Robin Weston Robin Weston - 11 days ago 6
ASP.NET (C#) Question

Best Approach For Configuring Multiple .Net Applications

We have a suite of interlinked .Net 3.5 applications. Some are web sites, some are web services, and some are windows applications. Each app currently has its own configuration file (app.config or web.config), and currently there are some duplicate keys across the config files (which at the moment are kept in sync manually) as multiple apps require the same config value. Also, this suite of applications is deployed across various envrionemnts (dev, test, live etc)

What is the best approach to managing the configuration of these multiple apps from a single configuration source, so configuration values can be shared between multiple apps if required? We would also like to have separate configs for each environment (so when deploying you don't have to manually change certain config values that are environment specific such as conenction strings), but at the same time don't want to maintain multiple large config files (one for each environment) as keeping this in sync when adding new config keys will prove troublesome.

Answer

We use file templates such as MyApp.config.template and MyWeb.config.template with NAnt properties for the bits that are different between environments. So the template file might look a bit like this:

<MyAppConfig>
    <DbConnString>${DbConnString}</DbConnString>
    <WebServiceUri uri="${WebServiceUri}" />
</MyAppConfig>

During a build we generate all the configs for the different environments by just looping through each environment in a NAnt script, changing the value of the NAnt properties ${DbConnString} and ${WebServiceUri} for each environment (in fact these are all set in a single file with sections for each environment), and doing a NAnt copy with the option to expand properties turned on.

It took a little while to get set up but it has paid us back at least tenfold in the amount of time saved messing around with different versions of config files.

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