Governance Library

A Go library for service discovery and management in microservices architectures. This library provides a centralized governance manager that tracks service registrations, performs health checks, and notifies subscribers of service changes.

Features

• Service Registration: Services register themselves with protocol endpoints (HTTP, TCP, PFCP, GTP, UDP)
• Subscription System: Services can subscribe to other service groups for change notifications
• Health Checking: Automatic periodic health checks with retry mechanism
• Event-Driven Architecture: Uses go-event-queue for lock-free event processing
• Automatic Notifications: Subscribers are notified when services register, unregister, or change health status
• Periodic Reconciliation: Regular full-state notifications to all subscribers

Architecture

The library consists of two main components:

Manager

The centralized governance service that:

• Exposes REST API for service registration/unregistration
• Maintains in-memory registry of all services
• Performs periodic health checks on registered services
• Processes events through a single-worker event queue (FIFO)
• Sends notifications to subscribers when changes occur

Client

Helper library for services to:

• Register/unregister with the manager
• Receive notifications via HTTP callbacks
• Handle health check requests

Installation

go get github.com/chronnie/governance

Quick Start

Running the Manager

package main

import (
    "github.com/chronnie/governance/manager"
    "github.com/chronnie/governance/models"
    "time"
)

func main() {
    config := &models.ManagerConfig{
        ServerPort:           8080,
        HealthCheckInterval:  30 * time.Second,
        HealthCheckTimeout:   5 * time.Second,
        HealthCheckRetry:     3,
        NotificationInterval: 60 * time.Second,
        NotificationTimeout:  5 * time.Second,
        EventQueueSize:       1000,
    }

    mgr := manager.NewManager(config)
    mgr.Start()

    // Wait for shutdown signal...
    mgr.Wait()
}

Registering a Service

package main

import (
    "github.com/chronnie/governance/client"
    "github.com/chronnie/governance/models"
)

func main() {
    // Create notification handler
    handler := func(payload *models.NotificationPayload) {
        // Handle notification about service changes
        log.Printf("Service %s changed: %v", payload.ServiceName, payload.Pods)
    }

    // Start notification server
    notifServer := client.NewNotificationServer(9001, handler)
    go notifServer.Start()

    // Create client
    govClient := client.NewClient(&client.ClientConfig{
        ManagerURL:  "http://localhost:8080",
        ServiceName: "user-service",
        PodName:     "user-service-pod-1",
    })

    // Register
    registration := &models.ServiceRegistration{
        ServiceName: "user-service",
        PodName:     "user-service-pod-1",
        Providers: []models.ProviderInfo{
            {
                Protocol: models.ProtocolHTTP,
                IP:       "192.168.1.10",
                Port:     9001,
            },
        },
        HealthCheckURL:  "http://192.168.1.10:9001/health",
        NotificationURL: "http://192.168.1.10:9001/notify",
        Subscriptions:   []string{"order-service", "payment-service"},
    }

    govClient.Register(registration)

    // Your service logic here...

    // Unregister on shutdown
    govClient.Unregister()
}

API Reference

Manager REST API

Register Service

POST /register

{
  "service_name": "user-service",
  "pod_name": "user-service-pod-1",
  "providers": [
    {
      "protocol": "http",
      "ip": "192.168.1.10",
      "port": 8080
    }
  ],
  "health_check_url": "http://192.168.1.10:8080/health",
  "notification_url": "http://192.168.1.10:8080/notify",
  "subscriptions": ["order-service"]
}

Unregister Service

DELETE /unregister?service_name=user-service&pod_name=user-service-pod-1

Get All Services (Debug)

GET /services

Health Check

GET /health

Notification Payload

Services receive notifications at their notification_url:

{
  "service_name": "order-service",
  "event_type": "register|unregister|update|reconcile",
  "timestamp": "2025-12-14T10:00:00Z",
  "pods": [
    {
      "pod_name": "order-service-pod-1",
      "status": "healthy|unhealthy|unknown",
      "providers": [
        {
          "protocol": "http",
          "ip": "192.168.1.20",
          "port": 8080
        }
      ]
    }
  ]
}

Event Processing

The library uses a single event queue with one worker for sequential processing:

1. Register Event (with deadline) - Service registration
2. Unregister Event (with deadline) - Service unregistration
3. Health Check Event (no deadline) - Periodic health verification
4. Reconcile Event (no deadline) - Full state synchronization

Events are processed in FIFO order. Register/Unregister events have deadlines for priority handling, while health check and reconcile events run in the background without deadlines.

Configuration

ManagerConfig

Field	Type	Default	Description
ServerPort	int	8080	HTTP server port
HealthCheckInterval	time.Duration	30s	How often to check service health
HealthCheckTimeout	time.Duration	5s	Timeout for health check HTTP calls
HealthCheckRetry	int	3	Number of retries before marking unhealthy
NotificationInterval	time.Duration	60s	Periodic reconciliation interval
NotificationTimeout	time.Duration	5s	Timeout for notification HTTP calls
EventQueueSize	int	1000	Event queue buffer size

Supported Protocols

• HTTP
• TCP
• PFCP
• GTP
• UDP

Examples

See the examples directory for complete working examples:

• Manager Example - Running the governance manager
• Service Example - Registering a service

License

MIT License