Change or disable the default call to ActiveRecord::Base.establish_connection

rubyonrails-talk
1

Is there any way to change or prevent the default call to ActiveRecord::Base.establish_connection?

I was expecting to find it in config/application.rb or an env specific configuration file, but I can’t find it.

What is the proper way to customize the behavior?

I need something similar to this:

if ENV['PROCNAME'] == 'worker-without-db'
  # do not connect to db
else
  ActiveRecord::Base.establish_connection = "my database"
end

In this way I could prevent the call to establish_connection for a large number of sidekiq processes that never need DB access (in order to avoid hundreds of useless DB connections).

2

Active Record shouldn’t be connecting to the database until something happens that requires the connection.

If your processes are consuming connections, perhaps you can track down where it’s being used?

3

I think that you are correct.

However it would be extremely important for us to have a way to prevent that (by accident)…

Basically most of our background workers only need access to Redis and I was looking for a way to prevent accidental connections to the db. It was interesting if there was an option inside ActiveRecord… Something like .freeze (as a metaphor), but that says to AR to disable all the db connections.

4

First thing that came to my mind is to set DATABASE_URL environment variable to something dummy that would throw an error on connection attempt.

You could also instead require "rails/all" in config/application.rb require only railties that you actually need (not require active record for worker) but that will mean that you should skip all your models also …