Create multiple web server instances with load balancing service in GCP

add-load-balancing.sh

#!/bin/sh

# Set default region and zone
gcloud config set compute/region europe-west1
gcloud config set compute/zone europe-west1-b

# Create a static IP address
gcloud compute addresses create network-lb-ip-1 \
  --region europe-west1

# Create a health check
gcloud compute http-health-checks create basic-check

# Create a target pool and add instances
gcloud compute target-pools create www-pool \
  --region europe-west1 --http-health-check basic-check

# Add instances to the target pool
gcloud compute target-pools add-instances www-pool \
    --instances web1,web2,web3

# Create a forwarding rule to route traffic to the target pool
gcloud compute forwarding-rules create www-rule \
    --region  europe-west1 \
    --ports 80 \
    --address network-lb-ip-1 \
    --target-pool www-pool

clear.sh

#!/bin/sh

# Set default region and zone
gcloud config set compute/region europe-west1
gcloud config set compute/zone europe-west1-b

# Cleanup resources
gcloud compute http-health-checks delete basic-check

gcloud compute addresses delete network-lb-ip-1 \
  --region europe-west1

gcloud compute firewall-rules delete www-firewall-network-lb

gcloud compute instances delete web1 --zone=europe-west1-b
gcloud compute instances delete web2 --zone=europe-west1-b
gcloud compute instances delete web3 --zone=europe-west1-b

create-multi-webserver.sh

#!/bin/sh

# Set default region and zone
gcloud config set compute/region europe-west1
gcloud config set compute/zone europe-west1-b

# Create three VM instances with Apache installed
gcloud compute instances create web1 \
    --zone=europe-west1-b \
    --tags=network-lb-tag \
    --machine-type=e2-small \
    --image-family=debian-12 \
    --image-project=debian-cloud \
    --metadata=startup-script='#!/bin/bash
      apt-get update
      apt-get install apache2 -y
      service apache2 restart
      echo "<h3>Web Server: web1</h3>" | tee /var/www/html/index.html'

gcloud compute instances create web2 \
    --zone=europe-west1-b \
    --tags=network-lb-tag \
    --machine-type=e2-small \
    --image-family=debian-12 \
    --image-project=debian-cloud \
    --metadata=startup-script='#!/bin/bash
      apt-get update
      apt-get install apache2 -y
      service apache2 restart
      echo "<h3>Web Server: web2</h3>" | tee /var/www/html/index.html'

gcloud compute instances create web3 \
    --zone=europe-west1-b \
    --tags=network-lb-tag \
    --machine-type=e2-small \
    --image-family=debian-12 \
    --image-project=debian-cloud \
    --metadata=startup-script='#!/bin/bash
      apt-get update
      apt-get install apache2 -y
      service apache2 restart
      echo "<h3>Web Server: web3</h3>" | tee /var/www/html/index.html'

# Create a firewall rule to allow HTTP traffic
gcloud compute firewall-rules create www-firewall-network-lb \
    --target-tags network-lb-tag --allow tcp:80

# Get the external IP address of the forwarding rule
gcloud compute instances list
curl http://[IP_ADDRESS]

you need to create three Compute Engine VM instances using the configuration that follows, install Apache on them, and then add a firewall rule www-firewall-network-lb that allows HTTP traffic to reach the instances.

Note: Make sure all the instances are under the default network.

1. Set the following values, leaving all others at their defaults:

Property	Value (type value or select option as specified)
VM Instance -1	web1
VM Instance -2	web2
VM Instance -3	web3
Region	europe-west1
Zone	europe-west1-b
Series	E2
Machine type	e2-small
Tags	network-lb-tag
image-family	debian-12
image-project	debian-cloud

Use the following script for installing Apache on each server (updating web-number such as web1 or web2 or web3 as per the instance's name):

#!/bin/bash
apt-get update
apt-get install apache2 -y
service apache2 restart
echo "<h3>Web Server: web-number</h3>" | tee /var/www/html/index.html

Note: You can verify that each instance is running with curl, replacing [IP_ADDRESS] with the IP address for each of your VMs:

curl http://[IP_ADDRESS]

If it doesn't work, try resetting the VM.

you need to create the resources that support the load balancing service.

1. Set the following values, leaving all others at their defaults:

Property	Value (type value or select option as specified)
Static external IP	network-lb-ip-1
Target-pool	www-pool
Ports	80

2. Once the load balancing service is configured, start sending traffic to the forwarding rule and watch the traffic be dispersed to different instances.