Monit bundle exec rails s

问题

I have the following shell script that allows me to start my rails app, let's say it's called start-app.sh:

#!/bin/bash

cd /var/www/project/current
. /home/user/.rvm/environments/ruby-2.3.3
RAILS_SERVE_STATIC_FILES=true RAILS_ENV=production nohup bundle exec rails s -e production -p 4445 > /var/www/project/log/production.log 2>&1 &

the file above have permissions of:

-rwxr-xr-x  1 user user   410 Mar 21 10:00 start-app.sh*

if i want to check the process I do the following:

ps aux | grep -v grep | grep ":4445"

it'd give me the following output:

user  2960  0.0  7.0 975160 144408 ?       Sl   10:37   0:07 puma 3.12.0 (tcp://0.0.0.0:4445) [20180809094218]

P.S: the reason i grep ":4445" is because i have few processes running on different ports. (for different projects)

now coming to monit, i used apt-get to install it, and the latest version from repo is 5.16, as i'm running on Ubuntu 16.04, also note that monit is running as root, that's why i specified the gid uid in the following. (because the start script is used to be executed from "user" and not "root")

Here's the configuration for monit:

  set daemon 20            # check services at 20 seconds interval
  set logfile /var/log/monit.log
  set idfile /var/lib/monit/id
  set statefile /var/lib/monit/state


  set eventqueue
      basedir /var/lib/monit/events # set the base directory where events will be stored
      slots 100                     # optionally limit the queue size


  set mailserver xx.com port xxx
      username "xx@xx.com" password "xxxxxx"
      using tlsv12
      with timeout 20 seconds

  set alert xx@xx.com


  set mail-format {
       from: xx@xx.com
    subject: monit alert -- $EVENT $SERVICE
    message: $EVENT Service $SERVICE
                    Date:  $DATE
                  Action:  $ACTION
                    Host:  $HOST
             Description:  $DESCRIPTION
  }

 set limits {
        programOutput:     51200 B
        sendExpectBuffer:  25600 B
        fileContentBuffer: 51200 B
        networktimeout:    10 s
 }

  check system $HOST
    if loadavg (1min) > 4 then alert
    if loadavg (5min) > 2 then alert
    if cpu usage > 90% for 10 cycles then alert
    if memory usage > 85% then alert
    if swap usage > 35% then alert

check process nginx with pidfile /var/run/nginx.pid
        start program = "/bin/systemctl start nginx"
        stop program = "/bin/systemctl stop nginx"


check process redis
        matching "redis"
        start program = "/bin/systemctl start redis"
        stop program = "/bin/systemctl stop redis"

check process myapp
    matching ":4445"
    start program = "/bin/bash -c '/home/user/start-app.sh'" as uid "user" and gid "user"
    stop program = "/bin/bash -c /home/user/stop-app.sh" as uid "user" and gid "user"

   include /etc/monit/conf.d/*
   include /etc/monit/conf-enabled/*

Now monit, is detecting and alerting me when the process goes down (if i kill it manually) and when it's manually recovered, but it won't start that shell script automatically.. and according to /var/log/monit.log, it's showing the following:

[UTC Aug 13 10:16:41] info     : Starting Monit 5.16 daemon
[UTC Aug 13 10:16:41] info     : 'production-server' Monit 5.16 started
[UTC Aug 13 10:16:43] error    : 'myapp' process is not running
[UTC Aug 13 10:16:46] info     : 'myapp' trying to restart
[UTC Aug 13 10:16:46] info     : 'myapp' start: /bin/bash
[UTC Aug 13 10:17:17] error    : 'myapp' failed to start (exit status 0) -- no output

So far what I see when monit tries to execute the script is that it tries to load it (i can see it for less than 3 seconds using ps aux | grep -v grep | grep ":4445", but this output is different from the above output i showed up, it shows the content of the shell script being executed and specifically this one:

blablalba... nohup bundle exec rails s -e production -p 4445

and then it disappears. then it tries to re-execute the shell.. again and again... What am I missing, and what is wrong with my configuration? note that I can't change anything in the start-app.sh because it's on production and working 100%. (i just want to monitor it)

Edit: To my understanding and experience, it seems to be a Environment Variable issue or path issue, but i'm not sure how to solve it, it doesn't make any sense to put the env variables inside monit .. what if someone else wanted to edit that shell script or add something new? i hope you get my point

回答1:

As i expected, it was user-environment issue and i solved it by editing monit configuration as below:

Before (not working)

check process myapp
    matching ":4445"
    start program = "/bin/bash -c '/home/user/start-app.sh'" as uid "user" and gid "user"
    stop program = "/bin/bash -c /home/user/stop-app.sh" as uid "user" and gid "user"

After (working)

check process myapp
    matching ":4445"
    start program = "/bin/su -s /bin/bash -c '/home/user/start-app.sh' user"
    stop program = "/bin/su -s /bin/bash -c '/home/user/stop-app.sh' user"

Explanation: i removed (uid and gid) as "user" from monit because it will only execute the shell script in the name of "user" but it won't get/import/use user's env path, or env variables.

来源：https://stackoverflow.com/questions/51825517/monit-bundle-exec-rails-s

标签

ruby-on-rails

Linux

bash

nohup

monit