plugins/

s9s Plugin System

Overview

The s9s plugin system allows extending the functionality of s9s through modular plugins. Plugins can provide new views, overlay data on existing views, provide data to other plugins, and more.

Plugin Architecture

Core Components

1. Plugin Interface (internal/plugin/interface.go)

   • Base Plugin interface that all plugins must implement
   • Specialized interfaces for different plugin types:
     • ViewPlugin - Provides custom views
     • OverlayPlugin - Overlays data on existing views
     • DataPlugin - Provides data to other plugins
     • ConfigurablePlugin - Runtime configuration support
     • HookablePlugin - Event hooks

2. Plugin Manager (internal/plugin/manager.go)

   • Manages plugin lifecycle (init, start, stop)
   • Handles plugin dependencies
   • Performs health checks
   • Manages plugin state

3. Plugin Registry (internal/plugin/registry.go)

   • Registers and indexes plugins
   • Resolves dependencies
   • Manages plugin metadata

Creating a Plugin

Basic Plugin Structure

package myplugin

import (
    "context"
    "github.com/jontk/s9s/internal/plugin"
)

type MyPlugin struct {
    // Plugin state
}

func New() *MyPlugin {
    return &MyPlugin{}
}

func (p *MyPlugin) GetInfo() plugin.Info {
    return plugin.Info{
        Name:        "my-plugin",
        Version:     "1.0.0",
        Description: "My awesome plugin",
        Author:      "Your Name",
        License:     "MIT",
        Requires:    []string{}, // Dependencies
        Provides:    []string{"feature1", "feature2"},
    }
}

func (p *MyPlugin) Init(ctx context.Context, config map[string]interface{}) error {
    // Initialize plugin with configuration
    return nil
}

func (p *MyPlugin) Start(ctx context.Context) error {
    // Start plugin services
    return nil
}

func (p *MyPlugin) Stop(ctx context.Context) error {
    // Clean up resources
    return nil
}

func (p *MyPlugin) Health() plugin.HealthStatus {
    return plugin.HealthStatus{
        Healthy: true,
        Status:  "healthy",
        Message: "Plugin is running",
    }
}

View Plugin Example

type MyViewPlugin struct {
    MyPlugin // Embed base plugin
}

func (p *MyViewPlugin) GetViews() []plugin.ViewInfo {
    return []plugin.ViewInfo{
        {
            ID:          "my-view",
            Name:        "My View",
            Description: "Custom view for my data",
            Icon:        "📊",
            Shortcut:    "m",
            Category:    "monitoring",
        },
    }
}

func (p *MyViewPlugin) CreateView(ctx context.Context, viewID string) (plugin.View, error) {
    if viewID == "my-view" {
        return NewMyView(), nil
    }
    return nil, fmt.Errorf("unknown view: %s", viewID)
}

Overlay Plugin Example

type MyOverlayPlugin struct {
    MyPlugin // Embed base plugin
}

func (p *MyOverlayPlugin) GetOverlays() []plugin.OverlayInfo {
    return []plugin.OverlayInfo{
        {
            ID:          "cpu-usage",
            Name:        "CPU Usage",
            Description: "Adds CPU usage to job view",
            TargetViews: []string{"jobs"},
            Priority:    100,
        },
    }
}

func (p *MyOverlayPlugin) CreateOverlay(ctx context.Context, overlayID string) (plugin.Overlay, error) {
    if overlayID == "cpu-usage" {
        return NewCPUOverlay(), nil
    }
    return nil, fmt.Errorf("unknown overlay: %s", overlayID)
}

Plugin Configuration

Plugins can define their configuration schema:

ConfigSchema: map[string]plugin.ConfigField{
    "endpoint": {
        Type:        "string",
        Description: "API endpoint URL",
        Default:     "http://localhost:8080",
        Required:    true,
        Validation:  "^https?://",
    },
    "refresh_rate": {
        Type:        "int",
        Description: "Refresh rate in seconds",
        Default:     30,
        Required:    false,
    },
}

Configuration is passed to the plugin during initialization and can be updated at runtime if the plugin implements ConfigurablePlugin.

Plugin Lifecycle

1. Registration: Plugin is registered with the manager
2. Initialization: Init() is called with configuration
3. Start: Start() is called to begin operations
4. Running: Plugin performs its functions
5. Health Checks: Manager periodically calls Health()
6. Stop: Stop() is called for graceful shutdown

Available Plugins

Observability Plugin

Provides Prometheus integration for real-time metrics monitoring.

Features:

• Real-time CPU, memory, disk, and network metrics
• Job-level resource usage from cgroup-exporter
• Metric overlays on existing views
• Alert monitoring
• Historical data analysis

Configuration:

plugins:
  - name: observability
    enabled: true
    config:
      prometheus:
        endpoint: "http://prometheus:9090"
        timeout: "10s"
        refreshInterval: "30s"
      display:
        showOverlays: true
        enableAlerts: true

Plugin Development Guidelines

1. Error Handling: Always return meaningful errors
2. Context Awareness: Respect context cancellation
3. Resource Management: Clean up resources in Stop()
4. Health Reporting: Provide accurate health status
5. Configuration Validation: Validate config in Init()
6. Logging: Use the debug logger for diagnostics
7. Testing: Write unit tests for your plugin

Testing Plugins

func TestMyPlugin(t *testing.T) {
    plugin := New()
    
    // Test initialization
    err := plugin.Init(context.Background(), map[string]interface{}{
        "endpoint": "http://test:8080",
    })
    if err != nil {
        t.Fatalf("Init failed: %v", err)
    }
    
    // Test start
    err = plugin.Start(context.Background())
    if err != nil {
        t.Fatalf("Start failed: %v", err)
    }
    
    // Test health
    health := plugin.Health()
    if !health.Healthy {
        t.Errorf("Plugin unhealthy: %s", health.Message)
    }
    
    // Test stop
    err = plugin.Stop(context.Background())
    if err != nil {
        t.Fatalf("Stop failed: %v", err)
    }
}

Future Enhancements

• External plugin loading (shared libraries)
• Plugin marketplace/registry
• Plugin sandboxing
• Inter-plugin communication
• Plugin versioning and updates
• Resource limits enforcement