Configuration alternative needed when db connection is configured with DATABASE_URL

[serggiu]

This has been flagged in another issue but wasn't pursued because the author did not provide enough info.

When the database connection is configured using the DATABASE_URL ENV var, we cannot overwrite the adapter option by simply mentioning it in the database.yml.
In this case, the logic to extract the connection details is coming from ActiveRecord::DatabaseConfigurations::UrlConfig which doesn't use any other options given in database.yml.

Trying to overwrite the protocol part from DATABASE_URL, something like:

ENV['DATABASE_URL'].gsub("postgresql", "postgresql_proxy")

will not work because postgresql_proxy is not considered valid inside the URL, especially at the protocol level.

I can see two options here, but please let me know if you see any other:

Option 1: along with postgresql_proxy, also allow postgresqlproxy (one word, no _ char which is considered invalid char in a URL) to trigger the switch to the proxy adapter.

Option 2: update the Readme with an alternative option to switch to the proxy adapter, maybe in an initializer, something like this:

# inside config/initializers/active_record_proxy_adapters.rb

if ENV['PRIMARY_DATABASE_ADAPTER'] == 'postgresql_proxy'
  # proxy adapter initialization code goes here
end

# the rest of the configuration
ActiveRecordProxyAdapters.configure do |config|
  # ...
end

The workaround I'm using now is derived from your suggestion in Issue 136. I've updated the database.yml like this:

  development:
    adapter: <%= ENV.fetch("PRIMARY_DATABASE_ADAPTER", "postgresql") %>
    host: <%= URI(ENV['DATABASE_URL']).host %>
    port: <%= URI(ENV['DATABASE_URL']).port %>
    database: <%= URI(ENV['DATABASE_URL']).path.sub(%r{^/}, '') %>
    username: <%= URI(ENV['DATABASE_URL']).user %>
    password: <%= URI(ENV['DATABASE_URL']).password %>
    url:

The empty url: part is needed to overwrite the usage of the DATABASE_URL ENV var. It does work but it's not the most elegant solution.

I think that updating the gem documentation with an option for this situation would offer a solution to those using Heroku or other similar platforms.

Please let me know your thoughts on this, thank you!

[mateuscruz]

Hey @serggiu.

Option 1: along with postgresql_proxy, also allow postgresqlproxy (one word, no _ char which is considered invalid char in a URL) to trigger the switch to the proxy adapter.

You can make that work by adding this single line to your application config:

ActiveRecord.protocol_adapters[:postgresqlproxy] = 'postgresql_proxy'

I have thought about adding that to gem by default but, the reason I haven't done so yet, is because that would mislead users into thinking postgresqlproxy is an actual Postgres protocol. However, if that works for you, you can add that line to your config and you should be all set.

Option 2: update the Readme with an alternative option to switch to the proxy adapter, maybe in an initializer, something like this:

That option won't work because ActiveRecord::Base.configurations is the single source of truth for all connection configurations globally. And that is loaded at application bootstrap by a railtie from config/database.yml. ActiveRecord is the one responsible for finding the appropriate adapter and settings with the configuration provided. All other gems that extend ActiveRecord will expect that convention and doing it a different way here would break things for a lot of folks. That is why I suggested an example of a URI resolver to be used in the YAML file.

I think that updating the gem documentation with an option for this situation would offer a solution to those using Heroku or other similar platforms.

PRs are welcome :)

[mateuscruz]

[1] pry(main)> ActiveRecord.protocol_adapters[:postgresqlproxy] = 'postgresql_proxy'
=> "postgresql_proxy"
[2] pry(main)> ActiveRecord::DatabaseConfigurations::ConnectionUrlResolver.new('postgresqlproxy://gandalf:mellon@localhost:5432/walls_of_moria').to_hash
=> {adapter: "postgresql_proxy", username: "gandalf", password: "mellon", port: 5432, database: "walls_of_moria", host: "localhost"}
[3] pry(main)>