Stop 10 · Infrastructure as Code & AutomationTopics · 3/9

CloudFormation / ARM Templates / Deployment Manager

In short

Terraform works across clouds, but each big cloud also has its own built-in IaC tool. You'll meet them in job descriptions and in older company setups, so it's worth knowing how they think.

Each provider's native IaC tool — CloudFormation for AWS, ARM templates for Azure, Deployment Manager for GCP — deeply integrated with their respective platforms, at the cost of being locked to a single provider.

The blob character unrolls a blue house blueprint in front of a builder in a hard hat.

Think of it like this

Blueprint to the contractor

You hand the builder a full blueprint: rooms, wiring, plumbing. He builds exactly that. Want a bigger kitchen? You change the blueprint, not the walls. If a step fails midway, a good contractor undoes it rather than leave half a wall.

Watch it happen

A CloudFormation stack update

You

CloudFormation

AWS services

create-stack notes-dev

1/6You upload a template. CloudFormation works out the order: VPC before subnet, subnet before server.

The big ideas

What you need to know

AWS CloudFormation

YAML or JSON templates deployed as stacks. State is kept by AWS, so there's no state file to manage.

Azure ARM and Bicep

ARM templates are JSON. Bicep is Microsoft's shorter language that compiles to ARM, and most new Azure work uses it.

Google Cloud

Deployment Manager has been retired in favour of Infrastructure Manager, which runs Terraform for you.

Native vs Terraform

Native tools support new services on day one and need no state file. Terraform covers many clouds with one language.

See it in code

Walk through the code

yaml

1AWSTemplateFormatVersion: "2010-09-09"2Parameters:3  Env:4    Type: String5    AllowedValues: [dev, prod]6Resources:7  NotesBucket:8    Type: AWS::S3::Bucket9    Properties:10      VersioningConfiguration:11        Status: Enabled12      Tags:13        - { Key: env, Value: !Ref Env }14Outputs:15  BucketName:16    Value: !Ref NotesBucket

1/4A parameter, so one template serves dev and prod.

Deploy with: aws cloudformation deploy --template-file notes.yaml --stack-name notes-dev --parameter-overrides Env=dev

Save yourself the pain

Common mistakes

Oops

Editing a stack's resources by hand in the console after deploying it.

Do this instead

That causes drift. Change the template and update the stack. Use drift detection to spot manual edits.

Oops

Applying an update without looking at the change set.

Do this instead

Some property changes replace a resource, which can mean a new, empty database. Always read the preview.

Your mission

Stack it up, tear it down

~30 min

Quick check

A CloudFormation update fails halfway. What happens by default?

Go deeper

1Read a sample CloudFormation template (or your provider's equivalent) and identify its structure.
2Compare its syntax and workflow to Terraform's for the same simple resource.
3Learn why some teams prefer native tools for deep provider-specific feature support.