Customer.io Upgrade & Migration

Current State

!npm list customerio-node 2>/dev/null | grep customerio || echo 'customerio-node: not installed' !npm view customerio-node version 2>/dev/null || echo 'Cannot check latest version'

Overview

Plan and execute customerio-node SDK upgrades safely: assess current version, review breaking changes, apply code migrations, and validate with staged rollout.

Prerequisites

• Current SDK version identified (npm list customerio-node)
• Test environment available
• Version control for rollback

Major Version Migration Reference

Legacy CustomerIO to Modern TrackClient + APIClient

Older versions of customerio-node used a single CustomerIO class. Modern versions split into TrackClient (tracking) and APIClient (transactional/broadcasts).

// BEFORE — Legacy pattern (customerio-node < 2.x)
const CustomerIO = require("customerio-node");
const cio = new CustomerIO(siteId, apiKey);
cio.identify("user-1", { email: "user@example.com" });
cio.track("user-1", { name: "event_name" });

// AFTER — Modern pattern (customerio-node >= 2.x)
import { TrackClient, APIClient, RegionUS } from "customerio-node";

const cio = new TrackClient(siteId, apiKey, { region: RegionUS });
await cio.identify("user-1", { email: "user@example.com" });
await cio.track("user-1", { name: "event_name", data: {} });

const api = new APIClient(appApiKey, { region: RegionUS });
await api.sendEmail(request);

Key changes:

• TrackClient replaces CustomerIO for identify/track
• APIClient is new — handles transactional + broadcasts
• Region is now explicit (RegionUS or RegionEU)
• Methods return Promises (must await)
• Event tracking uses { name, data } object instead of positional args

Instructions

Step 1: Assess Current Version

// scripts/cio-version-check.ts
import { readFileSync, existsSync } from "fs";

function assessVersion() {
  // Check installed version
  const lockPath = "package-lock.json";
  if (existsSync(lockPath)) {
    const lock = JSON.parse(readFileSync(lockPath, "utf-8"));
    const installed =
      lock.packages?.["node_modules/customerio-node"]?.version ??
      lock.dependencies?.["customerio-node"]?.version ??
      "not found in lockfile";
    console.log(`Installed: customerio-node@${installed}`);
  }

  // Check package.json declared version
  const pkg = JSON.parse(readFileSync("package.json", "utf-8"));
  const declared = pkg.dependencies?.["customerio-node"] ?? "not declared";
  console.log(`Declared: ${declared}`);

  // Search for usage patterns
  console.log("\nUsage pattern check:");
  console.log("- Look for 'new CustomerIO(' → legacy pattern, needs migration");
  console.log("- Look for 'new TrackClient(' → modern pattern");
  console.log("- Look for 'RegionUS/RegionEU' → region-aware (good)");
}

assessVersion();

Step 2: Review Breaking Changes

// Common breaking changes between major versions:

// v1.x → v2.x:
// - CustomerIO class → TrackClient + APIClient
// - Callbacks → Promises (async/await)
// - Region parameter added (defaults to US)
// - SendEmailRequest constructor changed

// v2.x → v3.x:
// - Import path may change
// - TypeScript types improved
// - Error object structure may change

// Always check the official changelog:
// https://github.com/customerio/customerio-node/blob/main/CHANGELOG.md

Step 3: Create Migration Wrapper

// lib/customerio-migration.ts
// Adapter that supports both old and new patterns during migration

import { TrackClient, APIClient, RegionUS } from "customerio-node";

export class CioMigrationClient {
  private trackClient: TrackClient;
  private apiClient: APIClient | null;

  constructor(config: {
    siteId: string;
    trackApiKey: string;
    appApiKey?: string;
    region?: "us" | "eu";
  }) {
    const region = config.region === "eu"
      ? (await import("customerio-node")).RegionEU
      : RegionUS;

    this.trackClient = new TrackClient(config.siteId, config.trackApiKey, {
      region,
    });

    this.apiClient = config.appApiKey
      ? new APIClient(config.appApiKey, { region })
      : null;
  }

  // Legacy-compatible identify (accepts both old and new signatures)
  async identify(userId: string, attrs: Record<string, any>): Promise<void> {
    // Ensure timestamps are in seconds, not milliseconds
    if (attrs.created_at && attrs.created_at > 1e12) {
      attrs.created_at = Math.floor(attrs.created_at / 1000);
    }
    await this.trackClient.identify(userId, attrs);
  }

  // Legacy-compatible track (normalizes data format)
  async track(
    userId: string,
    eventOrOpts: string | { name: string; data?: Record<string, any> },
    data?: Record<string, any>
  ): Promise<void> {
    if (typeof eventOrOpts === "string") {
      // Legacy: track("user", "event_name", { key: "value" })
      await this.trackClient.track(userId, {
        name: eventOrOpts,
        data: data ?? {},
      });
    } else {
      // Modern: track("user", { name: "event_name", data: {} })
      await this.trackClient.track(userId, eventOrOpts);
    }
  }

  get app(): APIClient {
    if (!this.apiClient) {
      throw new Error("App API key not configured");
    }
    return this.apiClient;
  }
}

Step 4: Update and Test

# Update to latest version
npm install customerio-node@latest

# Run your test suite
npm test

# Run integration tests against dev workspace
npx dotenv -e .env.development -- npx vitest run tests/customerio

Step 5: Migration Test Suite

// tests/cio-migration.test.ts
import { describe, it, expect } from "vitest";
import { TrackClient, APIClient, RegionUS } from "customerio-node";

const cio = new TrackClient(
  process.env.CUSTOMERIO_SITE_ID!,
  process.env.CUSTOMERIO_TRACK_API_KEY!,
  { region: RegionUS }
);

describe("Post-migration validation", () => {
  const testId = `migration-test-${Date.now()}`;

  it("identify works with new client", async () => {
    await expect(
      cio.identify(testId, {
        email: `${testId}@test.example.com`,
        created_at: Math.floor(Date.now() / 1000),
      })
    ).resolves.not.toThrow();
  });

  it("track works with object format", async () => {
    await expect(
      cio.track(testId, { name: "migration_test", data: { version: "new" } })
    ).resolves.not.toThrow();
  });

  it("suppress and destroy work", async () => {
    await cio.suppress(testId);
    await expect(cio.destroy(testId)).resolves.not.toThrow();
  });
});

Step 6: Staged Rollout with Feature Flag

// Use feature flag to gradually migrate traffic
import { createHash } from "crypto";

function useNewSdk(userId: string, rolloutPercent: number): boolean {
  const hash = createHash("md5").update(`cio-migration-${userId}`).digest("hex");
  return parseInt(hash.substring(0, 8), 16) % 100 < rolloutPercent;
}

// In your application code:
if (useNewSdk(userId, 10)) {
  // New SDK path
  await newClient.identify(userId, attrs);
} else {
  // Legacy SDK path (until migration complete)
  await legacyClient.identify(userId, attrs);
}

Migration Checklist

• Current version documented
• Target version identified
• Breaking changes reviewed (CHANGELOG.md)
• Code changes implemented (TrackClient, region, async/await)
• Unit tests passing
• Integration tests passing against dev workspace
• Staging deployment successful
• Feature flag for staged rollout ready
• Rollback plan documented (pin old version in package.json)
• Team notified of migration timeline

Error Handling

Issue	Solution
TrackClient is not a constructor	Old import style — use import { TrackClient } from "customerio-node"
region is not defined	Import RegionUS or RegionEU from customerio-node
Methods not returning Promises	Upgrade to latest — old versions used callbacks
TypeError: cio.track is not a function	Using APIClient instead of TrackClient for tracking

Resources

• customerio-node CHANGELOG
• customerio-node Releases
• npm customerio-node

Next Steps

After successful migration, proceed to customerio-ci-integration for CI/CD setup.