Node.js/Ruby applications do not work if CageFS is enabled for the subscription user

Symptoms

• CloudLinux 6 or 7 is used on the server

• CageFS is enabled for the subscription's user in Extensions > My Extensions > CageFS > Open

• HTTP code 500 is returned by the website with the application deployed on it:

  # curl -skIL https://node.example.com/
  HTTP/1.1 500 external Server Error
  Server: nginx
  Date: Tue, 23 Apr 2019 04:30:29 GMT
  Status: 500 Internal Server Error

• The following error can be found on the page on attempt to open it:

  We're sorry, but something went wrong.
  The issue has been logged for investigation. Please try again later.

  Web application could not be started by the Phusion Passenger application server.

• The following error messages can be found in the Apache Web Server log file /var/log/httpd/error_log, or in nginx log file /var/log/nginx/error.log:

  [ E 2019-07-04 05:05:57.4448 42423/Tb age/Cor/App/Implementation.cpp:221 ]: Could not spawn process for application /var/www/vhosts/example.com/httpdocs: The application process exited prematurely.
  Error ID: 2daff851
  Error details saved to: /tmp/passenger-error-jmYMVA.html

  [ E 2019-07-04 05:05:57.4534 42423/T5 age/Cor/Con/CheckoutSession.cpp:276 ]: [Client 1-1] Cannot checkout session because a spawning error occurred. The identifier of the error is 2daff851. Please see earlier logs for details about the error.

• Following can be found in /tmp/systemd-private-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-httpd.service-XXXXXX/tmp/passenger-error-XXXXXX.html, or /tmp/passenger-error-XXXXXX.html:

  "stdout_and_err" : "Warning: cannot open /tmp/passenger.spawn.XXXXh6sP7q/envdump/user_info for writingnWarning: cannot open /tmp/passenger.spawn.XXXXh6sP7q/envdump/envvars for writingnWarning: cannot open /tmp/passenger.spawn.XXXXh6sP7q/envdump/user_info for writingn
  <...>

Cause

Phusion Passenger creates a socket to communicate with Node.js and Ruby applications in /tmp/ directory. This directory is overridden by the private per-user /tmp/ created by CageFS.

Resolution

Configure NodeJS to work with CageFS.