Source DB config more cleanly, fixes issues with socket in prd

app/models/global_setting.rb

@@ -16,6 +16,19 @@ class GlobalSetting
     end
   end
 
+  def self.database_config
+    hash = {"adapter" => "postgresql"}
+    %w{pool timeout socket host port username password}.each do |s|
+      if val = self.send("db_#{s}")
+        hash[s] = val
+      end
+    end
+    hash["host_names"] = [ hostname ]
+    hash["database"] = db_name
+
+    {"production" => hash}
+  end
+
 
   class BaseProvider
     def self.coerce(setting)

config/application.rb

@@ -8,10 +8,21 @@ require_relative '../lib/discourse_plugin_registry'
 require_relative '../app/models/global_setting'
 
 if defined?(Bundler)
-  # If you precompile assets before deploying to production, use this line
   Bundler.require(*Rails.groups(assets: %w(development test profile)))
-  # If you want your assets lazily compiled in production, use this line
-  # Bundler.require(:default, :assets, Rails.env)
+end
+
+# PATCH DB configuration
+class Rails::Application::Configuration
+
+  def database_configuration_with_global_config
+    if Rails.env == "production"
+      GlobalSetting.database_config
+    else
+      database_configuration_without_global_config
+    end
+  end
+
+  alias_method_chain :database_configuration, :global_config
 end
 
 module Discourse

config/database.yml

@@ -33,15 +33,8 @@ profile:
   host_names:
     - "localhost"
 
-production:
-  pool: <%= GlobalSetting.db_pool %>
-  timeout: <%= GlobalSetting.db_timeout %>
-  adapter: postgresql
-  socket: <%= GlobalSetting.db_socket %>
-  host: <%= GlobalSetting.db_host %>
-  port: <%= GlobalSetting.db_port %>
-  database: <%= GlobalSetting.db_name %>
-  username: <%= GlobalSetting.db_username %>
-  password: <%= GlobalSetting.db_password %>
-  host_names:
-    - <%= GlobalSetting.hostname %>
+# You may be surprised production is not here, it is sourced from application.rb using a monkey patch
+# This is done for 2 reasons
+#
+# 1. we need to support blank settings correctly and rendering nothing in yaml/erb is a PITA
+# 2. why go from object -> yaml -> object, pointless