apt-ostree/docs/.old/apt-ostree-daemon-plan/architecture/package-management.md

Package Management Architecture

Overview

This document describes the package management architecture for apt-ostree, covering how packages are installed, uninstalled, and managed within the OSTree system. The design follows the same principles as rpm-ostree but integrates with APT instead of RPM.

Package Management Commands

Core Commands

apt-ostree install <packages>

Installs packages by creating new OSTree layers containing the package files.

Implementation Details:

• Creates a new OSTree commit with package files
• Resolves dependencies using APT
• Downloads packages to temporary storage
• Extracts package contents to new OSTree layer
• Updates package database
• Commits changes atomically

Example:

apt-ostree install vim git

Options:

• --reboot - Reboot after installation
• --preview - Show what would be installed
• --check - Verify package integrity
• --cache-only - Use only cached packages

apt-ostree uninstall <packages>

Removes packages by creating a new OSTree commit without the package files.

Implementation Details:

• Creates new OSTree commit excluding package files
• Updates package database
• Removes package metadata
• Commits changes atomically

Example:

apt-ostree uninstall vim

apt-ostree search <query>

Searches for available packages using APT's search capabilities.

Implementation Details:

• Uses APT's search functionality
• Filters results based on current OSTree deployment
• Shows package availability and versions

Example:

apt-ostree search "web server"

Package Layering Architecture

OSTree Layer Management

Packages are managed through OSTree layers, where each package installation creates a new commit:

Base OSTree Commit
├── System packages (base image)
└── User-installed packages (layers)
    ├── Layer 1: vim, git
    ├── Layer 2: nginx
    └── Layer 3: postgresql

Layer Creation Process

1. Dependency Resolution

   • Use APT to resolve package dependencies
   • Download all required packages
   • Verify package integrity

2. OSTree Commit Preparation

   • Create temporary working directory
   • Extract package contents
   • Apply package scripts and configuration

3. Commit Creation

   • Create new OSTree commit with changes
   • Update package database
   • Link to parent commit

4. Deployment Update

   • Update current deployment pointer
   • Prepare for next boot (if --reboot specified)

APT Integration

Package Sources

apt-ostree integrates with APT's package sources:

• Debian/Ubuntu repositories - Standard package sources
• PPAs - Personal Package Archives
• Custom repositories - Third-party package sources

Package Database

Maintains APT package database within OSTree:

• Package metadata
• Dependency information
• Installation status
• Version history

Dependency Resolution

Uses APT's dependency resolver:

• Automatic dependency installation
• Conflict resolution
• Version compatibility checking
• Repository priority handling

Transaction Management

Atomic Operations

All package operations are atomic:

• Success: Complete installation with new OSTree commit
• Failure: Rollback to previous state
• Partial failure: Not possible - all or nothing

Rollback Support

Failed installations automatically rollback:

• Remove temporary files
• Restore previous OSTree commit
• Clean up package database
• Maintain system consistency

Package Overrides

Override System

Packages can be overridden at different levels:

• System level - Base image packages
• User level - User-installed packages
• Temporary - Runtime overrides

Override Commands

# Replace system package
apt-ostree override replace <package>

# Remove override
apt-ostree override remove <package>

# Reset to default
apt-ostree override reset <package>

Security Considerations

Package Verification

• GPG signature verification
• Package integrity checks
• Repository authenticity validation
• Secure download protocols

Privilege Management

• Polkit-based authorization
• Root privilege requirements
• User permission checking
• Audit logging

Performance Optimization

Caching Strategy

• Package download caching
• OSTree commit caching
• Dependency resolution caching
• Metadata caching

Parallel Operations

• Concurrent package downloads
• Parallel dependency resolution
• Background OSTree operations
• Asynchronous processing

Error Handling

Common Error Scenarios

1. Package Not Found

   • Check repository configuration
   • Verify package names
   • Update package lists

2. Dependency Conflicts

   • Automatic conflict resolution
   • Manual conflict resolution
   • Rollback on unresolvable conflicts

3. Network Issues

   • Retry mechanisms
   • Offline package installation
   • Partial download recovery

4. Disk Space Issues

   • Space requirement checking
   • Automatic cleanup
   • User notification

Integration with rpm-ostree

Command Compatibility

apt-ostree maintains 1:1 CLI compatibility with rpm-ostree:

• Same command names and options
• Identical exit codes
• Compatible error messages
• Similar help output

Feature Parity

Core package management features match rpm-ostree:

• Package installation/uninstallation
• Dependency resolution
• OSTree layering
• Transaction management
• Rollback support

Future Enhancements

Planned Features

1. Package Groups

   • Install package collections
   • Group-based management
   • Dependency optimization

2. Advanced Caching

   • Intelligent cache management
   • Predictive downloads
   • Bandwidth optimization

3. Package Pinning

   • Version pinning
   • Repository pinning
   • Update control

4. Rollback History

   • Extended rollback support
   • Rollback metadata
   • Rollback scheduling

Implementation Notes

Current Status

• Basic package management implemented
• APT integration functional
• OSTree layering working
• Transaction system operational

Next Steps

1. Performance Optimization

   • Implement caching strategies
   • Optimize OSTree operations
   • Improve dependency resolution

2. Advanced Features

   • Package groups support
   • Advanced override system
   • Enhanced rollback capabilities

3. Testing and Validation

   • Comprehensive testing
   • Performance benchmarking
   • Security auditing