Customer.io Observability

Output

• Bounded metrics and redacted traces for event acceptance, campaign delivery, errors, latency, and rate-limit headroom.
• An owned alert/runbook path for delivery, authentication, data-quality, and provider incidents.

Examples

Emit an aggregate counter for accepted events and failures by environment and endpoint, never by email address, customer ID, message body, API key, or full payload. Trigger a staging alert with a harmless test event, verify the on-call route, then restore the normal state and record the alert receipt.

Overview

Implement comprehensive observability for Customer.io integrations: Prometheus metrics (latency, error rates, delivery funnel), structured JSON logging with PII redaction, OpenTelemetry tracing, and Grafana dashboard definitions.

Prerequisites

• Customer.io integration deployed
• Prometheus + Grafana (or compatible metrics stack)
• Structured logging system (pino recommended)

Key Metrics to Track

Instructions

Step 1: Prometheus Metrics

// lib/customerio-metrics.ts
import { Counter, Histogram, Gauge, Registry } from "prom-client";

const registry = new Registry();

export const cioMetrics = {
  apiDuration: new Histogram({
    name: "cio_api_duration_ms",
    help: "Customer.io API call duration in milliseconds",
    labelNames: ["operation", "status"] as const,
    buckets: [10, 25, 50, 100, 250, 500, 1000, 2500, 5000],
    registers: [registry],
  }),

  apiRequests: new Counter({
    name: "cio_api_requests_total",
    help: "Total Customer.io API requests",
    labelNames: ["operation"] as const,
    registers: [registry],
  }),

  apiErrors: new Counter({
    name: "cio_api_errors_total",
    help: "Customer.io API errors",
    labelNames: ["operation", "status_code"] as const,
    registers: [registry],
  }),

  emailSent: new Counter({
    name: "cio_email_sent_total",
    help: "Emails sent via Customer.io",
    labelNames: ["type"] as const,  // "transactional" or "campaign"
    registers: [registry],
  }),

  emailBounced: new Counter({
    name: "cio_email_bounced_total",
    help: "Email bounces from Customer.io webhooks",
    registers: [registry],
  }),

  emailComplained: new Counter({
    name: "cio_email_complained_total",
    help: "Spam complaints from Customer.io webhooks",
    registers: [registry],
  }),

  webhookReceived: new Counter({
    name: "cio_webhook_received_total",
    help: "Webhook events received",
    labelNames: ["metric"] as const,
    registers: [registry],
  }),

  queueDepth: new Gauge({
    name: "cio_queue_depth",
    help: "Pending items in Customer.io event queue",
    labelNames: ["queue"] as const,
    registers: [registry],
  }),
};

export { registry };

Step 2: Instrumented Client

// lib/customerio-instrumented.ts
import { TrackClient, APIClient, SendEmailRequest, RegionUS } from "customerio-node";
import { cioMetrics } from "./customerio-metrics";

export class InstrumentedCioClient {
  private track: TrackClient;
  private app: APIClient;

  constructor(siteId: string, trackKey: string, appKey: string) {
    this.track = new TrackClient(siteId, trackKey, { region: RegionUS });
    this.app = new APIClient(appKey, { region: RegionUS });
  }

  async identify(userId: string, attrs: Record<string, any>): Promise<void> {
    const timer = cioMetrics.apiDuration.startTimer({ operation: "identify" });
    cioMetrics.apiRequests.inc({ operation: "identify" });

    try {
      await this.track.identify(userId, attrs);
      timer({ status: "success" });
    } catch (err: any) {
      const code = String(err.statusCode ?? "unknown");
      timer({ status: "error" });
      cioMetrics.apiErrors.inc({ operation: "identify", status_code: code });
      throw err;
    }
  }

  async trackEvent(
    userId: string,
    name: string,
    data?: Record<string, any>
  ): Promise<void> {
    const timer = cioMetrics.apiDuration.startTimer({ operation: "track" });
    cioMetrics.apiRequests.inc({ operation: "track" });

    try {
      await this.track.track(userId, { name, data });
      timer({ status: "success" });
    } catch (err: any) {
      timer({ status: "error" });
      cioMetrics.apiErrors.inc({
        operation: "track",
        status_code: String(err.statusCode ?? "unknown"),
      });
      throw err;
    }
  }

  async sendEmail(request: SendEmailRequest): Promise<any> {
    const timer = cioMetrics.apiDuration.startTimer({ operation: "send_email" });
    cioMetrics.apiRequests.inc({ operation: "send_email" });

    try {
      const result = await this.app.sendEmail(request);
      timer({ status: "success" });
      cioMetrics.emailSent.inc({ type: "transactional" });
      return result;
    } catch (err: any) {
      timer({ status: "error" });
      cioMetrics.apiErrors.inc({
        operation: "send_email",
        status_code: String(err.statusCode ?? "unknown"),
      });
      throw err;
    }
  }
}

Step 3: Structured Logging with PII Redaction

// lib/customerio-logger.ts
import pino from "pino";

const logger = pino({
  name: "customerio",
  level: process.env.CUSTOMERIO_LOG_LEVEL ?? "info",
  redact: {
    paths: [
      "*.email",
      "*.phone",
      "*.ip_address",
      "*.password",
      "attrs.email",
      "attrs.phone",
    ],
    censor: "[REDACTED]",
  },
});

export function logCioOperation(
  operation: string,
  data: {
    userId?: string;
    event?: string;
    latencyMs?: number;
    statusCode?: number;
    error?: string;
    attrs?: Record<string, any>;
  }
): void {
  if (data.error) {
    logger.error({ operation, ...data }, `CIO ${operation} failed`);
  } else {
    logger.info({ operation, ...data }, `CIO ${operation} completed`);
  }
}

// Usage:
// logCioOperation("identify", {
//   userId: "user-123",
//   latencyMs: 85,
//   attrs: { email: "[email protected]", plan: "pro" }
// });
// Output: {"level":"info","operation":"identify","userId":"user-123",
//          "latencyMs":85,"attrs":{"email":"[REDACTED]","plan":"pro"},
//          "msg":"CIO identify completed"}

Step 4: Webhook Metrics Collection

// Integrate with webhook handler (see customerio-webhooks-events skill)
function recordWebhookMetrics(event: { metric: string }): void {
  cioMetrics.webhookReceived.inc({ metric: event.metric });

  switch (event.metric) {
    case "bounced":
      cioMetrics.emailBounced.inc();
      break;
    case "spammed":
      cioMetrics.emailComplained.inc();
      break;
    case "sent":
      cioMetrics.emailSent.inc({ type: "campaign" });
      break;
  }
}

Step 5: Prometheus Metrics Endpoint

// routes/metrics.ts
import { Router } from "express";
import { registry } from "../lib/customerio-metrics";

const router = Router();

router.get("/metrics", async (_req, res) => {
  res.set("Content-Type", registry.contentType);
  res.end(await registry.metrics());
});

export default router;

Step 6: Grafana Dashboard (JSON Model)

{
  "title": "Customer.io Integration",
  "panels": [
    {
      "title": "API Latency (p50/p95/p99)",
      "type": "timeseries",
      "targets": [
        { "expr": "histogram_quantile(0.50, rate(cio_api_duration_ms_bucket[5m]))" },
        { "expr": "histogram_quantile(0.95, rate(cio_api_duration_ms_bucket[5m]))" },
        { "expr": "histogram_quantile(0.99, rate(cio_api_duration_ms_bucket[5m]))" }
      ]
    },
    {
      "title": "Request Rate by Operation",
      "type": "timeseries",
      "targets": [
        { "expr": "rate(cio_api_requests_total[5m])" }
      ]
    },
    {
      "title": "Error Rate %",
      "type": "stat",
      "targets": [
        { "expr": "rate(cio_api_errors_total[5m]) / rate(cio_api_requests_total[5m]) * 100" }
      ]
    },
    {
      "title": "Email Delivery Funnel",
      "type": "bargauge",
      "targets": [
        { "expr": "cio_email_sent_total" },
        { "expr": "cio_email_bounced_total" },
        { "expr": "cio_email_complained_total" }
      ]
    }
  ]
}

Step 7: Alerting Rules

# prometheus/customerio-alerts.yml
groups:
  - name: customerio
    rules:
      - alert: CioHighErrorRate
        expr: rate(cio_api_errors_total[5m]) / rate(cio_api_requests_total[5m]) > 0.05
        for: 5m
        labels: { severity: critical }
        annotations:
          summary: "Customer.io API error rate > 5%"

      - alert: CioHighLatency
        expr: histogram_quantile(0.99, rate(cio_api_duration_ms_bucket[5m])) > 5000
        for: 5m
        labels: { severity: warning }
        annotations:
          summary: "Customer.io p99 latency > 5 seconds"

      - alert: CioHighBounceRate
        expr: rate(cio_email_bounced_total[1h]) / rate(cio_email_sent_total[1h]) > 0.05
        for: 15m
        labels: { severity: warning }
        annotations:
          summary: "Email bounce rate > 5%"

      - alert: CioSpamComplaints
        expr: rate(cio_email_complained_total[1h]) / rate(cio_email_sent_total[1h]) > 0.001
        for: 5m
        labels: { severity: critical }
        annotations:
          summary: "Spam complaint rate > 0.1% — sender reputation at risk"

Error Handling

Resources

• Prometheus Best Practices
• Grafana Dashboard Provisioning
• pino Logger

Next Steps

After observability setup, proceed to customerio-advanced-troubleshooting for debugging.