Components Overview¶

System Link provides a variety of component types that integrate seamlessly with Home Assistant through MQTT Discovery. Each component type serves a specific purpose in monitoring or controlling your system.

Component Types¶

Sensors ¶

Monitor numeric system metrics that update periodically.

Examples: CPU usage, memory usage, disk space, uptime, battery level

sensors:
  - cpu: {}
  - memory: {}
  - disk: {}

Binary Sensors ¶

Track boolean (on/off) states.

Examples: System online/offline status, locked state

binary_sensors:
  - status: {}

Buttons ¶

Trigger one-time actions when pressed.

Examples: Shutdown, restart, lock screen, custom commands

buttons:
  - shutdown: {}
  - lock: {}
  - custom:
      name: "Run Backup"
      command: "/scripts/backup.sh"

Switches ¶

Toggle persistent states on and off.

Examples: Startup programs, scheduled cron jobs

switches:
  - startup: {}
  - cron:
      name: "Daily Backup"
      schedule: "0 2 * * *"
      command: "/scripts/backup.sh"

Locks ¶

Control state machines with lock/unlock commands.

Examples: Start/stop applications, complex state management

locks:
  - custom:
      name: "Media Player"
      lock:
        command: "vlc /path/to/video.mp4"
      unlock:
        command: "pkill vlc"

Images ¶

Capture and stream images from your system.

Examples: Screenshots, webcam feeds

images:
  - screen: {}

Updaters ¶

Enable remote updating of System Link itself.

Examples: Self-update capability through Home Assistant

updaters:
  - update: {}

Common Configuration Options¶

All components share some common configuration options:

component_type:
  - name: "Custom Display Name"
    unique_id: "custom_unique_id"
    icon: "mdi:icon-name"
    availability: true

Option	Type	Description	Default
`name`	string	Display name in Home Assistant	Component-specific
`unique_id`	string	Unique identifier for the entity	Auto-generated
`icon`	string	Material Design Icon name	Component-specific
`availability`	boolean	Track and report availability	`true`

Component Categories¶

Monitoring Components¶

Components that observe and report system state:

Sensors - Numeric measurements
Binary Sensors - Boolean states
Images - Visual information

Control Components¶

Components that trigger actions or change system state:

Buttons - One-time actions
Switches - Persistent toggles
Locks - Stateful controls

Management Components¶

Components for system management:

Updaters - Self-update capability

Selective Component Enablement¶

One of System Link's key features is the ability to enable only the components you need. This:

Reduces MQTT traffic
Minimizes attack surface
Keeps Home Assistant entity list clean
Improves performance

Example: Only monitoring, no control

sensors:
  - cpu: {}
  - memory: {}
  - disk: {}

binary_sensors:
  - status: {}

# No buttons, switches, or locks

Custom Components¶

Many component types support custom variants where you can define your own commands:

Custom Button¶

buttons:
  - custom:
      name: "Restart Service"
      icon: mdi:restart
      unique_id: restart_nginx
      command: "systemctl restart nginx"

Custom Sensor¶

sensors:
  - custom:
      name: "Service Status"
      unique_id: nginx_status
      command: "systemctl is-active nginx"
      value_template: "{{ value }}"

Custom Switch (Cron)¶

switches:
  - cron:
      name: "Hourly Health Check"
      schedule: "0 * * * *"
      command: "/scripts/health-check.sh"

Availability Tracking¶

Most components report their availability status to Home Assistant. If System Link disconnects, entities will show as "unavailable".

Disable availability tracking for specific components:

images:
  - screen:
      availability: false  # Don't track availability