Super-simple monitoring program.
Effectively all it does is daemonize some programs, re-executing the program on failure, write pidfiles, and provide status checks.
$ make install
Usage: mon [options] <command>
Options:
-V, --version output program version
-h, --help output help information
-l, --log <path> specify logfile [mon.log]
-s, --sleep <sec> sleep seconds before re-executing [1]
-S, --status check status of --pidfile
-p, --pidfile <path> write pid to <path>
-m, --mon-pidfile <path> write mon(1) pid to <path>
-P, --prefix <str> add a log prefix
-d, --daemonize daemonize the program
-e, --on-error <cmd> execute <cmd> on errors
The most simple use of mon(1) is to simply keep a command running:
$ mon ./myprogram
mon : pid 50395
mon : child 50396
mon : sh -c "./example/program.sh"
one
two
three
You may daemonize mon and disassociate from the term with -d:
$ mon ./myprogram -d
mon : pid 50413
mon(1) is designed to monitor a single program only, this means a few things,
firstly that a single mon(1) may crash and it will not influence other programs,
secondly that the "configuration" for mon(1) is simply a shell script,
no need for funky weird inflexible DSLs.
#!/usr/bin/env bash
pids="/var/run"
app="/www/example.com"
mon -d redis-server -p $pids/redis.pid
mon -d "node $app/app" -p $pids/app-0.pid
mon -d "node $app/jobs" -p $pids/jobs-0.pid
mon -d "node $app/jobs" -p $pids/jobs-1.pid
mon -d "node $app/jobs" -p $pids/jobs-2.pid
mon -d "node $app/image" -p $pids/image-0.pid
mon -d "node $app/image" -p $pids/image-1.pid
mon -d "node $app/image-broker" -p $pids/image-broker.pidRestarting a process is simple, kill(1) it. For example if your app is written
to gracefully exit on SIGQUIT you might want to do:
$ kill -s SIGQUIT $(cat /var/run/app-0.pid)
Or if you just want things done quick and dirty:
$ kill -s SIGKILL $(cat /var/run/app-0.pid)
mon(1) will see that the child died, and re-execute
the initial start command.
Tools built with mon(1):
- mongroup(1) - monitor a group of processes