GCP HTTP(S) Load Balancer - ghdrako/doc_snipets GitHub Wiki

HTTP(S) Load Balancing is implemented on Google Front End (GFE). GFEs are distributed globally and operate together using Google's global network and control plane. You can configure URL rules to route some URLs to one set of instances and route other URLs to other instances. Requests are always routed to the instance group that is closest to the user, if that group has enough capacity and is appropriate for the request. If the closest group does not have enough capacity, the request is sent to the closest group that does have capacity.

To set up a load balancer with a Compute Engine backend, your VMs need to be in an instance group. The managed instance group provides VMs running the backend servers of an external HTTP load balancer.

create the load balancer template

gcloud compute instance-templates create lb-backend-template \
   --region=us-central1 \
   --network=default \
   --subnet=default \
   --tags=allow-health-check \
   --image-family=debian-9 \
   --image-project=debian-cloud \
   --metadata=startup-script='#! /bin/bash
     apt-get update
     apt-get install apache2 -y
     a2ensite default-ssl
     a2enmod ssl
     vm_hostname="$(curl -H "Metadata-Flavor:Google" \
     http://169.254.169.254/computeMetadata/v1/instance/name)"
     echo "Page served from: $vm_hostname" | \
     tee /var/www/html/index.html
     systemctl restart apache2'

Create a managed instance groups (MIGs) based on the template:

gcloud compute instance-groups managed create lb-backend-group \
   --template=lb-backend-template --size=2 --zone=us-central1-a

Create the fw-allow-health-check firewall rule. This is an ingress rule that allows traffic from the Google Cloud health checking systems (130.211.0.0/22 and 35.191.0.0/16). To identify the VMs uses the target tag allow-health-check

gcloud compute firewall-rules create fw-allow-health-check \
    --network=default \
    --action=allow \
    --direction=ingress \
    --source-ranges=130.211.0.0/22,35.191.0.0/16 \
    --target-tags=allow-health-check \
    --rules=tcp:80

set up a global static external IP address that use to reach your load balancer.

gcloud compute addresses create lb-ipv4-1 \
    --ip-version=IPV4 \
    --global

Show IPv4 address that was reserved

gcloud compute addresses describe lb-ipv4-1 \
    --format="get(address)" \
    --global

Create a health check for the load balancer:

gcloud compute health-checks create http http-basic-check \
    --port 80

Create a backend service:

gcloud compute backend-services create web-backend-service \
    --protocol=HTTP \
    --port-name=http \
    --health-checks=http-basic-check \
    --global

Add your instance group as the backend to the backend service:

gcloud compute backend-services add-backend web-backend-service \
    --instance-group=lb-backend-group \
    --instance-group-zone=us-central1-a \
    --global

Create a URL map to route the incoming requests to the default backend service

gcloud compute url-maps create web-map-http \
    --default-service web-backend-service

URL map is a Google Cloud configuration resource used to route requests to backend services or backend buckets. For example, with an external HTTP(S) load balancer, you can use a single URL map to route requests to different destinations based on the rules configured in the URL map:

Requests for https://example.com/video go to one backend service.
Requests for https://example.com/audio go to a different backend service.
Requests for https://example.com/images go to a Cloud Storage backend bucket.
Requests for any other host and path combination go to a default backend service.

Create a target HTTP proxy to route requests to your URL map:

gcloud compute target-http-proxies create http-lb-proxy \
    --url-map web-map-http

Create a global forwarding rule to route incoming requests to the proxy:

gcloud compute forwarding-rules create http-content-rule \
    --address=lb-ipv4-1\
    --global \
    --target-http-proxy=http-lb-proxy \
    --ports=80

A forwarding rule and its corresponding IP address represent the frontend configuration of a Google Cloud load balancer. For a general understanding of forwarding rules, see Forwarding rule concepts.

11 When the VMs are healthy in Load Balancing Backend section , test the load balancer using a web browser, going to http://IP_ADDRESS/, replacing IP_ADDRESS with the load balancer's IP address.