feat: Add destroy subcommand to CLI with UserOutput system

[Copilot]

Overview

This PR implements the destroy subcommand in the CLI with a new UserOutput system for user-facing messages, completing the UI layer for the destroy command workflow.

Changes

UserOutput System (src/shared/user_output.rs)

Implemented a dual-channel output system following Unix conventions and modern CLI best practices (cargo, docker, npm):

• VerbosityLevel enum: Five levels (Quiet, Normal, Verbose, VeryVerbose, Debug) with proper ordering
• UserOutput struct: Dual writers separating concerns:
  • stderr: Progress updates, status messages, warnings, errors
  • stdout: Final results and structured data for piping/redirection
• Benefits:
  • Clean piping: torrust-tracker-deployer destroy env 2>/dev/null captures only results
  • Automation friendly: Scripts can redirect channels independently
  • Follows established CLI tool patterns

CLI Integration (src/app.rs)

Added destroy subcommand with complete integration:

• Commands enum: New Destroy variant accepting environment parameter
• Command handler: handle_destroy_command() function that:
  • Validates environment names with clear error messages
  • Loads environments from persistent storage
  • Executes DestroyCommandHandler from application layer
  • Provides user-friendly progress updates using UserOutput
  • Handles all error cases with actionable guidance

Example Usage

# Get help
torrust-tracker-deployer destroy --help

# Destroy an environment
torrust-tracker-deployer destroy e2e-provision
⏳ Destroying environment 'e2e-provision'...
⏳ Tearing down infrastructure...
⏳ Cleaning up resources...
✅ Environment 'e2e-provision' destroyed successfully

# Error handling
torrust-tracker-deployer destroy "invalid name!"
❌ Invalid environment name 'invalid name!': contains invalid characters: !

Testing

• Unit tests: 23 new tests (14 UserOutput + 9 CLI parsing)
• All tests passing: 852 total tests (843 library + 9 binary)
• Channel separation: Tests verify stdout/stderr usage with buffer writers
• Verbosity behavior: Tests verify message filtering at different levels
• CLI parsing: Tests cover argument validation, defaults, and error cases

Code Quality

• ✅ All linters passing (markdown, yaml, toml, cspell, clippy, rustfmt, shellcheck)
• ✅ Code formatted with cargo fmt
• ✅ All clippy warnings addressed
• ✅ Comprehensive documentation with examples

Dependencies

⚠️ Manual E2E testing blocked by #21 (Fix E2E Infrastructure Preservation)

Full end-to-end testing with actual infrastructure requires the --keep flag from Issue #21 to preserve E2E test environments. The CLI is functionally complete and ready for use once that dependency is resolved.

Related Issues

• Closes Add Clap Subcommand Configuration #23
• Part of Epic EPIC: UI Layer Destroy Command #10 (UI Layer Destroy Command)
• Depends on Fix E2E Infrastructure Preservation #21 (for manual E2E testing only)
• Related to Rename App Commands to Command Handlers #22 (Command Handler terminology)

Documentation

See docs/issues/23-add-clap-subcommand-configuration.md for full specification and docs/research/UX/console-app-output-patterns.md for channel strategy research.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add Clap Subcommand Configuration</issue_title>
<issue_description># Add Clap Subcommand Configuration

Type: Task
Priority: High
Parent Epic: #10 - UI Layer Destroy Command
Dependencies: #21 - MUST BE COMPLETED FIRST (E2E Infrastructure Preservation)
Estimated Effort: 3-4 hours

---

📋 Issue Overview

Implement the destroy subcommand in the CLI with basic functionality and UserOutput scaffolding. This creates the user-facing interface that calls the DestroyCommandHandler from the application layer.

🔗 Dependencies

Blocking Dependency: Issue #21 (Fix E2E Infrastructure Preservation)

This issue CANNOT be implemented until Issue #21 is completed because:

1. Manual Testing Required: The destroy CLI command must be manually tested to ensure it works correctly
2. E2E Infrastructure Needed: Manual testing requires preserving E2E infrastructure using --keep flag
3. Verification Workflow: Developers need to:
   • Run E2E tests with --keep to provision infrastructure
   • Test the destroy CLI command on that preserved infrastructure
   • Verify complete cleanup using LXD commands (lxc list | grep e2e-provision)

Without Issue #21 completed, the manual testing workflow is broken and this destroy CLI implementation cannot be properly validated.

🎯 Goals

• Add destroy subcommand to Clap configuration
• Wire up subcommand to call DestroyCommandHandler from application layer
• Implement VerbosityLevel enum and UserOutput struct
• Add essential progress messages using UserOutput
• Ensure separation between user output and internal logging

📦 Scope

Clap Subcommand Structure

Add to src/app.rs:

#[derive(Subcommand)]
pub enum Commands {
    /// Destroy an existing deployment environment
    Destroy {
        /// Name of the environment to destroy
        environment: String,
    },
}

UserOutput Integration

• Add VerbosityLevel enum (Quiet, Normal, Verbose, VeryVerbose, Debug)
• Add UserOutput struct with methods for different message types
• Note: Only enum definition for now, no Clap verbosity flags yet
• Use UserOutput for essential destroy command messages

Example Usage

torrust-tracker-deployer destroy <ENVIRONMENT_NAME>

Example Output (Normal verbosity level)

⏳ Destroying environment 'my-env'...
⏳ Tearing down infrastructure...
⏳ Cleaning up resources...
✅ Environment 'my-env' destroyed successfully

✅ Acceptance Criteria

Prerequisites: Issue #21 (Fix E2E Infrastructure Preservation) must be completed before this can be fully tested and accepted.

• destroy subcommand added to Clap configuration
• Subcommand accepts required environment parameter
• VerbosityLevel enum implemented with 5 levels (Quiet, Normal, Verbose, VeryVerbose, Debug)
• UserOutput struct implemented with dual writers and proper channel separation
• Channel strategy follows console output patterns research (progress to stderr, results to stdout)
• Essential destroy messages implemented using appropriate channels
• Subcommand successfully calls DestroyCommandHandler from application layer
• User-friendly error messages for invalid environment names
• Help text provides clear usage information
• Unit tests implemented with buffer writers for output capture and assertion
• Unit tests verify proper channel separation (stdout vs stderr)
• Unit tests cover CLI argument parsing and error handling
• Manual testing completed using E2E test infrastructure (--keep flag)
• Manual testing verifies complete infrastructure, data, and build cleanup
• User output completely separated from internal logging
• All linting passes successfully
• Integration works end-to-end with existing command handler

Manual Testing Procedure

⚠️ Prerequisite: Issue #21 (Fix E2E Infrastructure Preservation) must be completed first. The --keep flag functionality is required for this testing procedure.

Step 1: Set up test infrastructure using E2E tests

# Run E2E provision and destroy test but keep infrastructure (don't auto-destroy)
cargo run --bin e2e_provision_and_destroy_tests -- --keep

# This creates an environment named "e2e-provision" with infrastructure ready for testing

Step 2: Test the new destroy CLI command

# Test help output
cargo run -- help destroy
cargo run -- destroy --help

# Test basic destroy command with the E2E environment
cargo run -- destroy e2e-provision

# Test invalid environment names
cargo run -- destroy invalid-name!
cargo run -- destroy ""

S...

Fixes #23

---

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[josecelano]

Code Review Update

I've reviewed the generated code and identified several architectural improvements needed. Rather than providing detailed feedback through PR comments, I'll handle the refactoring directly as it's more efficient than iterating through review cycles.

The main areas I'll be addressing:

1. Architecture improvements - Some circular dependencies in the command handler that need restructuring
2. Error handling patterns - Ensuring consistent error handling throughout the CLI layer
3. Code organization - Better separation of concerns between CLI and application layers
4. Testing coverage - Additional edge case coverage for robust CLI behavior

I'll push the improvements directly to maintain momentum on this PR. The core functionality is solid - these are primarily architectural refinements to align with the project's patterns and principles.

[josecelano]

ACK 87ac5f6