Overriding app.config settings

NServiceBus uses the running process config file as its default source of configuration. Both the default behavior and the location from where the configuration is loaded can be changed. This can be done for the whole configuration or specific sections.

Overriding an app.config section

A configuration for a specific section can be overridden using the IProvideConfiguration<T> interface. For example, rather than providing the RijndaelEncryptionServiceConfig in app.config the code below provides an alternative configuration that will be used as long as RijndaelEncryptionServiceConfig is found in the types scanned:

class CustomRijndaelEncryptionServiceConfigProvider :
    IProvideConfiguration<RijndaelEncryptionServiceConfig>
{
    public RijndaelEncryptionServiceConfig GetConfiguration()
    {
        return new RijndaelEncryptionServiceConfig
        {
            Key = "gdDbqRpqdRbTs3mhdZh9qCaDaxJXl+e6"
        };
    }
}

Code-only configuration

If the endpoint must load its configuration from a source other than the 'app.config', an implementation of the IConfigurationSource interface can be registered as a custom configuration source. This approach enables retrieving the configuration from any location, such as a database or a web service.

Registering custom configuration source

This code instructs NServiceBus to use MyCustomConfigurationSource as a custom configuration source:

busConfiguration.CustomConfigurationSource(new MyCustomConfigurationSource());

Providing configuration from a custom location (other than app.config)

The GetConfiguration method provides data for RijndaelEncryptionServiceConfig directly in code, while allowing all other configuration sections to be retrieved from the config file.

public class MyCustomConfigurationSource :
    IConfigurationSource
{
    public T GetConfiguration<T>() where T : class, new()
    {
        if (typeof(T) == typeof(RijndaelEncryptionServiceConfig))
        {
            var config = new RijndaelEncryptionServiceConfig
            {
                Key = "gdDbqRpqdRbTs3mhdZh9qCaDaxJXl+e6"
            };
            return config as T;
        }
        // leave the rest of the configuration as is:
        return ConfigurationManager.GetSection(typeof(T).Name) as T;
    }
}