Implementing Google Cloud CDN: An In-Depth Guide

Content Delivery Networks (CDNs) have become a critical part of today‘s web infrastructure. With users expecting fast, reliable content delivery, CDNs help replicate and cache content across geographically distributed edge servers. This brings content physically closer to end users allowing for high performance across diverse locations.

The global CDN market has expanded rapidly, projected to reach $31 billion by 2024. New solutions have emerged from major cloud providers aiming to leverage their existing infrastructure. Google Cloud CDN brings Google‘s network edge closer alongside comprehensive services for modern application requirements.

This guide will walk you through implementing and configuring Cloud CDN for your website or application hosted on Google Cloud Platform (GCP). I‘ll explain what Google Cloud CDN offers, when it fits your needs, along with an in-depth setup tutorial from scratch.

Cloud CDN Architecture

Before jumping into implementation, it‘s useful to understand what happens behind the scenes when a user request is served through Cloud CDN.

As depicted below, content is cached across Google‘s extensive network of 130+ edge PoPs (Point of Presence) when requested first time. Subsequent requests are served from the nearest cache location instead of the origin server. This reduces round trip time significantly since cached content is available at the network edge closest to users.


Figure 1: Simplified architecture of Google Cloud CDN with edge caching

Some key design elements:

  • Global HTTP load balancing provides anycast IP to route a user to the nearest available cache
  • Requests are sent over Google‘s high quality network minimizing internet hops
  • Content is cached at the edge for best latency delivery to that region
  • Cache can be custom configured via edge dictionaries
  • Detailed logging and analytics available

Understanding the basics of how CDNs function helps utilize them effectively for faster content delivery.

Key Advantages of Google Cloud CDN

While there are multiple CDN providers, Google Cloud CDN differentiates itself on the following aspects:

1. Leverages Google‘s networkEdge – With 900+ network edge locations, content is served from within Google‘s network as much as possible maximizing efficiency.

2. POP footprint across 130+ locations globally – Extensive reach ensures low latency from anywhere.

3. HTTP/2 support – Enables faster page loads via improved protocol.

4. Optimized for GCP services – Integrates natively with Google infrastructure like Cloud Storage, Cloud Load Balancing.

5. Real-time logging and analytics – Included Stackdriver analytics for in-depth performance monitoring.

6. Custom edge logic – Ability to configure edges by region/country for granular control.

7. Cost effectivePricing model allows optimizing TCO efficiently.

Based on these characteristics, if your application audience is geographically dispersed especially leveraging other GCP services, Cloud CDN is an excellent choice.

Next, let‘s get into the implementation.

Step-by-Step Guide: Setting up Google Cloud CDN

The following steps will help you enable and configure Cloud CDN for an existing website or application running on Google Cloud Platform.


  • Site/app hosted on GCP behind a load balancer
  • Static assets stored in Cloud Storage bucket
  • Custom domain connected with Cloud DNS

1. Configure Load Balancer as CDN Origin

Cloud CDN can only use load balancers as origins currently, so first ensure you have an HTTP(S) load balancer setup (SSL recommended but optional).


Under the hood this runs in TCP passthrough mode without attempting TLS termination or proxying. The LB simply round robins traffic to your application backend.

Static assets can be served directly from Cloud Storage buckets while dynamic content goes through the compute instance behind LB.

2. Create Backend Bucket

To link the storage bucket containing static assets, add it as a backend bucket:

Navigation Menu > Network Services > Cloud CDN > Create Backend Bucket

  • Choose the already configured storage bucket
  • Select the hosted content path
  • Leave other settings as default

This backend now ties your storage bucket that will act as the origin for static content through the CDN.

3. Configure URL Redirects

Under URL redirects, customize path handling from LB. For instance:

/images* -> Backend bucket serving static files
/*       -> Load balancer backend  

This routes all /images requests directly to Cloud Storage bucket via CDN while rest goes to the compute instance.

Fine tune caching expiration times, geo access etc on this section. Terraform helps automate configuring backend buckets.

4. Enable Cloud CDN on the Load Balancer

Navigate to Network Services > Cloud CDN and select the previously created load balancer as the origin. This activates Cloud CDN for requests coming to this LB.

Customize other specifications like:

  • Caching rules
  • Session affinity
  • Geo blocking /allow lists
  • Logging settings

These can be tuned later as well based on traffic patterns for optimizing performance.

5. Update DNS Records to Enable CDN

A final vital step is updating your domain‘s DNS records via Cloud DNS to point traffic through the Cloud CDN IP address instead of direct to GCP LB.

Common record types to update:

A    --> CDN load balancer IPv4
AAAA --> CDN load balancer IPv6 

Migrate any existing domain to Cloud DNS if currently managed externally. This allows controlling failovers, geo routing policies from one console.

Once DNS migrations are complete, traffic will flow via Cloud CDN edge servers before origin rather than directly hitting GCP LB. Verify functionality before switching completely.

Testing Cloud CDN Deployment

After the DNS switcheroo, test by accessing your site and validating assets are served through CDN – observable via headers:

Response Headers:

x-cache: HIT
via: 1.1 google

The cache hit indicates requests are being served from edge caches globally versus the origin.

Compare performance against baseline metrics before setup to validate improvements:

  • Latency -TTFB, complete load time from multiple regions
  • Throughput – bandwidth metrics
  • Cache efficiency – hit ratio, stats from Stackdriver

Tune configurations further based on the analytics to optimize caching, availability etc. as needed.

Optimizing Costs

At $0.10 per GB serving cost for Cloud CDN, pricing is quite reasonable specially for larger volumes following a long tail model. However, further optimizations can minimize overhead:

  • Set optimal cache expiration based on content update frequencies to maximize cache reuse.
  • Enable compression to reduce response payload sizes.
  • Route dynamically generated content directly to origin avoiding unnecessary caching.
  • Consider regional CDNs if audiences are concentrated in certain areas.

Always evaluate usage against alternatives or hosting directly on GCP to pick most economical path.


In summary, Google Cloud CDN allows leveraging Google‘s edge network to build high performance web architectures. This guide covered end-to-end implementation steps explaining core concepts along the way.

Feel free to post any questions in comments below and I‘ll be glad to help out!