Replacing "appSettings" configuration section with external file...
A handy trick I frequently show people is to load your global App.Config settings from a separate Config file:
"App.Config" or "Web.Config" file:
<configuration>
<appSettings file="GlobalSettings.Config"/>
</configuration>
"GlobalSettings.Config" file:
<?xml version="1.0" encoding="utf-8" ?>
<appSettings>
<add key="Environment" value="Development" />
<add key="CustomerDBConnectionString" value="..." />
</appSettings>
This can be useful for deploying environment-specific settings, or for a sharing settings across multiple Web.Config files.
NOTE: By doing this, you lose the file-system watcher functions which auto-reload the config file after any change.