.NET Configuration (app.config/web.config/settings.settings)

Question

I have a .NET application which has different configuration files for Debug and Release builds. E.g. the debug app.config file points to a development SQL Server which has debugging enabled and the release target points to the live SQL Server. There are also other settings, some of which are different in debug/release.

I currently use two separate configuration files (debug.app.config and release.app.config). I have a build event on the project which says if this is a release build then copy release.app.config to app.config, else copy debug.app.config to app.config.

The problem is that the application seems to get its settings from the settings.settings file, so I have to open settings.settings in Visual Studio which then prompts me that the settings have changed so I accept the changes, save settings.settings and have to rebuild to make it use the correct settings.

Is there a better/recommended/preferred method for achieving a similar effect? Or equally, have I approached this completely wrong and is there a better approach?

Answer 1

Any configuration that might differ across environments should be stored at the machine level, not the application level. (More info on configuration levels.)

These are the kinds of configuration elements that I typically store at the machine level:

• Application settings
• Connection strings
• retail=true
• Smtp settings
• Health monitoring
• Hosting environment
• Machine key

When each environment (developer, integration, test, stage, live) has its own unique settings in the c:\Windows\Microsoft.NET\Framework64\v2.0.50727\CONFIG directory, then you can promote your application code between environments without any post-build modifications.

And obviously, the contents of the machine-level CONFIG directory get version-controlled in a different repository or a different folder structure from your app. You can make your .config files more source-control friendly through intelligent use of configSource.

I've been doing this for 7 years, on over 200 ASP.NET applications at 25+ different companies. (Not trying to brag, just want to let you know that I've never seen a situation where this approach doesn't work.)

Answer 2

This might help some people dealing with Settings.settings and App.config: Watch out for GenerateDefaultValueInCode attribute in the Properties pane while editing any of the values in the Settings.settings grid in Visual Studio (Visual Studio 2008 in my case).

If you set GenerateDefaultValueInCode to True (True is the default here!), the default value is compiled into the EXE (or DLL), you can find it embedded in the file when you open it in a plain text editor.

I was working on a console application and if I had defaulted in the EXE, the application always ignored the configuration file placed in the same directory! Quite a nightmare and no information about this on the whole Internet.