Describe Command

The describe command outputs a summary of your application's configuration and registered components. It is built in and available automatically.

Running Describe

dotnet run -- describe

This prints information about all registered ISystemPart instances, including those added by Critter Stack libraries like Marten and Wolverine.

Custom System Parts

Implement ISystemPart to add your own sections to the describe output:

public class MessagingSystemPart : SystemPartBase
{
    public MessagingSystemPart()
        : base("Messaging Subsystem", new Uri("system://messaging"))
    {
    }

    public override Task WriteToConsole()
    {
        AnsiConsole.MarkupLine("[bold]Transport:[/] RabbitMQ");
        AnsiConsole.MarkupLine("[bold]Queues:[/] 12 active");
        AnsiConsole.MarkupLine("[bold]Consumers:[/] 8 running");
        return Task.CompletedTask;
    }
}

^{snippet source | anchor}

public class MessagingSystemPart : SystemPartBase
{
    public MessagingSystemPart()
        : base("Messaging Subsystem", new Uri("system://messaging"))
    {
    }

    public override Task WriteToConsole()
    {
        AnsiConsole.MarkupLine("[bold]Transport:[/] RabbitMQ");
        AnsiConsole.MarkupLine("[bold]Queues:[/] 12 active");
        AnsiConsole.MarkupLine("[bold]Consumers:[/] 8 running");
        return Task.CompletedTask;
    }
}

^{snippet source | anchor}

Register your system part through JasperFxOptions:

services.AddJasperFx(opts =>
{
    opts.Services.AddSingleton<ISystemPart, MessagingSystemPart>();
});

IDescriptionWriter

The IDescriptionWriter interface provides methods for structured output:

Method	Purpose
BulletItem(string)	Write a bullet point
Header(string)	Write a section header
Write(string)	Write plain text

Built-in System Parts

JasperFx itself registers a system part for JasperFxOptions that reports:

• Active profile (Development, Staging, Production)
• Required files
• Registered environment checks

Other Critter Stack libraries add their own parts automatically when referenced.

Next Steps

• Environment Checks -- Validate dependencies at startup
• JasperFx Options -- Full options reference