Skip to main content
EmergentEMERGENT
Emergent SolutionsKnowledge Base

Server-Side Implementation Guide

A step-by-step guide to deploying server-side tagging infrastructure on Google Cloud Platform.

Prerequisites

Before starting, ensure you have:

  • [ ] Google Cloud Platform account with billing enabled
  • [ ] Domain with DNS access (for first-party subdomain)
  • [ ] Existing GTM web container
  • [ ] GA4 property configured
  • [ ] SSL certificate capability

Architecture Overview

┌─────────────────────────────────────────────────────────┐
│                    Your Domain                          │
│                  (example.com)                          │
├─────────────────────────────────────────────────────────┤
│                                                         │
│  ┌─────────────┐         ┌─────────────────────────┐   │
│  │   Website   │         │   First-Party Domain    │   │
│  │             │────────▶│   (gtm.example.com)     │   │
│  │  GTM Web    │         │                         │   │
│  │  Container  │         │   Cloud Run / App Engine│   │
│  └─────────────┘         │   GTM Server Container  │   │
│                          └───────────┬─────────────┘   │
│                                      │                  │
└──────────────────────────────────────│──────────────────┘
                                       │
                                       ▼
                          ┌────────────────────────┐
                          │    Vendor Endpoints    │
                          │  GA4, Meta CAPI, etc.  │
                          └────────────────────────┘

Step 1: Create Server Container

In Google Tag Manager

  1. Navigate to Admin > Container > Create Container
  2. Select Server as the container type
  3. Name your container (e.g., "Server - Production")
  4. Click Create

Initial Configuration

After creation, you'll see provisioning options:

| Option | Best For | Cost | |--------|----------|------| | Automatically provision | Testing only | Free tier limited | | Manual provisioning | Production | Pay-as-you-go |

Always choose manual provisioning for production.

Step 2: Deploy on Google Cloud

Option A: Cloud Run (Recommended)

Cloud Run offers automatic scaling and pay-per-use pricing.

# Set your project
gcloud config set project YOUR_PROJECT_ID

# Enable required APIs
gcloud services enable run.googleapis.com
gcloud services enable secretmanager.googleapis.com

# Deploy the container
gcloud run deploy gtm-server \
  --image gcr.io/cloud-tagging-10302018/gtm-cloud-image:stable \
  --platform managed \
  --region us-central1 \
  --allow-unauthenticated \
  --min-instances 1 \
  --max-instances 10 \
  --memory 512Mi \
  --set-env-vars "CONTAINER_CONFIG=YOUR_CONTAINER_CONFIG"

Option B: App Engine

App Engine provides more predictable pricing for consistent traffic.

Create app.yaml:

runtime: custom
env: flex

automatic_scaling:
  min_num_instances: 1
  max_num_instances: 10
  cool_down_period_sec: 60
  cpu_utilization:
    target_utilization: 0.6

resources:
  cpu: 1
  memory_gb: 0.5
  disk_size_gb: 10

env_variables:
  CONTAINER_CONFIG: "YOUR_CONTAINER_CONFIG"

Deploy:

gcloud app deploy

Container Configuration

Get your container config from GTM:

  1. In GTM Server Container, go to Admin > Container Settings
  2. Copy the Container Config value
  3. Use this value in your deployment

Step 3: Configure First-Party Domain

DNS Setup

Create a subdomain pointing to your server container:

| Record Type | Name | Value | |-------------|------|-------| | CNAME | gtm | your-cloud-run-url.run.app | | A (alternative) | gtm | Your static IP |

SSL Certificate

For Cloud Run with custom domain:

# Map custom domain
gcloud run domain-mappings create \
  --service gtm-server \
  --domain gtm.example.com \
  --region us-central1

SSL is automatically provisioned by Google.

Verify Setup

Test your endpoint:

curl -I https://gtm.example.com/healthy
# Should return 200 OK

Step 4: Configure Web Container

Update GA4 Configuration Tag

In your web GTM container:

  1. Open your Google Tag (GA4 Configuration)
  2. Go to Configuration Settings
  3. Set Server Container URL: https://gtm.example.com
// The tag will now send data to your server instead of Google directly
// Before: www.google-analytics.com
// After: gtm.example.com → Google

First-Party Cookie Setup

Configure first-party cookies in your server container:

  1. In Server GTM, create a GA4 Client
  2. Enable Migrate to first-party cookies
  3. Set Cookie Domain: .example.com

Step 5: Server Container Tags

GA4 Server Tag

  1. Create new tag: GA4
  2. Configure:
    • Measurement ID: G-XXXXXXXXXX
    • Enable Send to GA4

Trigger Configuration

Create a trigger for GA4 events:

| Setting | Value | |---------|-------| | Trigger Type | Custom | | Fire on | Client Name equals GA4 |

Step 6: Verification

Testing Checklist

  • [ ] Server container responds to health checks
  • [ ] First-party domain resolves correctly
  • [ ] SSL certificate is valid
  • [ ] GA4 data appears in DebugView
  • [ ] Cookies are set on first-party domain
  • [ ] No CORS errors in browser console

Preview Mode

Use GTM Preview for both containers:

  1. Start Preview in web container
  2. Start Preview in server container
  3. Verify event flow from web → server → GA4

Debug Request

# Send test event to your server
curl -X POST https://gtm.example.com/g/collect \
  -H "Content-Type: application/json" \
  -d '{"client_id":"test","events":[{"name":"test_event"}]}'

Scaling Considerations

Cloud Run Scaling

# Recommended production settings
min-instances: 2
max-instances: 100
concurrency: 80
cpu: 1
memory: 1Gi

Monitoring

Set up alerts for:

| Metric | Warning | Critical | |--------|---------|----------| | Request latency | > 500ms | > 2s | | Error rate | > 1% | > 5% | | Instance count | > 50% max | > 80% max |

Cost Optimization

| Optimization | Impact | |--------------|--------| | Minimum instances: 1-2 | Reduce cold starts | | Request batching | Lower request count | | Regional deployment | Reduce latency | | Committed use discounts | 20-40% savings |

Common Issues

Container Not Starting

# Check logs
gcloud run logs read --service gtm-server --limit 50

CORS Errors

Ensure your server allows requests from your domain:

  • The GTM server image handles this automatically
  • Verify no proxy is stripping headers

Cookie Not Setting

  • Verify SSL is working
  • Check cookie domain configuration
  • Ensure SameSite settings are correct

Previous: Server-Side Overview Next: Marketing Pixels