Why load balancing matters in GCP - Why It Works

Introduction

When many users visit a website or app at the same time, the servers can get overwhelmed and slow down or stop working. Load balancing helps by spreading the work evenly across multiple servers so everything runs smoothly and users get a fast response.

When your website gets many visitors at once and you want to avoid crashes.

When you run an app that needs to stay online all the time, even if one server fails.

When you want to improve the speed of your service by using multiple servers together.

When you want to add or remove servers without stopping your app.

When you want to make sure no single server gets too busy while others are idle.

Commands

This command creates a backend service that will manage traffic to your servers. It uses HTTP protocol and links to a health check to make sure servers are working.

Terminal

gcloud compute backend-services create my-backend-service --protocol HTTP --port-name http --health-checks my-health-check --global

Expected Output

Created [https://www.googleapis.com/compute/v1/projects/example-project/global/backendServices/my-backend-service].

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--protocol - Specifies the protocol used by the backend service.

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--health-checks - Links the backend service to a health check to monitor server health.

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--global - Creates a global backend service for global load balancing.

This command creates a URL map that directs incoming requests to the backend service you created.

Terminal

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

Expected Output

Created [https://www.googleapis.com/compute/v1/projects/example-project/global/urlMaps/my-url-map].

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--default-service - Sets the default backend service for all requests.

This command creates an HTTP proxy that uses the URL map to route traffic to your backend service.

Terminal

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

Expected Output

Created [https://www.googleapis.com/compute/v1/projects/example-project/global/targetHttpProxies/my-http-proxy].

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--url-map - Specifies the URL map the proxy will use.

This command creates a forwarding rule that listens on port 80 and sends traffic to the HTTP proxy, completing the load balancing setup.

Terminal

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

Expected Output

Created [https://www.googleapis.com/compute/v1/projects/example-project/global/forwardingRules/my-forwarding-rule].

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--global - Creates a global forwarding rule.

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--ports - Specifies the port to listen on for incoming traffic.

This command lists all backend services to verify that your load balancer backend service is created and active.

Terminal

gcloud compute backend-services list

Expected Output

NAME                 PROTOCOL  BACKENDS  HEALTH_CHECKS  TIMEOUT

my-backend-service   HTTP      0         my-health-check  30s

Key Concept

If you remember nothing else from this pattern, remember: load balancing spreads user traffic across servers to keep your app fast and reliable.

Common Mistakes

Not creating or linking a health check to the backend service.

Without health checks, the load balancer may send traffic to servers that are down, causing errors for users.

Always create a health check and link it to your backend service to monitor server health.

Forgetting to create a forwarding rule after setting up the backend service and proxy.

Without a forwarding rule, traffic will not reach your load balancer, so users cannot access your app.

Create a forwarding rule that listens on the correct port and points to your HTTP proxy.

Using regional instead of global flags when you want global load balancing.

Regional resources limit traffic to one region, missing the benefits of global load balancing.

Use the --global flag for backend services, forwarding rules, and proxies when setting up global load balancing.

Summary

Create a backend service with a health check to manage your servers.

Set up a URL map and HTTP proxy to route incoming traffic.

Create a forwarding rule to listen for user requests and send them to your proxy.

Verify your backend service is active to ensure load balancing works.