Running a Ruby Script from Rails controller kills the rails server

rubyonrails-talk
1

I am trying to run a ruby script from my rails controller.

The script runs successfully when the rails server is started normally as

rails s thin -e development

But when rails server is started as a daemon, the ruby script fails to run.

rails s thin -e development -d

Inside the controller the ruby script is run with the exec command.

script_exec = exec(“ruby /Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper.rb ‘#{city}’ ‘#{date1}’ ‘#{date2}’”)

The above approach kills the rails server and doesn’t execute the ruby script. And hence I used

script_exec = %x{ruby /Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper.rb ‘#{city}’ ‘#{date1}’ ‘#{date2}’ }

script_exec = system(“ruby /Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper.rb ‘#{city}’ ‘#{date1}’ ‘#{date2}’”)

The above %x and system approaches also fail when run rails server is started with -d. But it does work when the rails server is normally.

Hence I tried a different approach of using Daemons

In my controller

file_path1 = “/Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper_control.rb”

script_exec = %x{ruby #{file_path1} start – #{city} #{date1} #{date2}}

The Spreadsheet_proper_control.rb has the

require ‘daemons’

Daemons.run(‘/Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper.rb’)

This approach too fails. Upon logging false value is returned for the above approach.

But when run manually from the terminal, the above Daemon approach is working perfectly.

ruby Spreadsheet_proper_control.rb start – ‘Melbourne’ ‘2015-06-01’ ‘2015-10-01’

The ruby script runs while I am logged into a terminal session and started rails server normally – should that terminal session end so would the server.

Concise app environment:-

  • Ubuntu 14.04

  • Rails version 4.2

  • Ruby 2.2.2

  • daemons (1.2.3)

The Spreadsheet_proper.rb generates an xls file which is then zipped and sent as response by the controller.

Since the output of the ruby script is sent by controller as a response, I couldn’t go for delayed job.

Is there any other approach to run a Ruby script inside Rails controller successfully without the Rails server getting killed when started as daemon?

2

Inside the controller the ruby script is run with the exec command.

script_exec = exec(“ruby /Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper.rb ‘#{city}’ ‘#{date1}’ ‘#{date2}’”)

exec replaces the current process, so this is not surprising

The above approach kills the rails server and doesn’t execute the ruby script. And hence I used

script_exec = %x{ruby /Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper.rb ‘#{city}’ ‘#{date1}’ ‘#{date2}’ }

script_exec = system(“ruby /Code/AttendanceReport/attn/bin/scripts/Spreadsheet_proper.rb ‘#{city}’ ‘#{date1}’ ‘#{date2}’”)

The above %x and system approaches also fail when run rails server is started with -d. But it does work when the rails server is normally.

In what way do they fail?

Fred

3

How do they “fail”? Is there any output in the terminal, in the system log, or the Rails server logs? If you wrap the call in a begin/rescue block, what is the value in $? Example:

exec_result = begin

system(“do a thing”)

rescue => e

$stderr.puts(e.inspect)

$stderr.puts($?)

exit(-1)

end

Also, I’d recommend being VERY CAREFUL with string interpolation around strings that are handed off to the shell (as the one-argument version of system does). If someone enters their city as “; rm -rf / ; echo” you’re going to have a very bad time, depending on your system’s permissions. Prefer the multi-argument version of system whenever possible:

system(“command name”, “arg1”, “arg2”, “arg3”)

In this form, the arguments are passed straight through to the called program, without ever being expanded / manipulated by the shell.

–Matt Jones