Backport Rails 6 per-environment credentials to Rails 5.2

Rails PR: https://github.com/rails/rails/pull/33521

This patch makes it possible to use per-environment credentials (i.e., config/credentials/staging.yml.enc) in Rails 5.2.

Installation

• Drop backport_rails_six_credentials.rb and backport_rails_six_credentials_command.rb somewhere, for example, into the lib/ folder
• Add this line to config/application.rb:

# Right after `require "rails"`

require_relative "../lib/backport_rails_six_credentials"

• Add this line to config/boot.rb:

# Right after `require 'bundler/setup'`
require_relative "../lib/backport_rails_six_credentials_command"

Usage

Now you can call:

$ bundle exec rails credentials:edit -e staging

create  config/credentials/staging.key
...

And Rails.application.credentials now uses env-specific credentials if they're present and master/root credentials otherwise.