1 

     2 =======

     3  monit

     4 =======

     5 .. contents::

     6    :local:

     7 

     8 Official docs

     9 =============

    10 

    11 https://mmonit.com/monit/documentation/monit.html

    12   Main docs.

    13 https://mmonit.com/wiki/Monit/ConfigurationExamples

    14   Real-world configuration examples.

    15 https://mmonit.com/wiki/Monit/FAQ

    16   FAQ

    17 

    18 Debugging monit

    19 ===============

    20 

    21 Run standalone::

    22 

    23   monit -c /path/to/monitrc

    24 

    25 Check syntax::

    26 

    27   monit -t

    28   monit -t -c /path/to/monitrc

    29 

    30 Override log file location in config::

    31 

    32   set log /var/log/monit.log

    33 

    34 or with CLI option::

    35 

    36   monit -l /var/log/monit.log

    37 

    38 Do not go into background::

    39 

    40   monit -I

    41 

    42 Make verbose output::

    43 

    44   monit -v

    45   monit -vv

    46 

    47 Full length commant may look like::

    48 

    49   sudo monit -v status

    50   sudo monit -Iv validate

    51   sudo monit -Ivv -c /path/to/monitrc

    52 

    53 To debug start/stop scripts write wrapper that redirects STDIO to file::

    54 

    55   #/bin/sh

    56   exec 1>my.log

    57   exec 2>my.log

    58   echo "$@"

    59   exec "$@"

    60 Limiting server to ``localhost``::

    61 

    62   set httpd port 2812

    63     use address localhost

    64     allow localhost

    65     allow admin:monit

    66 

    67 Monit modes

    68 ===========

    69 

    70 * In ``active`` mode (the default), Monit will pro-actively monitor a service and in case of

    71 problems raise alerts and/or restart the service.

    72 * In ``passive`` mode, Monit will passively monitor a service and will raise alerts, but will not

    73 try to fix a problem by executing start, stop or restart.

    74 * In ``manual`` mode, Monit will enter active mode only if a service was started via Monit.

    75 

    76 Example::

    77 

    78   check process App with pidfile /var/run/app.pid

    79     start program = "/usr/bin/app start"

    80     stop program = "/usr/bin/app stop"

    81     mode passive

    82 

    83 Alerting

    84 ========

    85 ::

    86 

    87   check process memcached with match memcached

    88     start program = "/usr/bin/systemctl start memcached"

    89     stop program = "/usr/bin/systemctl stop memcached"

    90     if failed host 127.0.0.1 port 11211 protocol MEMCACHE then restart

    91     if cpu > 70% for 2 cycles then alert

    92     if cpu > 98% for 5 cycles then restart

    93     if 2 restarts within 3 cycles then timeout

    94 

    95   check process myapp with pidfile /run/myapp.pid

    96     if does not exist then alert

    97 

    98   check filesystem Ubuntu with path /dev/sda1

    99     if space usage > 90% then alert

   100   check filesystem Home with path /dev/sda3

   101     if space usage > 90% then alert

   102 

   103   check host app_name with address 127.0.0.1

   104     start "/sbin/start app_name"

   105     stop "/sbin/stop app_name"

   106     if failed port 80 protocol HTTP

   107       request /ok

   108       with timeout 5 seconds

   109       then restart

   110 

   111 Running monit by systemd

   112 ========================

   113 ::

   114 

   115   [Unit]

   116   Description=Pro-active monitoring utility for unix systems

   117   After=network.target

   118   Documentation=man:monit(1) https://mmonit.com/wiki/Monit/HowTo

   119 

   120   [Service]

   121   Type=simple

   122   KillMode=process

   123   ExecStart=/usr/local/bin/monit -I

   124   ExecStop=/usr/local/bin/monit quit

   125   ExecReload=/usr/local/bin/monit reload

   126   Restart = on-abnormal

   127   StandardOutput=null

   128 

   129   [Install]

   130   WantedBy=multi-user.target

   131 

   132 https://mmonit.com/wiki/Monit/Systemd

   133   Official docs.

   134 

   135 Monitor systemd process

   136 =======================

   137 

   138 With pid-file::

   139 

   140   check process nginx with pidfile /var/run/nginx.pid

   141     start program = "/bin/systemctl start nginx"

   142     stop program = "/bin/systemctl stop nginx"

   143 

   144 If process without pid-file::

   145 

   146   check program MyApp with path "systemctl --quiet is-active MyApp"

   147     if status != 0 then ...

   148 

   149 There is a way to tell systemd to create pid-file if process doesn't to it itself::

   150 

   151   ExecStartPost=/bin/sh -c "echo $MAINPID > /run/myapp.pid"

   152 

   153 By matching program name::

   154 

   155   check process MyApp matching 'myapp.*'

   156      start program = /bin/app

   157      stop program = something..

   158 

   159 Can systemd replace monit?

   160 ==========================

   161 

   162 No. Systemd has only basic check if process is running. Imaging that process is stuck. You need some

   163 active probes, like HTTP health endpoint.

   164 

   165 Systemd has limited capabilities for notifying with ``OnFailure``::

   166 

   167   [Service]

   168   Restart=always

   169   RestartSecs=30

   170 

   171   [Unit]

   172   OnFailure=...

   173 

   174 Reverse proxy for monit

   175 =======================

   176 

   177 Ngnix::

   178 

   179   server {

   180     listen   80;

   181     server_name  my.server.name;

   182     location /monit/ {

   183       allow 127.0.0.1;

   184       allow 192.0.0.0/8;

   185       deny all;

   186 

   187       proxy_pass http://127.0.0.1:2812;

   188       proxy_set_header Host $host;

   189       rewrite ^/monit/(.*) /$1 break;

   190       proxy_ignore_client_abort on;

   191     }

   192   }

   193