Monit fails to start process

问题:

I've written a scrip that works fine to start and stop a server.

#!/bin/bash  PID_FILE='/var/run/rserve.pid'  start() {        touch $PID_FILE        eval "/usr/bin/R CMD Rserve"        PID=$(ps aux | grep Rserve | grep -v grep | awk '{print $2}')        echo "Starting Rserve with PID $PID"        echo $PID > $PID_FILE } stop () {        pkill Rserve        rm $PID_FILE        echo "Stopping Rserve" }  case $1 in     start)        start        ;;     stop)          stop        ;;      *)          echo "usage: rserve {start|stop}" ;;  esac  exit 0 

If I start it by running

rserve start 

and then start monit it will correctly capture the PID and the server:

The Monit daemon 5.3.2 uptime: 0m   Remote Host 'localhost'   status                            Online with all services   monitoring status                 Monitored   port response time                0.000s to localhost:6311 [DEFAULT via TCP]   data collected                    Mon, 13 May 2013 20:03:50  System 'system_gauss'   status                            Running   monitoring status                 Monitored   load average                      [0.37] [0.29] [0.25]   cpu                               0.0%us 0.2%sy 0.0%wa   memory usage                      524044 kB [25.6%]   swap usage                        4848 kB [0.1%]   data collected                    Mon, 13 May 2013 20:03:50 

If I stop it, it will properly kill the process and unmonitor it. However if I start it again, it won't start the server again:

ps ax | grep Rserve | grep -vc grep 1 monit stop localhost ps ax | grep Rserve | grep -vc grep 0 monit start localhost  [UTC May 13 20:07:24] info     : 'localhost' start on user request [UTC May 13 20:07:24] info     : monit daemon at 4370 awakened [UTC May 13 20:07:24] info     : Awakened by User defined signal 1 [UTC May 13 20:07:24] info     : 'localhost' start: /usr/bin/rserve [UTC May 13 20:07:24] info     : 'localhost' start action done [UTC May 13 20:07:34] error    : 'localhost' failed, cannot open a connection to INET[localhost:6311] via TCP 

Here is the monitrc:

check host localhost with address 127.0.0.1   start = "/usr/bin/rserve start"   stop = "/usr/bin/rserve stop"   if failed host localhost port 6311 type tcp with timeout 15 seconds for 5 cycles     then restart 

回答1:

I had problem start or stop process via shell too. One solution might be add "/bin/bash" in the config like this:

start program = "/bin/bash /urs/bin/rserv start" stop program = "/bin/bash /urs/bin/rserv stop" 

It worked for me.

回答2:

monit is a silent killer. It does not tell you anything. Here are things I would check which monit won't help you identify

1. Check permissions of all the files you are reading / writing. If you are redirecting output to a file, make sure that file is writable by uid and gid you are using to execute the program
2. Again check exec permission on the program you are trying to run
3. Specify full path to any program you are trying to execute ( not strictly necessary, but you don't have to worry about path not being set if you always specify full path )
4. Make sure you can run the program outside of monit without any error before trying to investigate why monit is not starting.

回答3:

When monit starts it checks for its own pidfile and checks if the process with matching PID is running already - if it does, then it just wakes up this process.

in your case, check if this pid is being used by some other process: ps -ef |grep 4370

if yes, then you need to remove the below file(usually under /run directory) and start monit again: monit.pid

回答4:

If the Monit log is displaying

failed to start (exit status -1) -- no output 

Then it may be that you're trying to run a script without any of the Bash infrastructure. You can run such a command by wrapping it in /bin/bash -c, like so:

check process my-process   matching "my-process-name"   start program = "/bin/bash -c '/etc/init.d/my-init-script'" 

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