GCloud

Overview

gcloud is the command-line interface for Google Cloud Platform (GCP) — it creates, configures, and scales resources like Compute Engine VMs, networks, and load balancers from a terminal or script. Every command follows a gcloud GROUP COMMAND structure (e.g. gcloud compute instances create).

This guide covers Compute Engine and building an HTTP load balancer with managed instance groups.

Information

GCloud Compute

• GCloud Compute Guide is still a work in progress; these are active notes from my current R&D.

  • shell gcloud compute --help
    • This will display all of the commands that will help you utilize the compute engine.

• The are split into two major concepts, with GROUP and COMMAND.

  • According to Google, the compute command helps create, configure and manipulate the virtual machines within your pre-set project.

  • The SYNOPSIS is gcloud compute GROUP | COMMAND [GCLOUD_WIDE_FLAG ...]

Load Balancer

Load balancing on the GCloud compuete platform.

• Command to run 3 instances of nginx with an ingress load balancer. Additional Documentation on Nginx Here

  • Shell command for VM that is running nginx inside of a debian operating system.

    •        gcloud compute instances create www-server-1 \
                --zone=us-west1-b \
                --tags=network-lb-tag \
                --machine-type=e2-medium \
                --image-family=debian-11 \
                --image-project=debian-cloud \
                --metadata=startup-script=start_nginx.sh

      • start_nginx.sh ->

        •                   #!/bin/bash
                            apt-get update
                            apt-get install nginx -y

      • For switching from Nginx to Apache2, replace the nginx with apache2.

      • To check the status on ubuntu, run the sudo systemctl status nginx OR sudo systemctl status apache2.

    • Example of a Load Balance Template:

      • The shell below is an example of an instance template that creates the load balance backend template.

        •     gcloud compute instance-templates create lb-backend-template \
              --region=us-west1 \
              --network=default \
              --subnet=default \
              --tags=allow-health-check \
              --machine-type=e2-medium \
              --image-family=debian-11 \
              --image-project=debian-cloud \
              --metadata=startup-script=start_nginx_script.sh

      • Key concept is : Managed instance groups MIGs

        • Mage instance groups or MIGs enable you to operate applications on multiple identical / clone virtual machines, thus allowing your orchestration to become scalable and highly available. This is done by utilizing the components within the automated MIG services, which includes: autoscaling, autohealing, regional (multiple zone) deployment, and automatic updating.

    • Manage Instance Group for the load balancer:

      •     gcloud compute instance-groups managed create lb-backend-group \
            --template=lb-backend-template --size=2 --zone=us-west1-b

      • 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
            ```

      • Backend-Services for gcloud compute

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

          • Add 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-west1-b \
                --global

          • Create a URL Map for routing the requests to the default backend services.

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

            • Extra information regarding the URL Map: Note: 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 Video go to one backend service. Requests for Audio go to a different backend service. Requests for 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:

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

            • 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

Google Rules

Google Forwarding Rules

Note: A forwarding rule and its corresponding IP address represent the frontend configuration of a Google Cloud load balancer. Learn more about the general understanding of forwarding rules from the Forwarding rule overview Guide.

Using Forwarding Rules Rule Concepts

FAQ

What is the gcloud CLI? gcloud is the command-line interface for Google Cloud Platform. It lets you create, configure, and scale resources — Compute Engine VMs, networks, load balancers, storage, and more — from a terminal or scripts. Commands follow a gcloud GROUP COMMAND structure.

How do I create a VM with gcloud? Use gcloud compute instances create NAME with flags for zone, machine type, and image, e.g. --zone=us-west1-b --machine-type=e2-medium --image-family=debian-11 --image-project=debian-cloud. A startup-script metadata flag can install software like Nginx on first boot.

What is a managed instance group (MIG)? A MIG runs multiple identical VMs from a single instance template. It provides autoscaling, autohealing, multi-zone deployment, and automatic rolling updates — the backend for scalable, highly available load-balanced applications.

How does an HTTP load balancer work on Google Cloud? An external HTTP load balancer chains a global forwarding rule and IP to a target HTTP proxy, which uses a URL map to route requests to backend services. Each backend service points at instance groups and a health check, so traffic only reaches healthy VMs.

What is a forwarding rule in Google Cloud? A forwarding rule and its IP address form the frontend of a load balancer. It matches incoming traffic on a protocol and port and forwards it to a target proxy or backend, tying the public entry point to the load balancing configuration behind it.