Boot disk images in GCP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

Boot Disk Image Selection Behavior

You create a new Compute Engine VM instance in Google Cloud Platform and specify a boot disk image family instead of a specific image version. What happens when the instance boots?

A The VM boots using the latest non-deprecated image from the specified image family.

B The VM boots using the oldest image available in the image family.

C The VM fails to boot because a specific image version is required.

D The VM boots using a random image from the image family.

💡 Hint

Think about how GCP manages image families to keep instances updated.

When you specify an image family, GCP automatically selects the latest non-deprecated image from that family to boot the VM. This ensures your VM uses the most recent stable image.

❓ Architecture

intermediate

Custom Boot Disk Image Usage

You want to create multiple VM instances with a custom boot disk image that includes pre-installed software. Which approach is best to ensure all instances use this custom image?

A Use the default public image and run a startup script to install software on each VM.

B Manually install the software on each new VM after creation.

C Create a custom image from a configured VM and specify this image as the boot disk for all new instances.

D Create snapshots of the boot disk after each VM is created.

💡 Hint

Consider how to reuse a configured disk image efficiently across multiple VMs.

Creating a custom image from a configured VM allows you to reuse that image as the boot disk for multiple instances, ensuring consistency and saving setup time.

❓ security

advanced

Securing Boot Disk Images

Which practice best enhances security when using boot disk images in Google Cloud Platform?

A Use only public images without modification to avoid configuration errors.

B Regularly update custom images with security patches before creating new instances.

C Disable encryption on boot disks to improve performance.

D Share boot disk images publicly to allow community review.

💡 Hint

Think about how to keep your VM images safe from vulnerabilities.

Regularly updating custom images with security patches ensures that new instances start with the latest protections, reducing exposure to known vulnerabilities.

❓ Configuration

advanced

Boot Disk Encryption Configuration

You want to create a VM instance with a boot disk encrypted using a customer-managed encryption key (CMEK). Which configuration step is required?

A Specify the CMEK key resource in the disk encryption key field when creating the boot disk.

B Encrypt the boot disk manually after the VM instance is created.

C Use the default Google-managed encryption key and then switch to CMEK later.

D Create the VM instance without encryption and enable CMEK in the instance settings.

💡 Hint

Consider how encryption keys are applied during disk creation.

To use CMEK for a boot disk, you must specify the customer-managed key during the disk creation process. This ensures the disk is encrypted with your key from the start.

✅ Best Practice

expert

Optimizing Boot Disk Image Management at Scale

Your organization manages hundreds of VM instances across multiple projects. You want to maintain consistent boot disk images and simplify updates. Which strategy best achieves this?

A Create custom images separately in each project to avoid cross-project dependencies.

B Use only public images and configure each VM with startup scripts for software installation.

C Manually update each VM instance's boot disk image individually when needed.

D Maintain a centralized custom image repository in a shared project and reference these images in all projects.

💡 Hint

Think about centralizing resources to improve consistency and ease management.

Centralizing custom images in a shared project allows all projects to use the same trusted images, simplifying updates and ensuring consistency across the organization.

Practice

1. What is the main purpose of a boot disk image in Google Cloud Platform (GCP)?

easy

A. It stores user data separately from the VM.

B. It provides the operating system for a virtual machine (VM).

C. It manages network traffic for the VM.

D. It controls billing and usage reports.

Solution

1. Step 1: Understand the role of boot disk images

   Boot disk images contain the operating system that a VM uses to start and run.

2. Step 2: Identify the correct function in GCP context

   In GCP, the boot disk image is the source of the OS for the VM instance.

3. Final Answer:

   It provides the operating system for a virtual machine (VM). -> Option B

4. Quick Check:

   Boot disk image = OS provider [OK]

Hint: Boot disk image = OS for VM startup [OK]

Common Mistakes:

• Confusing boot disk image with data disk
• Thinking it manages network or billing
• Assuming it stores user files

2. Which of the following is the correct command to list all available public boot disk images in GCP using gcloud CLI?

easy

A. gcloud compute images list --project=debian-cloud

B. gcloud compute instances list --images

C. gcloud compute disks list --public

D. gcloud compute images list --public

Solution

1. Step 1: Recall the correct gcloud command for listing images

   The command to list images uses 'gcloud compute images list' with a project filter for public images.

2. Step 2: Identify the public image project

   Public images like Debian are under projects such as 'debian-cloud'. So filtering by --project=debian-cloud lists those images.

3. Final Answer:

   gcloud compute images list --project=debian-cloud -> Option A

4. Quick Check:

   List images by project = gcloud compute images list --project=debian-cloud [OK]

Hint: Use --project with public image project name [OK]

Common Mistakes:

• Using --public flag which does not exist
• Listing disks instead of images
• Listing instances instead of images

3. Consider this snippet to create a VM with a boot disk image:

gcloud compute instances create my-vm \
--image-family=ubuntu-2204-lts \
--image-project=ubuntu-os-cloud

What OS will the VM run?

medium

A. Debian 10

B. CentOS 7

C. Ubuntu 22.04 LTS

D. Windows Server 2019

Solution

1. Step 1: Analyze the image family and project

   The image family 'ubuntu-2204-lts' in project 'ubuntu-os-cloud' refers to Ubuntu 22.04 Long Term Support.

2. Step 2: Match image family to OS version

   Ubuntu 22.04 LTS is the latest stable Ubuntu release matching the image family name.

3. Final Answer:

   Ubuntu 22.04 LTS -> Option C

4. Quick Check:

   Image family ubuntu-2204-lts = Ubuntu 22.04 LTS [OK]

Hint: Image family name shows OS version clearly [OK]

Common Mistakes:

• Confusing Ubuntu with Debian or CentOS
• Ignoring image-project parameter
• Assuming Windows from Linux image family

4. You tried to create a VM with this command:

gcloud compute instances create test-vm \
--image-family=centos-7 \
--image-project=centos-cloud \
--boot-disk-size=5GB

The command fails with an error about disk size. What is the likely cause?

medium

A. The VM name 'test-vm' is invalid.

B. The image family name is incorrect.

C. The project name 'centos-cloud' does not exist.

D. The boot disk size is too small for the CentOS 7 image.

Solution

1. Step 1: Understand boot disk size requirements

   CentOS 7 images require a minimum boot disk size larger than 5GB, usually 10GB or more.

2. Step 2: Check command parameters

   The image family and project are correct, and VM name is valid, so the error is due to insufficient disk size.

3. Final Answer:

   The boot disk size is too small for the CentOS 7 image. -> Option D

4. Quick Check:

   Disk size too small causes boot failure [OK]

Hint: Check minimum disk size for image before creating VM [OK]

Common Mistakes:

• Assuming image family or project is wrong
• Ignoring disk size minimum requirements
• Thinking VM name causes disk size error

5. You want to create a custom boot disk image from an existing VM's disk to use for multiple new VMs. Which steps should you follow?

hard

A. Create a snapshot of the VM's boot disk, then create an image from the snapshot.

B. Directly copy the VM instance to create new VMs without images.

C. Export the VM's disk to a local file, then upload it as an image.

D. Create a new VM and select the existing VM's disk as boot disk.

Solution

1. Step 1: Create a snapshot of the existing VM's boot disk

   This captures the current state of the disk safely and efficiently.

2. Step 2: Create a custom image from the snapshot

   Using the snapshot, you create a reusable boot disk image for new VMs.

3. Final Answer:

   Create a snapshot of the VM's boot disk, then create an image from the snapshot. -> Option A

4. Quick Check:

   Snapshot then image = reusable boot disk [OK]

Hint: Snapshot first, then create image for reuse [OK]

Common Mistakes:

• Trying to copy VM directly without image
• Exporting disk unnecessarily
• Using existing disk directly for new VMs