README

This Magento 2 module provides a self-hosted Google Tag Manager (GTM) integration and a lightweight Klaro! consent manager fully optimized for the Hyvä theme.
It delivers a complete dataLayer, supports all eCommerce events, and allows custom payloads for multi-platform tracking.

The module supports multistore. This means that with this module and a single GTM server-side container you can handle any number of stores within one Magento installation. The data is separated based on the GA4 ID variable, which is passed into the payload from the module’s configuration.

The module can be quickly and easily refactored programmatically to serve solely as a dataLayer provider and to work with a cookie notice module other than Klaro.

✨ Features

• ✅ Full eCommerce event tracking for GTM
  • view_item
  • view_item_list
  • add_to_cart
  • remove_from_cart (detected via cart comparison)
  • checkout and purchase events
• ✅ Ultra-light Klaro! CMP integration for GDPR/consent management
• ✅ First-party cookies storage:
  • Improves attribution accuracy
  • Reduces tracking loss caused by third-party cookie restrictions (ITP, Safari, Firefox)
  • Increases data reliability for remarketing and analytics
• ✅ Defer-loaded gtag.js:
  • Does not block rendering
  • No impact on LCP (Largest Contentful Paint)
  • Keeps Lighthouse performance score high
• ✅ Flexible payloads:
  • Can trigger not only Google tags but also Facebook Pixel, TikTok, LinkedIn and any other GTM-integrated platforms
• ✅ Compatible with Hyvä Checkout
• ✅ Configurable through Magento admin
• ✅ Extremely lightweight and performant

⚙️ Configuration

0. Klaro CMP

• Start with the Klaro config file:
  src/view/frontend/web/js/klaro-config.js
• Define purposes (goals) and services according to your tracking needs.
• To remain compliant with Google Consent Mode v2 (GCM v2), you must map Klaro services to Google signals.
  This is mandatory for GA4 / Google Ads to work properly.

1. Magento Admin Configuration

The module settings are available in:
Stores → Configuration → General → Centrum GTM

Required fields:

• GA4 Measurement ID (format: G-XXXXXX)
• GTM Server-Side endpoint URL – the endpoint where payloads will be sent. Example:

  https://www.example.com/data
  

Optional fields:

• Conversion Label
• Conversion ID
  (used for Google Ads remarketing and conversions)

2. GTM Server-Side Container

• In Google Tag Manager UI, create a Server container.
• Deploy the GTM SS container from the official Docker image.
• To support first-party cookies, the container must run on your own domain (e.g. https://www.example.com/data).
• Update your Nginx / Apache configuration to proxy requests to the GTM SS container on /data.

3. How the Module Works

• The module sends all event payloads (e.g. view_item, add_to_cart, purchase) to the GTM SS endpoint.
• The GTM SS container receives them via the Client component.
• Based on those events, GTM SS fires the configured tags (GA4, Ads, Meta, TikTok, custom tags, etc.).

4. GTM SS Setup

To unlock full potential:

• Configure GTM SS with variables, triggers, and tags to handle the payload.
• Map Magento eCommerce events to GA4 / Ads / other platforms according to your business needs.
• Ensure Klaro consent signals are respected in GTM SS (via Consent Mode v2 mapping).

⚙️ Requirements

• Magento 2.4.x
• Hyvä Theme ^1.3
• GTM Server-Side container (GTMss) properly installed and configured

🔧 Installation

composer require centrum/module-gtm
bin/magento setup:upgrade

💡 Why First-Party Cookies?

This module stores cookies as 1st-party (set from your own domain, not from google.com).

Benefits:

• Survives modern browser restrictions (Safari ITP, Firefox ETP).
• Much longer lifetime vs. 3rd-party cookies.
• Significantly improves attribution for Google Ads, GA4, Meta Ads, TikTok Ads.
• Increases match rate for remarketing and conversion tracking.

In short: better tracking, more accurate campaigns, less data loss.

📦 Professional Support

• The module is free and open-source.
• Need help with GTM Server-Side setup & domain integration?
  👉 We provide one-time setup support for 1500 USD.
  This includes:
  • GTMss installation on your own domain
  • Variable & trigger configuration
  • Verification and testing of event flow

Contact: biuro@centrumswiatla.com.pl

License

MIT