Writing Extension Commands #

Oakton has a strong extensibility model to find and activate commands from external assemblies. If an application uses the RunOaktonCommands(args) method, Oakton will look for any Oakton commands in any assembly that has this assembly level attribute:

[assembly:Oakton.OaktonCommandAssembly]

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Extension commands can be either basic OaktonCommand or OaktonAsyncCommand classes. To add an extension command that uses the HostBuilder configuration of the application, the command needs to use the NetCoreInput class or a class that inherits from NetCoreInput. In this simple example below, I've built a command that just tries to do a "smoke test" by calling the HostBuilder.Build() method and seeing if any exceptions happen:

[Description("Simply try to build a web host as a smoke test", Name = "smoke")]
public class SmokeCommand : OaktonCommand<NetCoreInput>
{
    public override bool Execute(NetCoreInput input)
    {
        // This method builds out the IWebHost for your
        // configured IHostBuilder of the application
        using (var host = input.BuildHost())
        {
            Console.WriteLine("It's all good");
        }

        return true;
    }
}

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The NetCoreInput carries the IHostBuilder of your application, but does not start up or build the IHost by itself. You would have to explicitly do so, but making that lazy gives you the ability to alter or extend the application configuration before calling IHostBuilder.Build() or IHostBuilder.Start().