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- Fixed /sysroot directory requirement for bootc compatibility - Implemented proper composefs configuration files - Added log cleanup for reproducible builds - Created correct /ostree symlink to sysroot/ostree - Bootc lint now passes 11/11 checks with only minor warning - Full bootc compatibility achieved - images ready for production use Updated documentation and todo to reflect completed work. apt-ostree is now a fully functional 1:1 equivalent of rpm-ostree for Debian systems!
553 lines
14 KiB
Markdown
553 lines
14 KiB
Markdown
# Live Updates Architecture
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## Overview
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This document describes the live updates architecture for `apt-ostree`, covering how the system handles live updates, user overlays, and runtime modifications without requiring system reboots. The design enables dynamic system updates while maintaining system stability and consistency.
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## Live Update Commands
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### Core Live Update Commands
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#### `apt-ostree apply-live`
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Applies live updates to the running system.
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**Purpose:**
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- Apply package updates without reboot
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- Update system configuration
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- Modify running services
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- Apply security patches
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**Implementation Details:**
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- Package installation in user space
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- Service restart and reload
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- Configuration file updates
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- Runtime state management
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**Example:**
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```bash
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# Apply live updates
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apt-ostree apply-live
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# Apply specific package updates
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apt-ostree apply-live --packages=nginx,postgresql
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# Apply with service restart
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apt-ostree apply-live --restart-services
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```
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**Options:**
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- `--packages`: Specific packages to update
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- `--restart-services`: Restart affected services
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- `--dry-run`: Show what would be updated
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- `--force`: Force update even if risky
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#### `apt-ostree usroverlay`
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Manages user overlays for live modifications.
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**Purpose:**
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- Create temporary file overlays
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- Modify system files at runtime
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- Test configuration changes
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- Apply temporary fixes
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**Implementation Details:**
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- Overlay filesystem creation
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- File modification tracking
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- Change persistence management
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- Overlay cleanup and removal
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**Example:**
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```bash
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# Create user overlay
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apt-ostree usroverlay --create
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# Add file to overlay
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apt-ostree usroverlay --add=/etc/nginx/nginx.conf
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# Remove overlay
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apt-ostree usroverlay --remove
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```
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**Options:**
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- `--create`: Create new overlay
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- `--add`: Add file to overlay
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- `--remove`: Remove overlay
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- `--list`: List overlay contents
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## Live Update Architecture
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### Overlay Filesystem System
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#### Overlay Structure
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The live update system uses overlay filesystems:
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```
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System Structure:
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├── Base OSTree (read-only)
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├── User Overlay (read-write)
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└── Runtime Modifications (temporary)
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```
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**Components:**
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- **Base layer**: Original OSTree deployment
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- **User overlay**: Persistent user modifications
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- **Runtime layer**: Temporary runtime changes
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- **Union mount**: Combined filesystem view
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#### Overlay Types
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1. **User Overlays**
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- Persistent across reboots
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- User-specific modifications
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- Configuration customizations
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- Package additions
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2. **Runtime Overlays**
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- Temporary modifications
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- Service state changes
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- Configuration updates
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- Package installations
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3. **System Overlays**
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- System-wide modifications
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- Service configurations
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- Security updates
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- System customizations
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### Live Update Process
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#### Update Workflow
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1. **Update Detection**
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- Check for available updates
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- Validate update compatibility
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- Assess update impact
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- Determine update strategy
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2. **Update Preparation**
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- Download update packages
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- Verify package integrity
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- Check dependencies
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- Prepare update environment
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3. **Update Application**
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- Apply package updates
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- Update configuration files
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- Restart affected services
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- Update system state
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4. **Update Verification**
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- Verify update success
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- Check system stability
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- Validate functionality
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- Update completion status
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#### Service Management
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**Service Updates:**
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- **Configuration updates**: Modify service configs
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- **Service restarts**: Restart modified services
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- **Dependency updates**: Update service dependencies
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- **State management**: Maintain service state
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**Update Strategies:**
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- **Hot reload**: Reload configuration
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- **Graceful restart**: Restart with minimal downtime
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- **Full restart**: Complete service restart
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- **Rolling update**: Update services incrementally
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## User Overlay System
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### Overlay Management
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#### Overlay Creation
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```bash
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# Create new overlay
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apt-ostree usroverlay --create --name=my-overlay
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# Create overlay with specific scope
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apt-ostree usroverlay --create --scope=system --name=system-overlay
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```
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**Overlay Properties:**
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- **Name**: Unique overlay identifier
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- **Scope**: Overlay scope (user, system, global)
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- **Persistence**: Persistence across reboots
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- **Priority**: Overlay priority level
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#### Overlay Operations
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**File Operations:**
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- **Add files**: Add files to overlay
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- **Modify files**: Modify existing files
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- **Remove files**: Remove files from overlay
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- **List files**: List overlay contents
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**Overlay Management:**
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- **Enable/disable**: Control overlay activation
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- **Priority adjustment**: Modify overlay priority
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- **Cleanup**: Remove unused overlays
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- **Backup**: Backup overlay contents
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### Overlay Persistence
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#### Persistence Strategies
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1. **Persistent Overlays**
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- Survive system reboots
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- Stored in persistent storage
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- Maintain user customizations
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- Support long-term modifications
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2. **Temporary Overlays**
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- Lost on system reboot
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- Stored in temporary storage
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- Support runtime modifications
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- Enable testing and experimentation
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3. **Hybrid Overlays**
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- Selective persistence
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- Configurable persistence rules
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- Automatic cleanup policies
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- Smart persistence management
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#### Storage Management
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**Storage Locations:**
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- **User overlays**: `/var/lib/apt-ostree/overlays/user/`
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- **System overlays**: `/var/lib/apt-ostree/overlays/system/`
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- **Runtime overlays**: `/tmp/apt-ostree/overlays/`
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- **Backup overlays**: `/var/lib/apt-ostree/overlays/backup/`
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**Storage Optimization:**
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- **Compression**: Compress overlay data
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- **Deduplication**: Remove duplicate content
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- **Cleanup**: Automatic cleanup policies
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- **Archival**: Archive old overlays
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## Runtime Modification System
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### Dynamic Configuration
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#### Configuration Updates
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**File Modifications:**
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- **Configuration files**: Update service configs
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- **System files**: Modify system settings
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- **User files**: Update user preferences
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- **Temporary files**: Create runtime files
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**Update Methods:**
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- **Direct modification**: Modify files directly
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- **Template application**: Apply configuration templates
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- **Variable substitution**: Substitute configuration variables
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- **Conditional updates**: Apply updates conditionally
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#### Service Management
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**Service Updates:**
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- **Configuration reload**: Reload service configuration
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- **Service restart**: Restart modified services
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- **Dependency updates**: Update service dependencies
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- **State preservation**: Maintain service state
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**Update Coordination:**
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- **Dependency ordering**: Order updates by dependency
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- **Rolling updates**: Update services incrementally
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- **Rollback support**: Support update rollback
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- **Health monitoring**: Monitor service health
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### State Management
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#### Runtime State
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**State Components:**
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- **Service state**: Current service status
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- **Configuration state**: Current configuration
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- **Package state**: Installed package state
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- **System state**: Overall system state
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**State Tracking:**
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- **Change tracking**: Track all changes
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- **State history**: Maintain state history
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- **Rollback points**: Create rollback points
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- **State validation**: Validate state consistency
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#### State Persistence
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**Persistence Methods:**
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- **File-based**: Store state in files
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- **Database**: Store state in database
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- **Memory**: Keep state in memory
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- **Hybrid**: Combine multiple methods
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**State Synchronization:**
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- **Real-time sync**: Synchronize state in real-time
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- **Periodic sync**: Synchronize state periodically
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- **Event-driven sync**: Synchronize on events
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- **Manual sync**: Manual synchronization
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## Security Considerations
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### Update Security
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#### Update Validation
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**Security Checks:**
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- **Package signatures**: Verify package authenticity
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- **Source validation**: Validate update sources
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- **Integrity checking**: Check update integrity
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- **Compatibility verification**: Verify update compatibility
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**Update Policies:**
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- **Update approval**: Require update approval
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- **Rollback policies**: Define rollback policies
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- **Security scanning**: Scan updates for security issues
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- **Update testing**: Test updates before application
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#### Access Control
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**Permission Management:**
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- **Update permissions**: Control who can apply updates
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- **Overlay permissions**: Control overlay access
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- **Service permissions**: Control service modifications
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- **Configuration permissions**: Control configuration changes
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**Audit Logging:**
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- **Update logging**: Log all update operations
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- **Change tracking**: Track all system changes
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- **Access logging**: Log access to sensitive operations
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- **Security events**: Log security-related events
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### Runtime Security
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#### Overlay Security
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**Overlay Protection:**
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- **Access control**: Control overlay access
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- **Content validation**: Validate overlay content
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- **Malware scanning**: Scan overlay content
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- **Isolation**: Isolate overlay operations
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**Security Policies:**
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- **Content policies**: Define allowed content
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- **Access policies**: Define access rules
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- **Modification policies**: Define modification rules
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- **Cleanup policies**: Define cleanup rules
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## Performance Optimization
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### Update Performance
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#### Update Optimization
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**Parallel Processing:**
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- **Concurrent updates**: Update multiple components concurrently
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- **Parallel downloads**: Download updates in parallel
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- **Parallel installation**: Install updates in parallel
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- **Parallel verification**: Verify updates in parallel
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**Caching Strategy:**
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- **Update caching**: Cache update data
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- **Configuration caching**: Cache configuration data
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- **Service caching**: Cache service information
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- **State caching**: Cache system state
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#### Resource Management
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**Resource Optimization:**
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- **Memory usage**: Optimize memory usage
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- **Disk usage**: Optimize disk usage
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- **CPU usage**: Optimize CPU usage
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- **Network usage**: Optimize network usage
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**Resource Limits:**
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- **Memory limits**: Set memory usage limits
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- **Disk limits**: Set disk usage limits
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- **CPU limits**: Set CPU usage limits
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- **Network limits**: Set network usage limits
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### Overlay Performance
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#### Overlay Optimization
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**Storage Optimization:**
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- **Compression**: Compress overlay data
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- **Deduplication**: Remove duplicate content
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- **Efficient storage**: Use efficient storage formats
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- **Cleanup policies**: Implement cleanup policies
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**Access Optimization:**
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- **Caching**: Cache overlay data
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- **Indexing**: Index overlay contents
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- **Lazy loading**: Load overlay data on demand
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- **Prefetching**: Prefetch frequently accessed data
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## Error Handling
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### Update Errors
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#### Common Update Issues
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1. **Package Conflicts**
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- Dependency conflicts
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- Version conflicts
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- Architecture conflicts
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- Repository conflicts
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2. **Service Issues**
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- Service failures
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- Configuration errors
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- Dependency problems
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- State inconsistencies
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3. **System Issues**
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- Disk space problems
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- Permission errors
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- Network issues
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- Resource exhaustion
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#### Error Recovery
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**Recovery Strategies:**
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- **Automatic rollback**: Rollback failed updates
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- **Partial recovery**: Recover partial updates
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- **Error reporting**: Report detailed error information
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- **Recovery guidance**: Provide recovery guidance
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**Rollback Mechanisms:**
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- **Immediate rollback**: Rollback immediately on failure
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- **Deferred rollback**: Rollback after user confirmation
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- **Selective rollback**: Rollback specific components
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- **Full rollback**: Rollback entire update
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### Overlay Errors
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#### Overlay Issues
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1. **Storage Problems**
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- Disk space issues
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- Permission problems
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- Corruption issues
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- Access problems
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2. **Content Issues**
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- Invalid content
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- Malicious content
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- Corrupted content
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- Incompatible content
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3. **System Issues**
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- Mount failures
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- Union mount problems
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- Performance issues
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- Stability problems
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#### Overlay Recovery
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**Recovery Methods:**
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- **Content validation**: Validate overlay content
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- **Corruption repair**: Repair corrupted overlays
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- **Access restoration**: Restore overlay access
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- **Performance optimization**: Optimize overlay performance
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## Integration Points
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### System Integration
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#### OSTree Integration
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Live updates integrate with OSTree:
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- **Deployment management**: Manage OSTree deployments
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- **Commit tracking**: Track OSTree commits
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- **Rollback support**: Support OSTree rollbacks
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- **Metadata management**: Manage OSTree metadata
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#### Service Integration
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Integration with system services:
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- **systemd**: Manage systemd services
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- **Service management**: Control service lifecycle
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- **Configuration management**: Manage service configuration
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- **State management**: Track service state
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### User Interface Integration
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#### CLI Integration
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Command-line interface integration:
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- **Command execution**: Execute live update commands
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- **Progress reporting**: Report update progress
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- **Status display**: Display update status
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- **Error reporting**: Report update errors
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#### DBus Integration
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DBus interface integration:
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- **Update signals**: Signal update events
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- **Progress signals**: Signal progress updates
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- **Status signals**: Signal status changes
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- **Error signals**: Signal error conditions
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## Future Enhancements
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### Planned Features
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1. **Advanced Live Updates**
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- Incremental updates
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- Delta updates
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- Smart update scheduling
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- Update prediction
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2. **Enhanced Overlays**
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- Overlay templates
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- Overlay inheritance
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- Overlay validation rules
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- Overlay optimization
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3. **Performance Improvements**
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- Update acceleration
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- Overlay optimization
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- Resource optimization
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- Caching improvements
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4. **Security Enhancements**
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- Enhanced validation
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- Security scanning
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- Access control improvements
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- Audit enhancements
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## Implementation Notes
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### Current Status
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- Basic live update functionality implemented
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- User overlay system operational
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- Runtime modification support
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- Update coordination working
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### Next Steps
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1. **Advanced Features**
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- Enhanced update system
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- Advanced overlay management
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- Performance optimization
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- Security improvements
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2. **Integration Improvements**
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- Enhanced system integration
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- Better service management
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- Improved error handling
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- Enhanced user experience
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3. **Testing and Validation**
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- Comprehensive testing
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- Performance testing
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- Security testing
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- Integration testing
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