API Billing Service Onboarding

Automates the complete process of adding a new third-party API service to the AWS Lambda-based billing and quota monitoring system.

Purpose

This skill provides a step-by-step workflow for integrating new API services into an existing AWS monitoring infrastructure that tracks account balances, quotas, and usage across multiple third-party services. The system monitors services every 30 minutes, pushes metrics to CloudWatch, triggers alerts via SNS to Feishu, and visualizes data on a centralized dashboard.

When to Use

Use this skill when the user requests to:

• Add monitoring for a new API service's balance, quota, or credits
• Set up alerts for low balance/quota on a third-party service
• Integrate a new service into the billing dashboard
• Monitor remaining usage or spending on an external API

Common trigger phrases:

• "Add [Service] to monitoring"
• "Monitor [Service] API balance"
• "Set up quota alerts for [Service]"
• "Track [Service] credits in dashboard"

Project Context

The monitoring system is located in /path/to/monitoring-system/ and consists of:

• Runtime: Node.js 18.x (TypeScript)
• Cloud Platform: AWS Lambda + CloudWatch + Secrets Manager + EventBridge + SNS
• Commands: Managed via just (see justfile)
• Architecture: EventBridge (30min) → Lambda → CloudWatch Metrics → Alarms → SNS → Feishu

Key Files:

• adapters/*.ts - API service adapters
• adapters/index.ts - Adapter registry
• src/handler.ts - Lambda entry point
• src/types.ts - BillingMetric interface
• src/metrics.ts - CloudWatch metric publishing
• CLAUDE.md - Project documentation

Workflow

Step 1: Gather Service Information

Before starting implementation, collect the following information from the user:

1. Service name (e.g., "resend", "sendgrid")
2. API documentation URL (especially balance/quota endpoints)
3. API Key/Token (will be stored in Secrets Manager)
4. Alert threshold (absolute value or percentage)
5. Service display name (for Dashboard labels)

Questions to ask:

• "What is the API endpoint for checking balance/quota?"
• "How does the API authenticate? (Bearer token, API key header, query param?)"
• "What response format does the API return? (JSON structure)"
• "What threshold should trigger an alert? (e.g., remaining < 100, or < 5%)"
• "What unit does the service use? (USD, credits, emails, requests?)"

Step 2: Create API Adapter

Create a new TypeScript adapter file at adapters/<service_name>.ts.

Refer to: references/adapter-templates.md for three common adapter patterns:

• Standard JSON response with balance fields
• Response headers containing quota information
• Prepaid credits with no total amount

The adapter must:

1. Call the service's API to retrieve balance/quota
2. Mask the API key (show first 6 and last 6 characters)
3. Return a BillingMetric object with:
   • service: lowercase service identifier
   • apiKeyMask: masked API key
   • total: total quota/balance
   • remaining: remaining quota/balance
   • remainingRatio: remaining/total (0-1)
   • currency (optional): "USD", "CNY", etc.
   • unit (optional): "credits", "emails", "requests"

Use the Read tool to examine existing adapters for reference:

• adapters/resend.ts - Response header quota pattern
• adapters/serper.ts - Prepaid credits pattern
• adapters/scrapedo.ts - Standard JSON response pattern

Step 3: Register Adapter

Edit adapters/index.ts:

1. Import the new adapter function
2. Add entry to the adapters object

Example:

import { fetchServiceName } from "./service_name";

export const adapters = {
  // ... existing adapters
  service_name: fetchServiceName,
};

Step 4: Update Lambda Handler

Edit src/handler.ts to add the service call logic.

Location: Insert before console.log("✅ Billing check completed")

Pattern:

// <Service Display Name>
if (apiKeys.<service_name>) {
  try {
    console.log("🔍 Fetching <Service> quota...");
    const metric = await adapters.<service_name>(apiKeys.<service_name>);
    await pushMetrics(metric);
    results.push({
      service: "<service_name>",
      status: "success",
      remaining: metric.remaining,
      total: metric.total,
      ratio: metric.remainingRatio
    });
  } catch (error: any) {
    console.error("❌ <Service> error:", error.message);
    results.push({ service: "<service_name>", status: "error", error: error.message });
  }
}

Step 5: Add API Key to Secrets Manager

Use the helper script to safely add the API key:

scripts/add-secret-key.sh <service_name> <api_key>

Manual alternative:

# Get current secrets
aws secretsmanager get-secret-value \
  --secret-id api-billing-monitor/keys \
  --query SecretString --output text > /tmp/secrets.json

# Edit /tmp/secrets.json to add: "<service_name>": "<api_key>"

# Update secrets
aws secretsmanager update-secret \
  --secret-id api-billing-monitor/keys \
  --secret-string file:///tmp/secrets.json

Step 6: Build and Deploy

# Quick deployment (recommended)
just deploy-quick

# Or full deployment with verbose output
just deploy

Verify deployment:

# Trigger Lambda manually
just invoke

# Check logs for the new service
just logs | grep <service_name>

Step 7: Create CloudWatch Alarm

Choose the appropriate alarm strategy:

Strategy A: Absolute Value Threshold (for fixed quotas):

aws cloudwatch put-metric-alarm \
  --alarm-name "<Service>-Low-Balance" \
  --namespace "ThirdPartyAPIBilling" \
  --metric-name "Remaining" \
  --dimensions Name=Service,Value=<service_name> \
  --statistic Average \
  --period 1800 \
  --evaluation-periods 1 \
  --threshold <absolute_value> \
  --comparison-operator LessThanThreshold \
  --alarm-actions "arn:aws:sns:us-east-1:830101142436:CloudWatchAlarmsToFeishu" \
  --alarm-description "<Service> remaining balance below <threshold>"

Strategy B: Percentage Threshold (for variable quotas):

aws cloudwatch put-metric-alarm \
  --alarm-name "<Service>-Low-Ratio" \
  --namespace "ThirdPartyAPIBilling" \
  --metric-name "RemainingRatio" \
  --dimensions Name=Service,Value=<service_name> \
  --statistic Average \
  --period 1800 \
  --evaluation-periods 1 \
  --threshold 0.05 \
  --comparison-operator LessThanThreshold \
  --alarm-actions "arn:aws:sns:us-east-1:830101142436:CloudWatchAlarmsToFeishu" \
  --alarm-description "<Service> remaining ratio below 5%"

Verify alarm creation:

just alarms | grep <Service>

Step 8: Update CloudWatch Dashboard

Use the helper script to automatically add the service to the dashboard:

scripts/add-to-dashboard.sh <service_name> "<Service Display Name>" "<masked_api_key>"

Manual alternative:

1. Get current dashboard configuration:

   bashCopy

   aws cloudwatch get-dashboard \
     --dashboard-name "API-Billing-Monitor" \
     --query "DashboardBody" \
     --output text > /tmp/dashboard.json
   

2. Edit /tmp/dashboard.json to add the service in 4 locations:

   • "所有服务剩余比例趋势" metrics array
   • "当前剩余比例" metrics array
   • Create a new widget (optional, for detailed service chart)
   • "当前剩余额度/Credits" metrics array

3. Update dashboard:

   bashCopy

   aws cloudwatch put-dashboard \
     --dashboard-name "API-Billing-Monitor" \
     --dashboard-body file:///tmp/dashboard.json
   

Refer to: references/dashboard-widget-template.json for widget JSON structure examples.

Step 9: Update Project Documentation

Edit CLAUDE.md to add the new service to the "已接入服务" table:

| <service_name> | <unit> | <threshold> | <description> |

Step 10: Verification

Run the complete verification checklist:

# 1. Trigger monitoring
just invoke

# 2. Check logs for successful execution
just logs | grep "<service_name>"
# Expected: "✅ Metrics pushed for <service_name>"

# 3. Verify metrics in CloudWatch
aws cloudwatch list-metrics \
  --namespace ThirdPartyAPIBilling \
  --dimensions Name=Service,Value=<service_name>

# 4. Check alarm status
just alarms | grep "<Service>"

# 5. View current status
just status

# 6. Visit dashboard
echo "https://us-east-1.console.aws.amazon.com/cloudwatch/home?region=us-east-1#dashboards/dashboard/API-Billing-Monitor"

Success criteria:

• ✅ Lambda logs show successful metric push
• ✅ CloudWatch metrics exist for the service
• ✅ Alarm is in OK or ALARM state (not INSUFFICIENT_DATA)
• ✅ Dashboard displays the service in all charts
• ✅ Service appears in just status output

Troubleshooting

Lambda execution fails:

• Check logs: just logs
• Verify API key in Secrets Manager: just secrets-full
• Test API endpoint manually with curl/Postman

Metrics not appearing in CloudWatch:

• Confirm Lambda executed successfully: just invoke
• Check for errors in adapter code
• Verify metric push logic in logs

Dashboard shows no data:

• Wait 30 minutes for first execution cycle
• Confirm metrics exist: aws cloudwatch list-metrics --namespace ThirdPartyAPIBilling
• Verify Dashboard JSON syntax

Alarm not triggering:

• Check alarm configuration: aws cloudwatch describe-alarms --alarm-names "<Service>-Low-Balance"
• Verify metric data points exist
• Test alarm: just test-alarm <Service>-Low-Balance

Notes

• The system runs on a 30-minute schedule via EventBridge
• All API keys are stored securely in AWS Secrets Manager
• Alarms notify via SNS to Feishu webhook
• The CloudWatch namespace is ThirdPartyAPIBilling
• Common dimension: Service=<service_name>, APIKey=<masked_key>

For detailed examples and edge cases, refer to references/service-integration-examples.md.