What is the best way to expose/promote to ENV

[jhirn]

I have a gem that depends on some things set in ENV. For local development I want them to come from secrets.yml, but I have to set ENV.

It kinda feels like adding everything in the configuration to ENV would be useful, but heavy handed. I've considered adding an on_load to my ApplicationConfig but would want to expose a macro for which things to expose. Also want to add them to env in the way that AnywayConfig would respect (e.g. env_prefix, underscore rules) but havn't found a helper method for generating them based on config_attributes.

This is what I'd like to see and will probably write for my app, but figured I'd ask in case I missed a feature that already exists.

class MyConfig < ApplicationController
   attr_config :thing
   expose_to_env :thing # Sets ENV['MY_THING']
end

[palkan]

Hey!
As I understand, you're looking for something like:

config = MyConfig.new # loads data from wherever

config_env = config.to_env #=> { 'MY_CONFIG_X' => ... }

ENV.merge!(config_env)

WDYT? We can add #to_env support (I see how it can be useful to debug configurations, not only to deal with third-party libraries)

[jhirn]

Thank you for entertaining this idea.

Here is the module I've written so far.

# frozen_string_literal: true

module EnvPromotable
  extend ActiveSupport::Concern

  included do
    cattr_accessor :promoted_attrs
    self.promoted_attrs = []
  end

  class_methods do
    def promote_to_env(*attrs)
      self.promoted_attrs = attrs
      attrs_to_env
    end

    def attrs_to_env
      promoted_attrs.each do |attr|
        value = send(attr)
        key = [env_prefix,attr].join("_").upcase
        ENV[key] = value.to_s unless value.nil?
      end
    end
  end
end

class GoogleConfig < ApplicationConfig
  include EnvPromotable

  attr_config :account_type, :client_id, :client_email, :private_key
  promote_to_env :client_id, :private_key
end

.to_env would definitely be helpful. .to_env_name might also be helpful (either MyConfig.attr_to_env_name or MyConfig.to_env_name(attr).

I'd like to only promote some of the keys, but it's not really a big deal.

The obstacle with this approach is initialization and potentially reloading. The attribute is not promoted until the config/class is loaded which doesn't work without eager loading. Is there a way to force eager loading of config classes in the gem? I can write an initializer or block in application.rb, not sure which is best, but was hoping to have it all contained in a module.

W.R.T. reloading I want to make sure setting the attr and a new instance/reload would update the ENV. These two aren't strictly my use case but it makes sense to have them in sync, although could get weird working with multiple instances for testing or wonky use-cases. Plus ENV reloads are understood a restart is required so maybe reloading isn't good idea? I tried to use a proc for the ENV value but it didnt' seem to like that (e.g. ENV["GOOGLE_CLIENT_ID"]= -> {GoogleConfig.google_client_id})

[jhirn]

This is the solution I'm running with for now.

module EnvPromotable
  extend ActiveSupport::Concern

  included do
    cattr_accessor :promoted_attrs
    self.promoted_attrs = []

    def attrs_to_env
      puts "Promoting #{promoted_attrs}"
      promoted_attrs.each do |attr|
        value = send(attr)
        key = [env_prefix,attr].join("_").upcase
        ENV[key] = value.to_s unless value.nil?
      end
    end

    on_load :attrs_to_env
  end

  class_methods do
    def promote_to_env(*attrs)
      self.promoted_attrs = attrs
      attrs_to_env
    end
  end
end

It works with rspec but in order for envs to be populated in a fresh rails console I added this to application.rb

unless Rails.application.config.eager_load
      ActiveSupport::Reloader.to_prepare do
        [
          "config/configs/*.rb",
           ...
        ].each do |eager_with_reload_directory|
          Dir[eager_with_reload_directory].each do |f|
            require_dependency("#{Dir.pwd}/#{f}")
          rescue StandardError => e
            puts e.backtrace.take(10)
            puts "\nError requiring local file\n\ #{f}\n#{e}\n\n"
            nil
          end
        end
      end
    end

Not pretty but we already had this block for some other STI classes and it does seem to work. It also runs all validations when starting the console so you know if things are wonky before using them.