Billing Service

The Billing Service manages subscriptions, usage tracking, and quota enforcement. It ensures tenants stay within their plan limits and handles overage calculations.

Overview

This service integrates closely with the Tenant Service to enforce resource limits based on subscription tiers (Starter, Growth, Enterprise).

Key Features

• Subscription Management: Tier-based plans.
• Usage Tracking: Monitors messages, storage, and outlets.
• Quota Enforcement: Hard limits at 105% usage.
• Deposit System: Prepaid balance for overages.

Architecture

Component	Tech Stack	Description
Language	Go 1.21	High performance
Framework	Gin	HTTP web framework
Database	PostgreSQL	Shared with Tenant Service

API Reference

Get Subscription

Retrieves current plan details.

• Endpoint: GET /api/v1/billing/tenants/:tenantId/subscription

Check Quota

Verifies if an action is allowed based on current usage.

• Endpoint: POST /api/v1/billing/tenants/:tenantId/quota/check
• Body:

{
  "usageType": "messages",
  "count": 1
}

• Response (Allowed):

{
  "allowed": true,
  "percent": 90.0
}

• Response (Blocked):

{
  "allowed": false,
  "reason": "Quota exceeded (105% hard limit)"
}

Record Usage

Increments usage counters.

• Endpoint: POST /api/v1/billing/tenants/:tenantId/usage
• Body:

{
  "usageType": "messages",
  "count": 1
}

Add Deposit

Adds funds for overage coverage.

• Endpoint: POST /api/v1/billing/tenants/:tenantId/deposit
• Body:

{
  "amount": 100.00
}

tId/deposit`: Add funds.

• GET /api/v1/billing/tenants/:tenantId/quota: Check quota status.bscription Management**: Tracks tenant subscription status (SaaS model).

Data Model

• Invoice: Record of a payment request.