Why does the "502 Bad Gateway" server error occur when writing to the sqlite3 database on raspberry pi - debian - ruby ​​on rails - Nginx +passenger?

Question

Raspberry Pi

Given:
1) Debian kernel version 3.10.25+.
2) Ruby on Rails.
3) Bundle Nginx + Passenger as a server.
4) I used sqlite3, mysql as db.
The problem is as follows:
I) in the "rails s" debug mode, the server works correctly, but when you upload the application to the nginx server, you can't write to the database. when trying to make a record (sending a post request), nginx issues "502 Bad Gateway"
rights to the production.sqlite3 file set -rw-rw-rw-
II) When changing in the production config, use the filled developmen.sqlite3 database, data from the database is read.
III) for the purity of the experiment, I installed the same configuration on an IBM compatible x86 computer, everything worked on it.
I read on the internet that the problem is in the crooked passengera.
How to track this error in the logs?
Thanks in advance.

Answer 1

Problem with deploying web-server on raspberry PI.
I decided by myself by moving away from "passenger" and switching to "unicorn"
PS: after all, I managed to deploy the "ruby on rails" + "Nginx" + "unicorn" + "mysql" server on Rapberry PI.
information on installing unicorn scooped from here ---> habrahabr.ru/post/120368

Answer 2

How does nginx error to rails? See rail/passenger logs