Rails 6.0.0.beta1 can not load database configuration when the URL (or database) is nil

[msdundar]

Steps to reproduce

Here is a part of the database configuration we use:

<% name = 'my_fancy_app'
   url = "postgresql://#{name}:#{name}@localhost/#{name}_%{environment}" %>

default: &default
  adapter: postgresql
  pool: 5
  timeout: 5000
  encoding: unicode

development:
  <<: *default
  url: <%= format url, environment: 'development' %>

test:
  <<: *default
  url: <%= format url, environment: 'test' %>

production: &production
  <<: *default
  url: <%= ENV['DATABASE_URL'] %>
  pool: <%= ENV.fetch('RAILS_MAX_THREADS', 40) %>

beta:
  <<: *production

In Rails 5.2.2 when I call ActiveRecord::Base.configurations['production'] it returns:

{"adapter"=>"postgresql", "pool"=>40, "timeout"=>5000, "encoding"=>"unicode", "url"=>nil}

However, in Rails 6.0.0.beta1 ActiveRecord::Base.configurations['production'] it returns:

nil

Expected behavior

ActiveRecord::Base.configurations should return the existing database variables as it was in Rails 5.2.2.

Actual behavior

Rails 6.0.0.beta1 returns nil when the url (or database) is nil somehow.

System configuration

Rails version:

• Rails 6.0.0.beta1

Ruby version:

Tested with both:

• ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux]
• ruby 2.6.0p0 (2018-12-25 revision 66547) [x86_64-linux]

[gmcgibbon]

Seems to happen when ENV['DATABASE_URL'] is nil on this line. I'll try to fix it.

[msdundar]

Somehow this caused a test suite fail in CircleCI. The logs were stating a fail to read database configuration for beta and production environments, even I can verify ENV['DATABASE_URL'] is defined and accessable. As a workaround I added database: foo_bar line to the configuration and it worked well.

[gmcgibbon]

Given that URL configurations do this, I think this use-case is no longer supported. There's special code for ENV["DATABASE_URL"] that transforms the current environment's config to a URL config, so if you remove the url: setting in production and add database: "", that should work, but that seems like a hack.

cc @eileencodes

[eileencodes]

What does ActiveRecord::Base.configurations return? In Rails 6 configurations aren't a hash, they're an object so ActiveRecord::Base.configurations['production'] won't work anymore. It was an unfortunate change we had to make to improve the overall problem.

You can instead use ActiveRecord::Base.configurations.configs_for(env_name: "production") to get production configurations back.

Eh that wasn't true, I forgot I implemented the ability to use [] with the objects.

[msdundar]

ActiveRecord::Base.configurations.configs_for(env_name: "production") returns nil when the url is nil. However there are other parameters available for the production configuration, and it totally omits them.

• database.yml: As on the issue body.

ActiveRecord::Base.configurations.configs_for(env_name: "development")

=>

[#<ActiveRecord::DatabaseConfigurations::UrlConfig:0x00005568d23caee8
  @config=
   {"adapter"=>"postgresql",
    "pool"=>5,
    "timeout"=>5000,
    "encoding"=>"unicode",
    "username"=>"my_fancy_app",
    "password"=>"my_fancy_app",
    "database"=>"my_fancy_app_development",
    "host"=>"localhost"},
  @env_name="development",
  @spec_name="primary",
  @url="postgresql://nokul:nokul@localhost/nokul_development">]

ActiveRecord::Base.configurations.configs_for(env_name: "production")

=>

nil

I would expect something like this instead of nil when ENV['DATABASE_URL'] is nil:

[#<ActiveRecord::DatabaseConfigurations::UrlConfig:0x00005568d23caee8
  @config=
   {"adapter"=>"postgresql",
    "pool"=>5,
    "timeout"=>5000,
    "encoding"=>"unicode",
    "username"=>"my_fancy_app",
    "password"=>"my_fancy_app",
    "database"=>nil,
    "host"=>nil},
  @env_name="production",
  @spec_name="primary",
  @url=nil>]

[eileencodes]

I'm confused, why are you using the production configuration if the database url isn't set?

[msdundar]

Actually I noticed the changing behavior when I'm trying to make a deploy to Dokku. After the Rails 6.0.0.beta1 upgrade, during the bundle exec rake assets:precompile stage, the container started to complain as follows:

ActiveRecord::AdapterNotSpecified: The `beta` database is not configured for the `beta` environment.

Available databases configurations are:

development
test

We have never changed the database.yml, it is working without any problems when the app in Rails 5.2.2. We only upgraded to Rails 6.0.0 and it started to fail. So I believe that this is something related with the modified behaviour?

[eileencodes]

Ok I was able to reproduce this and am working on a fix. One thing I'd like clarification on is I'm guessing the beta in 5.2 doesn't blow up but doesn't work either because without the database url it would not be able to connect right? Can you tell me what happens with the beta connection in 5.2.2? Thanks!