Instance templates in GCP - Step-by-Step Execution

Process Flow - Instance templates

Create Instance Template

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Define VM Settings

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Save Template

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Use Template to Create VMs

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VMs Launch with Template Settings

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Manage or Update Template

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Apply Updated Template to New VMs

You create an instance template by defining VM settings, save it, then use it to launch multiple VMs with the same configuration.

Execution Sample

GCP

gcloud compute instance-templates create my-template \
  --machine-type=e2-medium \
  --image-family=debian-11 \
  --image-project=debian-cloud

This command creates an instance template named 'my-template' with a specific machine type and Debian image.

Process Table

Step	Action	Input/Command	Result/State
1	Start creating instance template	gcloud compute instance-templates create my-template	Template creation initiated
2	Set machine type	--machine-type=e2-medium	Machine type set to e2-medium
3	Set image family and project	--image-family=debian-11 --image-project=debian-cloud	Image set to Debian 11 from debian-cloud project
4	Save template	Command execution completes	Instance template 'my-template' created and saved
5	Use template to create VM	gcloud compute instances create vm-1 --source-instance-template=my-template	VM 'vm-1' created with template settings
6	Verify VM settings	Check VM machine type and image	VM 'vm-1' has e2-medium machine and Debian 11 image
7	Update template (optional)	Create new template or modify settings	New or updated template ready for future VMs
8	Exit	No further commands	Process complete

💡 All steps completed; instance template created and used to launch VM

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	Final
Template Name	None	my-template	my-template	my-template	my-template	my-template
Machine Type	None	e2-medium	e2-medium	e2-medium	e2-medium	e2-medium
Image	None	None	debian-11 (debian-cloud)	debian-11 (debian-cloud)	debian-11 (debian-cloud)	debian-11 (debian-cloud)
VM Created	No	No	No	No	Yes (vm-1)	Yes (vm-1)

Key Moments - 3 Insights

Why do we create an instance template instead of configuring each VM manually?

Instance templates let you define VM settings once and reuse them, saving time and ensuring consistency, as shown in steps 1-5 of the execution table.

Can we change the settings of an existing instance template after creation?

No, instance templates are immutable. To change settings, create a new template as indicated in step 7.

What happens if we launch a VM without specifying an instance template?

You must manually specify all VM settings. Using a template automates this, as shown in step 5 where the VM inherits template settings.

Visual Quiz - 3 Questions

Look at the execution table, what machine type is set after step 2?

A e2-small

B n1-standard-1

C e2-medium

D custom

💡 Hint

Check the 'Machine Type' variable in variable_tracker after Step 2

At which step is the VM 'vm-1' created using the instance template?

A Step 5

B Step 3

C Step 7

D Step 2

💡 Hint

Look for 'VM Created' status change in variable_tracker and 'Use template to create VM' in execution_table

If you want to change the VM image for future VMs, what should you do according to the execution flow?

A Update the VM after creation

B Create a new instance template with the new image

C Modify the existing instance template directly

D Delete the VM and recreate it

💡 Hint

Refer to step 7 in execution_table and key_moments about template immutability

Concept Snapshot

Instance templates define VM settings once
They include machine type, image, and other configs
Templates are immutable after creation
Use templates to launch consistent VMs quickly
Update by creating new templates
Simplifies VM management at scale

Full Transcript

Instance templates in Google Cloud let you save VM configurations like machine type and image in one reusable template. You start by creating a template with commands specifying these settings. Once saved, you can launch multiple VMs using this template, ensuring they all have the same setup. Templates cannot be changed after creation; to update settings, you create a new template. This process saves time and keeps VM setups consistent across your cloud environment.