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Part-29: 🚀 Google Cloud Compute Engine – Working with Disk Images


This content originally appeared on DEV Community and was authored by Latchu@DevOps

Google Cloud Compute Engine gives you several ways to create VM boot disks:

✅ Public Images (Linux, Windows, prebuilt images)

✅ Custom Images

✅ Snapshots

✅ Existing Disks

In this guide, we’ll focus on Disk Images – creating them from an existing VM, launching a new VM from that image, and finally managing deprecation & deletion.

🔹 Step 1: Introduction to Disk Images

An image is essentially a replica of a disk containing the OS and applications needed to boot a VM.

👉 Why use Images?

  • Consistency across multiple VMs
  • Faster provisioning with pre-installed apps
  • Reusable across projects & environments

We’ll:

  • Create a VM and install a webserver
  • Create a disk image from that VM
  • Launch a new VM from the image
  • Learn how to deprecate & delete images

🔹 Step 2: Explore Available Images

Go to:

👉 Compute Engine → Storage → Images

Here you’ll find:

  • Google-provided public images (Ubuntu, Debian, Windows, etc.)
  • Custom images you’ve created

🔹 Step 3: Create a VM Instance

We’ll create a VM (demo8-vm1) and install a simple NGINX webserver using a startup script.

Startup script (save as webserver-install.sh):

#!/bin/bash
sudo apt install -y telnet
sudo apt install -y nginx
sudo systemctl enable nginx
sudo chmod -R 755 /var/www/html
HOSTNAME=$(hostname)
sudo echo "<!DOCTYPE html> <html> <body style='background-color:rgb(250, 210, 210);'> <h1>Welcome to Latchu@DevOps - WebVM App1 </h1> <p><strong>VM Hostname:</strong> $HOSTNAME</p> <p><strong>VM IP Address:</strong> $(hostname -I)</p> <p><strong>Application Version:</strong> V1</p> <p>Google Cloud Platform - Demos</p> </body></html>" | sudo tee /var/www/html/index.html

Create VM with startup script:

gcloud compute instances create demo8-vm1 \
  --zone=us-central1-a \
  --machine-type=e2-micro \
  --network-interface=subnet=default \
  --tags=http-server \
  --metadata-from-file=startup-script=webserver-install.sh

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Access app in browser:

http://<external-ip-address>

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Stop VM (before creating image):

gcloud compute instances stop demo8-vm1 --zone=us-central1-a

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🔹 Step 4: Create Disk Image

We’ll now create a disk image from demo8-vm1.

Console:

  • Go to Compute Engine → Storage → Disks → demo8-vm1 → Actions → Create Image
  • Name: demo8-vm1-disk-image-v1
  • Source: Disk → demo8-vm1
  • Location: Multi-regional (US)
  • Family: mynginx-apps
  • Encryption: Google-managed key
  • Click on Create

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CLI:

gcloud compute images create demo8-vm1-disk-image-v1 \
    --project=gcpdemos \
    --family=mynginx-apps \
    --source-disk=demo8-vm1 \
    --source-disk-zone=us-central1-a \
    --storage-location=us

Verify:

gcloud compute images list --filter='name:demo8-vm1-disk-image-v1'

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🔹 Step 5: Review Disk Image Properties

  • Go to Compute Engine -> Storage -> Images -> demo8-vm1-disk-image-v1
  • Review Disk Image Properties

🔹Step-06: Create VM Instance from Disk Image

  • Go to Compute Engine -> Storage -> Images -> demo8-vm1-disk-image-v1
  • Click on CREATE INSTANCE
  • Name: demo8-vm2-from-disk-image
  • Labels: environment: dev
  • Region: us-central1
  • Zone: us-central1-a
  • Machine Family: 
Series: E2
Machine Type: e2-micro
  • Availability policies: 
VM provisioning model: Standard
  • Display Device: unchecked (leave to default)
  • Confidential VM Service: unchecked (leave to default)
  • Container: unchecked (leave to default)
  • Boot Disk: Custom Image 
Name: demo8-vm1-disk-image-v1
Boot Disk Type: New Balanced Persistent Disk
Size (GB): 10
Image: demo8-vm1-disk-image-v1
  • Identity and API Access: 
Service Account: Compute Engine default Service Account
Access Scopes: Allow default Access
  • Firewall 
Allow HTTP Traffic
  • Advanced Options: LEAVE TO DEFAULTS
  • Click on Create
  • KEY OBSERVATION: We didn’t pass any Startup Script here to install Webserver, but newly created VM instance will have the webserver. 
# Create VM Instance from a Disk Image
gcloud compute instances create demo8-vm2-from-disk-image \
    --project=gcpdemos \
    --zone=us-central1-a \
    --machine-type=e2-micro \
    --network-interface=subnet=default \
    --tags=http-server \
    --create-disk=image=projects/gcpdemos/global/images/demo8-vm1-disk-image-v1

Step-07: 🔹Verify newly created VM

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If you access the IP over the browser

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# Access Application
curl http://<EXTERNAL-IP-ADDRESS>
Observation: 
1. You will see the hostname will be as `demo8-vm1` in index.html even though hostnae of VM is `demo8-vm2-from-disk-image` because it is a disk clone from demo8-vm1 using Disk Image creation
2. This is just an observation to tell that we are using demo8-vm1 disk here from Disk Image

Step-08: 🔹 How to create new disk using Disk Image ?

  • Goto Storage -> Disks -> CREATE DISK
  • SOURCE: Image
  • SOURE IMAGE: demo8-vm1-disk-image-v1
  • Create and Verify Image list

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Step-09:🔹 Disk Image – Deprecate Option

  • Go to Compute Engine -> Storage -> Images -> demo8-vm1-disk-image-v1 -> Actions -> Deprecate

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Step-10:🔹 Disk Image – Delete Option

  • Go to Compute Engine -> Storage -> Images -> demo8-vm1-disk-image-v1 -> Select CHECK BOX
  • Click on DELETE

Step-11:🔹 Delete or Stop VM to avoid charges 

# Delete VM: demo8-vm2-from-disk-image
gcloud compute instances delete demo8-vm2-from-disk-image --zone=us-central1-a
gcloud compute instances list --filter='name:demo8-vm2-from-disk-image'

# Delete VM: demo8-vm1  (DONT DELETE WE WILL USE IN NEXT DEMO)
gcloud compute instances delete demo8-vm1 --zone=us-central1-a
gcloud compute instances list --filter='name:demo8-vm1'


This content originally appeared on DEV Community and was authored by Latchu@DevOps