Using Monit to monitor processes and system status in Linux

But the reality is brutal, many software itself stability to be promoted, the machine hardware resources upgrade will touch the cost, therefore in the cluster environment, has the redundancy, makes the implementation simple service restart becomes the most realistic choice.

This is not a difficult thing in itself, there are many ways to implement it, such as adding action or commands to Zabbix or nagios alarms, or writing scripts to execute on a scheduled task.

But what this article is going to introduce is a tool dedicated to doing such things: Monit.
Its biggest feature is that the configuration file is easy to read, while supporting process and system State monitoring, and flexible to provide a variety of detection methods, cycles, and alarm and response (restart Service, execute command, etc.)

System environment:
Os:centos 6.4 x86_64 Minimal

Specific configuration:
1. Install Epel Warehouse

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# yum Install http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

2. Install Monit Package

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# yum Install Monit

3. Configuration Monit general parameters, including the opening of the HTTP statistics interface, mail alarm, etc.

The code is as follows

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# vim/etc/monit.conf ############################################################################### # # Monit Control file ############################################################################### ## # # Comments begin with a ' # ' and extend through the ' end of the '. Keywords # # are case insensitive. All path ' s must is fully qualified, starting with '/'. ## # # Below You'll find examples of some frequently used statements. For # # Information about the control file and a complete list of statements and # # options, please have a look in the Monit manual. ## ## ############################################################################### # # Global Section ############################################################################### ## # # Start Monit in the background (run as a daemon): # Set Daemon # Check services at 2-minute intervals With start delay # Optional:delay the ' I Check by 4-minutes ' (by # # Default Monit check immediately after monit start) # # # # Set syslog logging with the ' daemon ' facility. If The facility option is # # omitted, Monit'll use ' user ' facility by default. If you are want to log to # a standalone log file instead, specify the full path to the log file # # set logfile syslog facility Log_daemon # # ### Set The location of the Monit ID file which stores the unique ID for the ### Monit instance. The ID is generated and stored on the start Monit. By ### default the file is placed in $HOME/.monit.id. # Set Idfile/var/run/monit/.monit.id # www.111cn.net ### Set The location of the Monit state file which saves monitoring ### on each cycle. By default the ' file is ' placed in $HOME/.monit.state. If ### the state file was stored on a persistent filesystem, monit'll recover ### the monitoring state across reboots. If It is on temporary filesystem, the ### state is lost on reboot which May is convenient in some situations. # Set Statefile/var/run/monit/.monit.state # # # Set The list of mail servers for alert delivery. Multiple servers May # # specified using a comma separator. By default Monit uses port 25-it is # # possible to override this with the PORT option. # Set mailserver localhost # set MailServer Mail.bar.baz, # Primary MailServer # Backup.bar.baz Port 10025, # Backup mailserver on port 10025 # localhost # fallback relay # # # # By default Monit would drop alert events if no mail servers are available. # # IF You are want to keep the alerts for later delivery retry, can use the # # EventQueue statement. The base directory where undelivered alerts would be # # stored is specified by the BASEDIR option. You can limit the maximal queue # # Size using the slots option (if omitted, the queue is limited by # # available in the ' Back ' end filesystem). # Set EventQueue Basedir/var/run/monit # Set the base directory where events would be stored # slots # Optionally limit the queue size # # # # Send Status and events to M/monit informations about M/monit # # http://mmonit.com/). # # set Mmonit http://monit:monit@192.168.1.10:8080/collector # # # # Monit By default uses the following alert mail format: ## # #--8<-- # # from:monit@ $HOST # Sender # # Subject:monit Alert-event: $EVENT Service: $SERVICE # Subject ## # # Event: $EVENT Service: $SERVICE # ##                                           # # # Date: $DATE # # # Action: $ACTION # # # Host: $HOST # Body # # Description: $DESCRIPTION # ##                                           # # # Your Faithful Employee, # # # Monit # # #--8<-- ## # # can override this message format or parts of it, such as subject # # or sender using the Mail-format statement. Macros such as $DATE, etc. # # are expanded at runtime. For example, to override the sender, use: # Set Mail-format { From:monit@heylinux.com Subject: [$SERVICE] $EVENT Message [$SERVICE] $EVENT Date: $DATE Action: $ACTION Host:heylinux.com Description: $DESCRIPTION Your Faithful Employee, Monit} # # # # You can set alert recipients whom'll receive alerts If/when a # # Service defined in this file has errors. Alerts May is restricted on # # Events by using a filter as in the second example below. # Set Alert guosuiyu@foxmail.com # Set Alert Sysadm@foo.bar # Receive all Alerts # Set Alert Manager@foo.bar only on {timeout} # receive just service- # # Timeout Alert # # # # Monit has an embedded Web server which can is used to view status of # # Services monitored and manage services from a Web interface. The # # Monit Wiki If you are want to enable SSL for the Web server. # Set httpd port 2812 and Use address localhost # accept connection from localhost Allow localhost # allow localhost to connect to the server and # Allow Admin:monit # require user ' admin ' with password ' monit ' # Allow @monit # allow users of group ' Monit ' to connect (rw) # Allow @users readonly # allow users of group ' users ' to connect readonly # # ############################################################################### # # Services ############################################################################### ## # # Check General system resources such as load average, CPU and memory # # Usage. Each test specifies a resource, conditions and the action # # performed should a test fail. # # Check System Myhost.mydomain.tld # if LOADAVG (1min) > 4 then alert # if LOADAVG (5min) > 2 then alert # If memory usage > 75% then alert # If CPU usage (user) > 70% then alert # If CPU usage (System) > 30% then alert # If CPU usage (wait) > 20% then alert # # # # Check A file for existence, checksum, permissions, UID and GID. In addition # # to alert recipients in the global section, customized alert can is sent to # # Additional recipients by specifying a, local alert handler. The service may # # is grouped using the GROUP option. More than one group can is specified by # # repeating the ' group name ' statement. # # Check file Apache_bin with PATH/USR/LOCAL/APACHE/BIN/HTTPD # if failed checksum and # expect the sum 8f7f419955cefa0b33a2ba316cba3659 then Unmonitor # if failed permission 755 then Unmonitor # if failed uid root then Unmonitor # if failed GID root then Unmonitor # alert Security@foo.bar on { # checksum, permission, UID, GID, unmonitor #} with the Mail-format {subject:alarm!} # Group Server # # # # Check That ' a process is running ', in the case Apache, and that it respond # # to HTTP and HTTPS requests. Check its resource usage such as CPU and memory, # # and number of children. If the process is not running, Monit'll restart # # It by default. In case the service is restarted very often and the # # problem remains, it is possible to disable monitoring using the TIMEOUT # # statement. This service depends on another service (Apache_bin) which # # is defined above. # # check process Apache with Pidfile/usr/local/apache/logs/httpd.pid # Start program = '/etc/init.d/httpd start ' with timeout seconds # Stop program = '/etc/init.d/httpd Stop ' # If CPU > 60% for 2 cycles then alert # If CPU > 80% for 5 cycles then restart # if Totalmem > 200.0 MB for 5 cycles then restart # if children > then restart # if LOADAVG (5min) greater than for 8 cycles then stop # if failed host www.tildeslash.com Port protocol http # and request '/somefile.html ' # then restart # if failed port 443 type TCPSSL protocol HTTP # with timeout seconds # then restart # if 3 restarts within 5 cycles then timeout # depends on Apache_bin # Group Server # # # # Check filesystem permissions, UID, GID, Space and inode usage. Other services, # # such as databases, may depend on this resource and a automatically graceful # # cascaded to them before the filesystem would become full and data # # Lost. # # check filesystem Datafs with PATH/DEV/SDB1 # Start program = '/bin/mount/data ' # Stop program = '/bin/umount/data ' # if failed permission 660 then Unmonitor # if failed uid root then Unmonitor # if failed GID disk then Unmonitor # If spaces usage > 80% for 5 times within cycles then alert # If space usage > 99% then stop # if Inode usage > 30000 then alert # if Inode usage > 99% then stop # Group Server # # # # Check A file ' s timestamp. In the example, we test if a file is older # # than minutes and assume something is wrong if it not updated. Also, # # If the file size exceed a given limit, execute a script # # Check file database with Path/data/mydatabase.db # if failed permission then alert # if failed UID data then alert # if failed GID data then alert # if timestamp > minutes then alert # if size > MB then exec "/my/cleanup/script" as UID DBA and GID DBA # # # # Check Directory permission, UID and GID. An event is triggered if the # # Directory does not belong to the ' user with uid 0 and GID 0. In addition, # # The permissions have to match the octal description of 755 (in the chmod (1)). # # Check Directory bin with Path/bin # if failed permission 755 then Unmonitor # if failed UID 0 then Unmonitor # if failed GID 0 then Unmonitor # # # # Check A remote host availability by issuing a ping test and check the # # Content of a response from a Web server. Up to three pings are sent and # # Connection to a port and the application level network the check is performed. # # Check host MyServer with address 192.168.1.1 # if failed ICMP type echo count 3 with timeout 3 seconds then alert # if failed port 3306 protocol MySQL with timeout seconds then alert # if failed URL http://user:password@www.foo.bar:8080/?querystring # and content = = ' action= ' J_security_check ' # then alert # # ############################################################################### # # Includes ############################################################################### ## # # It is possible to include additional configuration parts from other files or # # directories. # # include/etc/monit.d/* # # # Include All Files from/etc/monit.d/ include/etc/monit.d/*

4. For example configuration for nginx,php-fpm,mysql and root partition dosage monitoring
In the configuration file in step 3, you can see that there are many configuration examples in the annotated code that are sufficient for reference.
Here, to share with you the relevant monitoring items I created in my VPS:

The code is as follows

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# Vim/etc/monit.d/nginx Check process Nginx with Pidfile/webserver/nginx/run/nginx.pid Start program = "/webserver/init.d/nginx start" with timeout seconds Stop program = "/webserver/init.d/nginx Stop" If failed host heylinux.com Port protocol http With timeout seconds Then restart If 3 restarts within 5 cycles then timeout Group webserver # VIM/ETC/MONIT.D/PHP-FPM Check process php-fpm with Pidfile/webserver/php/logs/php-fpm.pid Start program = "/webserver/init.d/php-fpm start" with timeout seconds Stop program = "/WEBSERVER/INIT.D/PHP-FPM Stop" If CPU > 80% for 5 cycles then restart If Loadavg (5min) greater than 4 for 5 cycles then restart If 3 restarts within 5 cycles then timeout Group webserver # Vim/etc/monit.d/mysql Check process MySQL with Pidfile/webserver/mysql/run/mysqld.pid Start program = "/webserver/init.d/mysqld start" with timeout seconds Stop program = "/webserver/init.d/mysqld Stop" If failed port 3306 protocol MySQL With timeout seconds Then restart If 3 restarts within 5 cycles then timeout Group webserver # Vim/etc/monit.d/rootfs Check filesystem Rootfs with Path/dev/xvde If spaces usage > 80% for 5 times within cycles then alert Group OS

5. Start Monit

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# Mkdir/var/run/monit #/etc/init.d/monit Start

6. Simulate Nginx process failure, test monit response behavior and alarm
Stop Nginx Process

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#/webserver/init.d/nginx Stop #/webserver/init.d/nginx Status Nginx is stopped

Watch log output

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# Tailf/var/log/monit [CST APR 01:11:55] Error:skipping/var/run/monit/.monit.id-unknown data format [CST Apr 01:11:55] error:aborting event/var/run/monit/.monit.state-invalid size 5 [CST APR 01:41:56] Error: ' Nginx ' process is not running [CST Apr 01:41:56] Info: ' Nginx ' trying to restart [CST Apr 01:41:56] Info: ' nginx ' Start:/webserver/init.d/nginx

Check to see if Nginx is started by monit

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#/webserver/init.d/nginx Status Nginx (PID 22419 22417) is running ...

To view the messages received, a total of two

Message that prompts for a service exception

Messages that prompt service recovery

View the status of all Monit monitoring items

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# Monit Status The Monit daemon 5.1.1 uptime:1h 8m FileSystem ' Rootfs ' Status accessible monitoring status monitored Permission 660 UID 0 GID 6 FileSystem Flags 0x1000 Block size 4096 B Blocks Total 2580302 [10079.3 MB] Blocks free for non superuser 1800023 [7031.3 MB] [69.8%] Blocks free Total 1931088 [7543.3 MB] [74.8%] Inodes Total 655360 Inodes free 607619 [92.7%] Data collected Sat APR 12 02:17:58 2014 Process ' PHP-FPM ' Status Running monitoring status monitored PID 13768 Parent PID 1 Uptime 6h 14m Children 5 Memory kilobytes 3124 Memory Kilobytes Total 220032 Memory percent 0.5% Memory percent Total 36.3% CPU percent 0% CPU percent Total 5.8% Data collected Sat APR 12 02:17:58 2014 Process ' Nginx ' Status Www.111cn.net Running monitoring status monitored PID 22417 Parent PID 1 Uptime 36m Children 1 Memory Kilobytes 1244 Memory Kilobytes Total 29256 Memory percent 0.2% Memory percent Total 4.8% CPU percent 0% CPU percent Total 0% Port response time 0.144s to heylinux.com:80 [HTTP via TCP] Data collected Sat APR 12 02:17:58 2014 Process ' MySQL ' Status Running monitoring status monitored PID 21502 Parent PID 21026 Uptime 1h 13m Children 0 Memory Kilobytes 44988 Memory Kilobytes Total 44988 Memory percent 7.4% Memory percent Total 7.4% CPU percent 0.2% CPU percent Total 0.2% Port response time 0.001s to localhost:3306 [MYSQL via TCP] Data collected Sat APR 12 02:17:58 2014 System ' Ec2-tokyo.localdomain ' Status Running monitoring status monitored Load average [0.12] [0.08] [0.03] CPU 5.9%us 0.5%sy 0.4%wa Memory usage 314260 KB [51.9%] Data collected Sat APR 12 02:17:58 2014