Module progress 

Progress reporting interface for command workflows

This module defines the CommandProgressListener trait that enables application-layer command handlers to report progress to the user interface without depending on presentation-layer types.

DDD Layer Placement

• Defined in: Application layer (src/application/traits/)
• Implemented in: Presentation layer (src/presentation/)
• Dependency direction: Presentation → Application (correct)

The trait lives here because it’s a use-case concern: progress reporting is about orchestrating steps in a command workflow, which is the application layer’s responsibility. The presentation layer implements the trait to translate progress events into user-facing output.

Verbosity Mapping

The listener methods map to verbosity levels (but the listener itself does not know about verbosity — that’s the implementation’s concern):

• on_step_started / on_step_completed → Verbose (-v)
• on_detail → VeryVerbose (-vv)
• on_debug → Debug (-vvv)

The application layer reports everything; the presentation layer filters based on the user’s chosen verbosity level.

Example

use torrust_tracker_deployer_lib::application::traits::CommandProgressListener;

async fn execute(
    &self,
    env_name: &EnvironmentName,
    listener: Option<&dyn CommandProgressListener>,
) -> Result<(), Error> {
    if let Some(l) = listener {
        l.on_step_started(1, 3, "Rendering templates");
    }
    // ... perform step ...
    if let Some(l) = listener {
        l.on_step_completed(1, "Rendering templates");
    }
    Ok(())
}

Structs

NullProgressListener

A no-op listener that discards all progress events.

Traits

CommandProgressListener

A listener for reporting command progress to the user interface.