GCloud

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