- Create detailed implementation plan for Phase 3: Maximum Practical Application Installation Automation
- Document current state analysis with accurate status of implemented vs missing components
- Provide technical implementation details for SSL certificate automation and MySQL backup automation
- Include testing strategy with unit, integration, SSL workflow, and end-to-end testing approaches
- Define success criteria focusing on 90%+ automation with minimal manual steps
- Add risk assessment and mitigation strategies for high-risk areas
- Establish timeline and dependencies for SSL automation (Week 1) and MySQL backup automation (Week 1-2)
- Document extension points for existing twelve-factor deployment workflow
- Include comprehensive crontab template integration and cloud-init automation
- Provide detailed technical specifications for supporting scripts and environment template updates

Critical Review Findings:
- Updated status table to reflect actual repository state (40% complete, 4/12 components)
- Identified missing files: mysql-backup.sh, crontab_utils.sh
- Clarified nginx template state (HTTP active, HTTPS commented out)
- Corrected environment template status (SSL/backup variables already present)
- Fixed all markdown linting issues and improved documentation structure

This plan provides the foundation for implementing maximum practical automation while maintaining
the existing robust twelve-factor deployment architecture.

- Add comprehensive validation for SSL and backup variables in configure-env.sh
- Validate DOMAIN_NAME, CERTBOT_EMAIL (with email format check), ENABLE_SSL
- Validate ENABLE_DB_BACKUPS and BACKUP_RETENTION_DAYS (with range checks)
- Extend placeholder detection for both REPLACE_WITH_SECURE_* and REPLACE_WITH_YOUR_* patterns
- Update ADR-004 to document deployment automation configuration exception
- Update environment template comments to clarify variable purposes
- All e2e tests pass, validates 50% completion of issue #21

This implements Task 1.2 of the automation roadmap, providing foundation
for SSL certificate and backup automation scripts.

…nfiguration

- Replace dual templates (local.env.tpl, production.env.tpl) with single base.env.tpl
- Add external defaults files (local.defaults, production.defaults) for environment-specific values
- Update configure-env.sh to load defaults from files instead of hardcoded values
- Improve twelve-factor compliance with single source of truth for configuration
- Add generate-secrets command for secure production secret generation
- Update documentation and .gitignore for new file structure
- Benefits: DRY principle, easier maintenance, version-controlled defaults, no sync issues

This addresses the issue where having separate templates could lead to
synchronization bugs when adding new variables to only one template.
All environment variables now exist in one place with environment-specific
values defined in external, version-controlled defaults files.

## Database Backup Automation - FULLY COMPLETED

### ✅ Core Implementation
- **mysql-backup.sh**: Comprehensive MySQL backup script with compression, retention, logging
- **deploy-app.sh**: Integrated backup automation via setup_backup_automation() in run_stage()
- **Environment templates**: Added ENABLE_DB_BACKUPS and BACKUP_RETENTION_DAYS variables
- **Cron automation**: Automated backup scheduling integrated into deployment workflow

### ✅ Key Features Implemented
- Single-transaction MySQL dumps for data consistency
- Automatic gzip compression to save storage space
- Configurable retention policy (BACKUP_RETENTION_DAYS environment variable)
- Comprehensive error handling and logging for monitoring
- Docker Compose environment integration
- Conditional deployment based on ENABLE_DB_BACKUPS flag

### ✅ Testing & Validation
- Manual end-to-end testing with backup content verification
- Automated scheduling tested with cron job modification
- Log output validation and error handling verification
- Created comprehensive manual testing guide

### ✅ Documentation
- **database-backup-testing-guide.md**: Complete manual testing procedures
- **21-complete-application-installation-automation.md**: Updated status to reflect completion
- Progress updated from 67% to 83% (10/12 components complete)
- Phase 3 marked as fully completed with testing documentation

### 🎯 Production Ready
- Backup automation is fully functional and production-ready
- Zero manual configuration required when ENABLE_DB_BACKUPS=true
- Integrates seamlessly with existing twelve-factor deployment workflow
- All CI tests pass, shellcheck clean, comprehensive error handling

**Next Phase**: SSL certificate automation (manual scripts for admins)