Shipping Operating System Components as Snaps: Technical Deep Dive
System Architecture and Implementation
- Snap Package Structure
snap/
├── meta/
│ ├── snap.yaml # Package metadata
│ └── hooks/ # Installation/removal hooks
├── usr/ # Application files
├── lib/ # Libraries
└── snapcraft.yaml # Build configuration
- Core Components Integration
# Example snapcraft.yaml for system component
name: system-component
version: '1.0'
summary: Critical system component
grade: stable
confinement: strict
parts:
component:
plugin: autotools
source: https://example.com/component.tar.gz
stage-packages:
- required-lib1
- required-lib2
build-packages:
- build-essential
Interfaces and Security Confinement
- System Interfaces
slots:
system-files:
interface: system-files
read:
- /sys/devices
- /proc/sys
write:
- /proc/sys/kernel
- Security Policies
AppArmor profiles for system components
Seccomp filters for system calls
Interface connections for inter-component communication
Resource Management
- Snap Confinement Levels
# Available confinement modes
strict # Full confinement
classic # Unrestricted access
devmode # Development mode with logging
- Resource Controls
# Resource limitations in snap config
apps:
daemon:
daemon: simple
restart-condition: always
memory-limit: 512MB
cpu-quota: 50%
Update Management and Rollback
- Transaction Management
# Snapshot before update
snap save system-component
# Perform update
snap refresh system-component
# Rollback if needed
snap revert system-component
- Update Control
refresh-control:
refresh-schedule: 02:00-04:00
hold: [system-component]
defer: 7
Integration with System Services
- Systemd Integration
[Unit]
Description=System Component Service
After=snapd.service
[Service]
ExecStart=/snap/bin/system-component
Restart=always
Type=simple
[Install]
WantedBy=multi-user.target
- Service Management
# Service operations
snap start system-component
snap stop system-component
snap restart system-component
Performance Considerations
- Mount Points and Storage
# Typical mount structure
/snap/system-component/current/
/var/snap/system-component/common/
/var/snap/system-component/current/
- Cache Management
# Cache cleanup
snap set system refresh.retain=2
snap clean
Monitoring and Debugging
- Logging Configuration
apps:
daemon:
command: bin/daemon
daemon: simple
plugs: [log-observe]
- Debug Information
# Debug commands
snap run --shell system-component
snap run --strace=system-component
journalctl -u snap.system-component
Comparison with Flatpak (Technical Aspects)
- Package Structure
# Snap
/snap/bin/
/snap/core/
/var/snap/
# Flatpak
/var/lib/flatpak/
/usr/share/flatpak/
- Runtime Differences
# Snap base
core18, core20, core22
# Flatpak runtimes
org.freedesktop.Platform//21.08
Implementation Example
name: system-daemon
version: '2.0'
summary: Critical system daemon
grade: stable
base: core22
confinement: strict
apps:
daemon:
command: bin/daemon
daemon: simple
plugs:
- network
- system-observe
slots:
- service-control
parts:
daemon:
plugin: cmake
source: https://github.com/org/daemon.git
build-packages:
- build-essential
- libsystemd-dev
stage-packages:
- libsystemd0
override-build: |
cmake .
make
make install DESTDIR=$SNAPCRAFT_PART_INSTALL
Performance Optimization
- Cache Configuration
environment:
SNAP_CACHE_DIR: $SNAP_COMMON/cache
LD_LIBRARY_PATH: $SNAP/usr/lib:$LD_LIBRARY_PATH
- Memory Management
# Memory limits in systemd unit
MemoryLimit=1G
MemorySwapMax=0
This technical approach focuses on implementation details, configuration examples, and system integration aspects. The examples demonstrate real-world usage patterns and configuration options for system administrators and developers working with snap-based OS components.