Comprehensive improvements: pigz support, error handling, documentation, and interactive configuration

[rogerb831]

Overview

This PR includes comprehensive improvements to the Coolify migration script, building upon the community contributions and adding significant enhancements for robustness, usability, and documentation.

Key Features

🚀 Pigz Support (includes Cristy94's PR #9)

• Early detection and auto-installation: The script now detects pigz at startup and offers to auto-install it if missing
• OS-aware installation: Automatically detects the OS and uses the appropriate package manager (apt, yum, dnf, zypper, pacman, apk)
• Parallel compression/decompression: Uses pigz for faster backups when available, with graceful fallback to gzip
• Note: This includes and extends the pigz support from Cristy94's PR #9, adding auto-installation capabilities and early detection

⚙️ Interactive Configuration

• Prompts for SSH key path and destination host if defaults are still set
• Allows users to either edit the script directly or be prompted at runtime
• Validates all inputs before proceeding

🛡️ Comprehensive Error Handling

• Validates Docker installation and running state
• Handles container inspection failures gracefully
• Checks for empty volume paths before processing
• Improved error messages with actionable guidance
• Better handling of edge cases (missing files, permissions, etc.)

📚 Complete Documentation

• Comprehensive README.md with:
  • Detailed overview and features
  • Prerequisites and installation instructions
  • Configuration options and usage guide
  • Troubleshooting section for common issues
  • Safety considerations and best practices
  • Supported operating systems documentation

🔧 Code Quality Improvements

• Fixed variable quoting issues to prevent word splitting
• Added proper error handling for SSH key operations
• Improved OS detection patterns for consistency
• Added fallback for nproc command
• Better handling of systemctl availability
• Fixed syntax and indentation issues

Changes Summary

• migrate.sh: 278 lines changed (significant improvements)
• README.md: 325 lines added (comprehensive documentation)

Testing

The script has been tested with:

• Various Linux distributions (Debian, Ubuntu, CentOS, etc.)
• Different Docker volume configurations
• Both with and without pigz installed
• Edge cases (missing files, permissions, etc.)

Related PRs

• Includes and extends pigz support from Cristy94's PR #9
• Builds upon community contributions from the fork ecosystem

Benefits

1. Better User Experience: Interactive prompts make it easier for first-time users
2. Faster Backups: Auto-installation of pigz enables parallel compression
3. More Reliable: Comprehensive error handling prevents silent failures
4. Better Documented: Complete documentation helps users understand and troubleshoot
5. More Robust: Handles edge cases and different system configurations

This PR consolidates improvements from the community while maintaining backward compatibility and improving the overall quality of the migration script.