Extension Model

Alba has an extension model based on this interface:

/// <summary>
/// Models an extension to an AlbaHost
/// </summary>
public interface IAlbaExtension : IDisposable, IAsyncDisposable
{
    /// <summary>
    /// Called during the initialization of an AlbaHost after the application is started,
    /// so the application DI container is available. Useful for registering setup or teardown
    /// actions on an AlbaHOst
    /// </summary>
    /// <param name="host"></param>
    /// <returns></returns>
    Task Start(IAlbaHost host);
        
    /// <summary>
    /// Allow an extension to alter the application's
    /// IHostBuilder prior to starting the application
    /// </summary>
    /// <param name="builder"></param>
    /// <returns></returns>
    IHostBuilder Configure(IHostBuilder builder);
}

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When you are initializing an AlbaHost, you can pass in an optional array of extensions like this sample from the security stub testing:

// This is a Alba extension that can "stub" out authentication
var securityStub = new AuthenticationStub()
    .With("foo", "bar")
    .With(JwtRegisteredClaimNames.Email, "guy@company.com")
    .WithName("jeremy");

// We're calling your real web service's configuration
theHost = await AlbaHost.For<WebAppSecuredWithJwt.Program>(securityStub);

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Configuration Extension

In some scenarios it may be more convienent to override a configuration value rather than modifying the service configuration. Due to a current limitation in the ASP.NET Core test host, overriding your application's configuration values requires a workaround. Alba includes this workaround out of the box via the ConfigurationOverride extension. For example, to override an application's Postgres connection string:

var configValues = new Dictionary<string, string?>()
{
    { "ConnectionStrings:Postgres", "MyOverriddenValue" }
};

var host = await AlbaHost.For<WebAppSecuredWithJwt.Program>(builder =>
{
    builder.ConfigureServices(c =>
    {
        // services config
    });
}, ConfigurationOverride.Create(configValues));

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