Customer.io Advanced Troubleshooting

Overview

Advanced debugging techniques for diagnosing complex Customer.io integration issues.

Prerequisites

Access to Customer.io dashboard
Application logs access
Understanding of your integration architecture

Troubleshooting Framework

Phase 1: Symptom Identification

1. What is the expected behavior?
2. What is the actual behavior?
3. When did the issue start?
4. How many users/messages affected?
5. Is it consistent or intermittent?

Instructions

Step 1: API Debugging

// lib/debug-client.ts
import { TrackClient, RegionUS } from '@customerio/track';

interface DebugResult {
  success: boolean;
  latency: number;
  requestId?: string;
  error?: {
    code: string;
    message: string;
    details?: any;
  };
}

export class DebugCustomerIO {
  private client: TrackClient;

  constructor() {
    this.client = new TrackClient(
      process.env.CUSTOMERIO_SITE_ID!,
      process.env.CUSTOMERIO_API_KEY!,
      { region: RegionUS }
    );
  }

  async debugIdentify(
    userId: string,
    attributes: Record<string, any>
  ): Promise<DebugResult> {
    const start = Date.now();

    console.log('=== Customer.io Debug: Identify ===');
    console.log('User ID:', userId);
    console.log('Attributes:', JSON.stringify(attributes, null, 2));

    try {
      await this.client.identify(userId, attributes);

      const result: DebugResult = {
        success: true,
        latency: Date.now() - start
      };

      console.log('Result: SUCCESS');
      console.log('Latency:', result.latency, 'ms');

      return result;
    } catch (error: any) {
      const result: DebugResult = {
        success: false,
        latency: Date.now() - start,
        error: {
          code: error.statusCode || 'UNKNOWN',
          message: error.message,
          details: error.response?.body
        }
      };

      console.log('Result: FAILED');
      console.log('Error:', JSON.stringify(result.error, null, 2));

      return result;
    }
  }

  async debugTrack(
    userId: string,
    event: string,
    data?: Record<string, any>
  ): Promise<DebugResult> {
    const start = Date.now();

    console.log('=== Customer.io Debug: Track ===');
    console.log('User ID:', userId);
    console.log('Event:', event);
    console.log('Data:', JSON.stringify(data, null, 2));

    try {
      await this.client.track(userId, { name: event, data });

      return {
        success: true,
        latency: Date.now() - start
      };
    } catch (error: any) {
      return {
        success: false,
        latency: Date.now() - start,
        error: {
          code: error.statusCode || 'UNKNOWN',
          message: error.message
        }
      };
    }
  }
}

Step 2: User Profile Investigation

// scripts/investigate-user.ts
interface UserInvestigation {
  userId: string;
  profile: {
    exists: boolean;
    attributes: Record<string, any>;
    segments: string[];
  };
  activity: {
    lastIdentify: Date;
    lastEvent: Date;
    eventCount24h: number;
    recentEvents: string[];
  };
  delivery: {
    emailsSent: number;
    emailsDelivered: number;
    emailsOpened: number;
    bounces: number;
    complaints: number;
    suppressed: boolean;
  };
  issues: string[];
}

async function investigateUser(userId: string): Promise<UserInvestigation> {
  const investigation: UserInvestigation = {
    userId,
    profile: { exists: false, attributes: {}, segments: [] },
    activity: {
      lastIdentify: new Date(0),
      lastEvent: new Date(0),
      eventCount24h: 0,
      recentEvents: []
    },
    delivery: {
      emailsSent: 0,
      emailsDelivered: 0,
      emailsOpened: 0,
      bounces: 0,
      complaints: 0,
      suppressed: false
    },
    issues: []
  };

  // 1. Check if user exists
  try {
    const profile = await fetchUserProfile(userId);
    investigation.profile = {
      exists: true,
      attributes: profile.attributes,
      segments: profile.segments
    };
  } catch (error) {
    investigation.issues.push('User profile not found in Customer.io');
    return investigation;
  }

  // 2. Check for missing required attributes
  if (!investigation.profile.attributes.email) {
    investigation.issues.push('User missing email attribute - cannot receive emails');
  }

  // 3. Check suppression status
  if (investigation.delivery.suppressed) {
    investigation.issues.push('User is suppressed - no messages will be sent');
  }

  // 4. Check bounce/complaint history
  if (investigation.delivery.bounces > 0) {
    investigation.issues.push(`User has ${investigation.delivery.bounces} bounces`);
  }

  if (investigation.delivery.complaints > 0) {
    investigation.issues.push(`User has ${investigation.delivery.complaints} spam complaints - HIGH PRIORITY`);
  }

  // 5. Check recent activity
  const oneDayAgo = new Date(Date.now() - 24 * 60 * 60 * 1000);
  if (investigation.activity.lastIdentify < oneDayAgo) {
    investigation.issues.push('User profile not updated in 24+ hours');
  }

  return investigation;
}

Step 3: Campaign Debugging

// scripts/debug-campaign.ts
interface CampaignDebug {
  campaignId: number;
  status: 'active' | 'paused' | 'draft';
  trigger: {
    type: string;
    conditions: any;
  };
  audience: {
    segmentId?: number;
    estimatedSize: number;
  };
  recentSends: Array<{
    userId: string;
    timestamp: Date;
    status: string;
  }>;
  issues: string[];
}

async function debugCampaign(campaignId: number): Promise<CampaignDebug> {
  const debug: CampaignDebug = {
    campaignId,
    status: 'draft',
    trigger: { type: '', conditions: {} },
    audience: { estimatedSize: 0 },
    recentSends: [],
    issues: []
  };

  // Fetch campaign details from API
  // Analyze trigger conditions
  // Check audience size
  // Review recent send activity

  // Common issues to check
  if (debug.status !== 'active') {
    debug.issues.push('Campaign is not active');
  }

  if (debug.audience.estimatedSize === 0) {
    debug.issues.push('No users match campaign audience');
  }

  return debug;
}

Step 4: Webhook Debugging

// lib/webhook-debugger.ts
import crypto from 'crypto';

interface WebhookDebugResult {
  signatureValid: boolean;
  payloadParsed: boolean;
  eventsProcessed: number;
  errors: Array<{
    event: string;
    error: string;
  }>;
  processingTime: number;
}

export function debugWebhook(
  rawBody: string,
  signature: string,
  secret: string
): WebhookDebugResult {
  const start = Date.now();
  const result: WebhookDebugResult = {
    signatureValid: false,
    payloadParsed: false,
    eventsProcessed: 0,
    errors: [],
    processingTime: 0
  };

  // 1. Verify signature
  const expectedSignature = crypto
    .createHmac('sha256', secret)
    .update(rawBody)
    .digest('hex');

  result.signatureValid = crypto.timingSafeEqual(
    Buffer.from(signature || ''),
    Buffer.from(expectedSignature)
  );

  if (!result.signatureValid) {
    console.log('Expected signature:', expectedSignature);
    console.log('Received signature:', signature);
    result.processingTime = Date.now() - start;
    return result;
  }

  // 2. Parse payload
  try {
    const payload = JSON.parse(rawBody);
    result.payloadParsed = true;

    // 3. Process events
    for (const event of payload.events || []) {
      try {
        console.log('Processing event:', event.metric, event.event_id);
        result.eventsProcessed++;
      } catch (error: any) {
        result.errors.push({
          event: event.event_id,
          error: error.message
        });
      }
    }
  } catch (error: any) {
    result.errors.push({
      event: 'parse',
      error: error.message
    });
  }

  result.processingTime = Date.now() - start;
  return result;
}

Step 5: Network Debugging

#!/bin/bash
# scripts/debug-network.sh

echo "=== Customer.io Network Diagnostics ==="

# 1. DNS Resolution
echo -e "\n1. DNS Resolution:"
dig track.customer.io +short

# 2. TCP Connectivity
echo -e "\n2. TCP Connectivity:"
nc -zv track.customer.io 443 2>&1

# 3. TLS Handshake
echo -e "\n3. TLS Certificate:"
echo | openssl s_client -connect track.customer.io:443 2>/dev/null | openssl x509 -noout -dates

# 4. API Response Time
echo -e "\n4. API Latency:"
curl -o /dev/null -s -w "Connect: %{time_connect}s\nTTFB: %{time_starttransfer}s\nTotal: %{time_total}s\n" \
  -X POST "https://track.customer.io/api/v1/customers/test" \
  -u "$CUSTOMERIO_SITE_ID:$CUSTOMERIO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email":"test@test.com"}'

# 5. Check for rate limiting
echo -e "\n5. Rate Limit Check:"
for i in {1..5}; do
  curl -s -o /dev/null -w "%{http_code}\n" \
    -X POST "https://track.customer.io/api/v1/customers/test-$i" \
    -u "$CUSTOMERIO_SITE_ID:$CUSTOMERIO_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{"email":"test@test.com"}'
done

Step 6: Incident Response Runbook

## Customer.io Incident Response Runbook

### P1: Complete API Outage
1. Check https://status.customer.io/
2. Verify credentials haven't expired
3. Test with curl directly
4. Enable circuit breaker if available
5. Queue events for retry
6. Notify stakeholders

### P2: High Error Rate (>5%)
1. Check error distribution by type
2. Identify affected operations
3. Review recent code deployments
4. Check for rate limiting
5. Scale down if self-inflicted

### P3: Delivery Issues
1. Check bounce/complaint rates
2. Review suppression list
3. Verify sender reputation
4. Check campaign configuration
5. Review segment conditions

### P4: Webhook Failures
1. Verify webhook secret
2. Check endpoint availability
3. Review payload format
4. Check for duplicate events
5. Verify idempotency handling

Diagnostic Commands

# Check API health
curl -s "https://status.customer.io/api/v2/status.json" | jq '.status'

# Test authentication
curl -u "$CIO_SITE_ID:$CIO_API_KEY" "https://track.customer.io/api/v1/accounts"

# Check user exists
curl -u "$CIO_SITE_ID:$CIO_API_KEY" "https://track.customer.io/api/v1/customers/USER_ID"

Error Handling

Issue	Solution
User not receiving	Check suppression, segments
Events not tracked	Verify user identified first
High latency	Check network, enable pooling

Resources

Next Steps

After troubleshooting, proceed to customerio-reliability-patterns for resilience.

customerio-advanced-troubleshooting

Customer.io Advanced Troubleshooting

Overview

Prerequisites

Troubleshooting Framework

Phase 1: Symptom Identification

Instructions

Step 1: API Debugging

Step 2: User Profile Investigation

Step 3: Campaign Debugging

Step 4: Webhook Debugging

Step 5: Network Debugging

Step 6: Incident Response Runbook

Diagnostic Commands

Error Handling

Resources

Next Steps

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