5.26.0
> sudo ln -s /opt/monit-5.26.0 /opt/monit

Change the configuration as follow:
set httpd port 2812 and
    use address rancher-worker2
    allow 0.0.0.0/0.0.0.0
    allow admin:admin
  include /etc/monit.d/*

Start the service
> sudo bin/monit


References:
https://www.jianshu.com/p/248d6456e83f
https://linjunzhu.github.io/blog/2015/08/14/ru-he-shi-yong-monitjian-kong-jin-cheng/
https://mmonit.com/monit/documentation/monit.html
https://cloud.tencent.com/developer/article/1114319