Como usar o rails runner com o Gemfile em /var/www/discourse

Tenho um script que precisa carregar alguns dados de um sqlite3 e depois importá-los para o discourse.

rails runner

Presumi que eu poderia usar algo como isto em /shared/add_in_reverse.rb:

require "sqlite3"

# Abrir um banco de dados
db = SQLite3::Database.new "sqlite3.db"

k = 1234
db.execute( "SELECT * from foo where id = ?'", [ k ] ) do |row|
   puts row
end

title = "hello there"
u = User.find_or_create_by(username: "mexample") do |user|
   user.email = "me@example.com"
end
c = Category.find_or_create_by(name: "Something by mexample") do |category|
   category.user = u
end
Topic.create!( title: title, category: c, user: u )

E, então executá-lo com:

rails r /shared/my_custom_script.rb

Mas, isso falha com cannot load such file -- sqlite3 (LoadError)

bundler: failed to load command: script/rails (script/rails)

/usr/local/lib/ruby/site_ruby/3.2.0/rubygems/core_ext/kernel_require.rb:38:in `require': cannot load such file -- sqlite3 (LoadError)
        from /usr/local/lib/ruby/site_ruby/3.2.0/rubygems/core_ext/kernel_require.rb:38:in `require'
        from /var/www/discourse/vendor/bundle/ruby/3.2.0/gems/bootsnap-1.17.0/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:17:in `require'
        from /var/www/discourse/vendor/bundle/ruby/3.2.0/gems/zeitwerk-2.6.12/lib/zeitwerk/kernel.rb:38:in `require'

Gemfile e bundle exec?

Lembrei-me que o ruby às vezes precisa usar Gemfiles? Então, pensei que se eu estivesse no diretório /var/www/discourse, eu poderia prefixar com bundle exec. Mas, isso falha:

#  bundle exec rails r /shared/add_in_reverse.rb
fatal: detected dubious ownership in repository at '/var/www/discourse'
To add an exception for this directory, call:

        git config --global --add safe.directory /var/www/discourse
/var/www/discourse/vendor/bundle/ruby/3.2.0/gems/activerecord-7.0.7/lib/active_record/connection_adapters/postgresql_adapter.rb:81:in `rescue in new_client': We could not find your database: discourse. Which can be found in the database configuration file located at config/database.yml. (ActiveRecord::NoDatabaseError)

To resolve this issue:

- Did you create the database for this app, or delete it? You may need to create your database.
- Has the database name changed? Check your database.yml config has the correct database name.
...

IMPORT=1

Ok. Eu vi alguns exemplos com IMPORT=1. Eu preciso disso?

IMPORT=1 rails r /shared/add_in_reverse.rb
You are trying to install in deployment mode after changing
your Gemfile. Run `bundle install` elsewhere and add the
updated Gemfile.lock to version control.

If this is a development machine, remove the /var/www/discourse/Gemfile freeze 
by running `bundle config unset deployment`.

The list of sources changed
The dependencies in your gemfile changed

You have added to the Gemfile:
* mysql2
* redcarpet
* sqlite3 (~> 1.3, >= 1.3.13)
* ruby-bbcode-to-md
* reverse_markdown
* tiny_tds
* csv
* parallel
# IMPORT=1 bundle exec rails r /shared/add_in_reverse.rb
You are trying to install in deployment mode after changing
your Gemfile. Run `bundle install` elsewhere and add the
updated Gemfile.lock to version control.

If this is a development machine, remove the /var/www/discourse/Gemfile freeze 
by running `bundle config unset deployment`.

The list of sources changed
The dependencies in your gemfile changed

You have added to the Gemfile:
* mysql2
* redcarpet
* sqlite3 (~> 1.3, >= 1.3.13)
* ruby-bbcode-to-md
* reverse_markdown
* tiny_tds
* csv
* parallel

Eu não modifiquei o Gemfile de forma alguma; eu só quero usar o sqlite especificado naquele Gemfile.

Por que dois rails/ruby?

O problema é que o que está no caminho está errado, e eu deveria usar o ruby fornecido? Eu vejo um monte de rubies e rails. Mas usar o fornecido não funciona (ou eu não sei como usá-lo corretamente).

# which ruby
/usr/local/bin/ruby
# which rails
/usr/local/bin/rails
# find /var/www/discourse/ | grep ruby | grep vendor | grep bin | grep rails
/var/www/discourse/vendor/bundle/ruby/3.2.0/bin/rails

# /var/www/discourse/vendor/bundle/ruby/3.2.0/bin/rails runner /shared/add_in_reverse.rb
/usr/local/lib/ruby/site_ruby/3.2.0/rubygems.rb:264:in `find_spec_for_exe': can't find gem railties (>= 0.a) with executable rails (Gem::GemNotFoundException)
        from /usr/local/lib/ruby/site_ruby/3.2.0/rubygems.rb:283:in `activate_bin_path'
        from /var/www/discourse/vendor/bundle/ruby/3.2.0/bin/rails:25:in `<main>'

Acho que posso usar crases com o binário do sqlite? Afinal, estou recebendo apenas uma linha. Mas, estou intrigado por que o que estou tentando fazer não é fácil. Pensei que o sqlite fosse o banco de dados padrão para todos os novos projetos Rails. Ele foi desativado intencionalmente para o Discourse?