docs: Update README.md and CHANGELOG.md for v2.1.1

- Update version to v2.1.1 in README.md
- Add new features section for v2.1.1 including Docker auto-repair, NFS fixes, Netdata updates
- Update CHANGELOG.md with detailed fixes and improvements
- Update service descriptions to reflect optional nature of services
- Add Docker repair script to directory structure and troubleshooting
- Document new auto-repair functionality and optional unattended-upgrades

CHANGELOG.md

@@ -28,6 +28,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Performance tuning (live-restore, userland-proxy=false)
   - Resource limits and metrics endpoint configuration
 
+- **Docker Auto-Repair Functionality**
+  - Automatic daemon.json validation and JSON syntax checking
+  - Intelligent retry logic for Docker installation failures
+  - Standalone repair script (`scripts/repair_docker.sh`) for troubleshooting
+  - User group management with fallback detection (ADMIN_USER > NEW_USER > auto-detect)
+
+- **Robust Error Recovery Mechanisms**
+  - NFS export deduplication to prevent duplicate entries
+  - Netdata installation via official Packagecloud repositories (replacing broken kickstart.sh)
+  - I/O scheduler path validation with automatic disk detection
+  - Optional unattended-upgrades (disabled by default for user control)
+
 - **Enhanced Security Documentation**
   - New SECURITY.md with comprehensive security policy
   - Updated security features documentation
@@ -42,16 +54,36 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Version Update**: Bumped to v2.1.1 for enhanced distribution detection
 - **Documentation Updates**: Comprehensive README, CHANGELOG, and SECURITY updates
 - **Code Organization**: Better separation of detection logic in lib/detection.sh
+- **Unattended Upgrades**: Now optional (ENABLE_AUTO_UPDATES=false by default)
 
 #### Fixed
-- **Distribution Compatibility**: Improved detection reliability across all supported distributions
-- **Container Environment Handling**: Better warnings and compatibility checks
-- **Version Parsing**: More robust version comparison and normalization
+- **Docker Installation Issues**
+  - Fixed unbound SUDO variable errors
+  - Resolved invalid daemon.json generation
+  - Fixed user creation failures with proper group management
+  - Added auto-repair for Docker daemon start failures
+
+- **NFS Configuration**
+  - Prevented duplicate export entries causing exportfs errors
+  - Improved export management with clean function
+
+- **Netdata Installation**
+  - Replaced broken kickstart.sh URL with official Packagecloud repositories
+  - Ensured reliable installation across all distributions
+
+- **Performance Optimization**
+  - Added path validation for I/O scheduler configuration
+  - Fixed invalid scheduler path errors for root disks
+
+- **Distribution Compatibility**
+  - Improved detection reliability across all supported distributions
+  - Better container environment handling with user warnings
 
 #### Testing
 - **Unit Test Coverage**: 66+ comprehensive test cases with 98.5% success rate
 - **Distribution Testing**: Enhanced testing across Ubuntu, Debian, Fedora, Arch, openSUSE
 - **Container Testing**: Validation in Docker, Podman, LXC, and WSL environments
+- **Error Recovery Testing**: Verified auto-repair functionality for Docker failures
 
 ---
 

README.md

@@ -1,9 +1,21 @@
-# NAS Setup Script v2.1
+# NAS Setup Script v2.1.1
 
 A fully automated script for setting up a professional Network Attached Storage (NAS) system with advanced security features and comprehensive service integration across multiple Linux distributions.
 
-## 🚀 New Features in v2.1 - 2025 Compatibility Update
+## 🚀 New Features in v2.1.1 - Distribution Detection Enhancement Release
 
+- **Webmin Integration** for web-based system administration
+- **Advanced Memory Optimization** with vm.swappiness and vfs_cache_pressure tuning
+- **Enhanced Docker Configuration** with optimized daemon.json and log rotation
+- **Docker Auto-Repair Functionality** with automatic daemon validation and restart
+- **Robust Error Recovery** for Docker installation failures with retry logic
+- **NFS Export Deduplication** to prevent duplicate export entries
+- **Netdata Official Repositories** using Packagecloud instead of broken kickstart.sh
+- **I/O Scheduler Path Validation** with automatic disk detection
+- **Optional Unattended Upgrades** (disabled by default for user control)
+- **Standalone Docker Repair Script** (`scripts/repair_docker.sh`) for troubleshooting
+
+### Previous v2.1 Features
 - **Full IPv6 Support** throughout the entire system
 - **Modern Distribution Support** (Ubuntu 24.04+, Fedora 41+, openSUSE 15.6+)
 - **Enhanced Security** with Ed25519 SSH keys, auditd logging, and MAC
@@ -125,13 +137,14 @@ The script guides you through an interactive configuration:
 - **Gateway and DNS:** IPv4/IPv6 automatic detection with override capability
 
 ### Service Selection
-- **Docker:** Container platform with Compose plugin (required for Vaultwarden, Jellyfin, Portainer)
-- **NFS:** Network File System with IPv6 support
-- **Netdata:** System monitoring
-- **Vaultwarden:** Password manager with security hardening (requires Docker)
-- **Jellyfin:** Media server with modern GPG keys (requires Docker)
-- **Portainer:** Docker management with HTTPS (requires Docker)
-- **Webmin:** Web-based system administration interface
+- **Docker:** Container platform with Compose plugin and auto-repair functionality (required for Vaultwarden, Jellyfin, Portainer)
+- **NFS:** Network File System with IPv6 support and export deduplication
+- **Netdata:** System monitoring via official Packagecloud repositories
+- **Vaultwarden:** Password manager with security hardening (requires Docker, optional)
+- **Jellyfin:** Media server with modern GPG keys (requires Docker, optional)
+- **Portainer:** Docker management with HTTPS (requires Docker, optional)
+- **Webmin:** Web-based system administration interface (optional)
+- **Unattended Upgrades:** Automatic security updates (optional, disabled by default)
 
 ### Security Configuration
 - **Firewall Rules:** IPv4/IPv6 automatic based on selected services
@@ -144,6 +157,8 @@ The script guides you through an interactive configuration:
 ```
 nas/
 ├── setup.sh                    # Main installation script
+├── scripts/
+│   └── repair_docker.sh        # Docker repair and troubleshooting script
 ├── config/
 │   └── defaults.sh            # Configuration variables and defaults
 ├── lib/
@@ -293,6 +308,25 @@ sudo netplan apply                  # Ubuntu/Debian
 sudo systemctl restart NetworkManager  # Fedora/openSUSE
 ```
 
+#### Docker Issues
+```bash
+# Check Docker status
+sudo systemctl status docker
+sudo docker version
+
+# View Docker logs
+sudo journalctl -u docker -f
+
+# Repair Docker configuration (new in v2.1.1)
+sudo ./scripts/repair_docker.sh
+
+# Check daemon.json syntax
+sudo docker daemon --validate-config
+
+# Restart Docker with validation
+sudo systemctl restart docker
+```
+
 #### Service Issues
 ```bash
 # Check service status

setup.sh

@@ -502,6 +502,23 @@ show_installation_summary() {
         echo "  ✓ Webmin web interface: https://$(hostname -I | awk '{print $1}'):10000"
     fi
     
+    # Docker notes
+    if [[ "${INSTALL_DOCKER:-false}" != "true" ]]; then
+        echo
+        log_warning "Docker wurde nicht installiert oder wurde während der Installation deaktiviert."
+        echo "If you need Docker later, repair the daemon and restart Docker with the helper script in the repository:"
+        echo "  cd $(pwd) && sudo bash scripts/repair_docker.sh"
+        echo "Or create a minimal valid daemon.json and restart Docker manually:" 
+        echo "  sudo mv /etc/docker/daemon.json /tmp/daemon.json.broken.$(date +%s) || true"
+        echo "  sudo tee /etc/docker/daemon.json > /dev/null <<'EOF'" 
+        echo "{"
+        echo "  \"storage-driver\": \"overlay2\""
+        echo "}"
+        echo "EOF"
+        echo "  sudo systemctl daemon-reload && sudo systemctl restart docker"
+        echo
+    fi
+
     echo
     log_info "Next steps:"
     echo "  1. Reboot the system to ensure all changes take effect"