Cloud CDN integration in GCP - Step-by-Step Execution

Process Flow - Cloud CDN integration

Create Backend Service

↓

Enable Cloud CDN on Backend

↓

Create URL Map

↓

Create Target HTTP(S) Proxy

↓

Create Global Forwarding Rule

↓

Client Requests -> CDN Cache

↓

Cache Hit?

Yes→Serve from Cache

No↓

Fetch from Backend

↓

Cache Response

↓

Serve to Client

This flow shows how to set up Cloud CDN with a backend service and how client requests are served from cache or backend.

Execution Sample

GCP

gcloud compute backend-services create my-backend \
  --protocol HTTP --port-name http --global

gcloud compute backend-services update my-backend \
  --enable-cdn --global

gcloud compute url-maps create my-map \
  --default-service my-backend

gcloud compute target-http-proxies create my-proxy \
  --url-map my-map

gcloud compute forwarding-rules create my-rule \
  --global --target-http-proxy my-proxy --ports 80

This code creates a backend service, enables Cloud CDN, sets up URL map, proxy, and forwarding rule to serve cached content globally.

Process Table

Step	Action	Resource Created/Updated	Effect	Next Step
1	Create backend service	Backend Service 'my-backend'	Backend ready to serve HTTP	Enable CDN on backend
2	Enable CDN	Backend Service 'my-backend'	CDN caching enabled	Create URL map
3	Create URL map	URL Map 'my-map'	Routes requests to backend	Create target HTTP proxy
4	Create target HTTP proxy	Target HTTP Proxy 'my-proxy'	Handles HTTP requests	Create forwarding rule
5	Create global forwarding rule	Forwarding Rule 'my-rule'	Listens on port 80 globally	Ready to serve requests
6	Client sends request	Request received	Check cache for content	Cache hit?
7	Cache hit	Serve cached content	Fast response from CDN	End
8	Cache miss	Fetch from backend	Backend serves content	Cache response and serve
9	Cache response	Content cached	Future requests faster	Serve to client
10	Serve to client	Response sent	Client receives content	End

💡 Execution stops after serving client content either from cache or backend.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	After Step 7/8	After Step 9	Final
Backend Service	None	Created	CDN Enabled	CDN Enabled	CDN Enabled	CDN Enabled	CDN Enabled	CDN Enabled	CDN Enabled	CDN Enabled
URL Map	None	None	None	Created	Created	Created	Created	Created	Created	Created
Target HTTP Proxy	None	None	None	None	Created	Created	Created	Created	Created	Created
Forwarding Rule	None	None	None	None	None	Created	Created	Created	Created	Created
Cache Status	Empty	Empty	Empty	Empty	Empty	Empty	Check Cache	Hit or Miss	Updated if Miss	Hit or Miss
Client Response	None	None	None	None	None	None	Waiting	From Cache or Backend	From Cache or Backend	Sent

Key Moments - 3 Insights

Why do we enable CDN after creating the backend service and not before?

Because the backend service must exist first to enable CDN on it. See execution_table rows 1 and 2 where backend is created first, then CDN is enabled.

What happens when a client request results in a cache miss?

The request goes to the backend service to fetch content, which is then cached for future requests. This is shown in execution_table rows 8 and 9.

Why do we need a URL map and target HTTP proxy in this setup?

The URL map directs requests to the backend service, and the target HTTP proxy handles incoming HTTP requests globally. This routing setup is essential before creating the forwarding rule (rows 3 and 4).

Visual Quiz - 3 Questions

Look at the execution_table, at which step is Cloud CDN enabled on the backend service?

A Step 1

B Step 2

C Step 3

D Step 5

💡 Hint

Check the 'Action' and 'Effect' columns in execution_table row 2.

According to variable_tracker, what is the cache status after step 7?

A Empty

B Check Cache

C Hit or Miss

D Updated if Miss

💡 Hint

Look at the 'Cache Status' row and the column 'After Step 7/8' in variable_tracker.

If the forwarding rule was not created, what would be the impact on serving client requests?

A Requests would still be served from cache

B Requests would be routed directly to backend without caching

C Requests would not reach the proxy and fail

D Requests would be served from a different region

💡 Hint

Refer to execution_table row 5 and the role of forwarding rules in routing.

Concept Snapshot

Cloud CDN integration steps:
1. Create backend service.
2. Enable CDN on backend.
3. Create URL map to route requests.
4. Create target HTTP proxy.
5. Create global forwarding rule.
Client requests hit CDN cache first; cache miss fetches from backend.

Full Transcript

This visual execution trace shows how to integrate Cloud CDN with a backend service on Google Cloud Platform. First, a backend service is created to serve HTTP traffic. Then, Cloud CDN is enabled on this backend to cache content globally. A URL map is created to route incoming requests to the backend service. Next, a target HTTP proxy is set up to handle HTTP requests using the URL map. A global forwarding rule listens on port 80 and directs client requests to the proxy. When a client sends a request, the CDN cache is checked. If the content is cached (cache hit), it is served immediately, providing fast response. If not cached (cache miss), the request goes to the backend service, which serves the content and caches it for future requests. This setup improves performance by serving content closer to users worldwide. Variables like backend service status, URL map, proxy, forwarding rule, cache status, and client response change step-by-step as the setup progresses and requests are handled.