ARM vs Bicep vs Terraform decision in Azure - Quick Revision & Key Differences

Recall & Review

beginner

What is ARM template in Azure?

ARM (Azure Resource Manager) template is a JSON file that defines the infrastructure and configuration for Azure resources. It is native to Azure and used to deploy resources declaratively.

beginner

What advantage does Bicep have over ARM templates?

Bicep is a simpler, more readable language that compiles into ARM templates. It reduces complexity and improves authoring experience while still being native to Azure.

intermediate

How does Terraform differ from ARM and Bicep?

Terraform is a cloud-agnostic tool that manages infrastructure across many providers, including Azure. It uses its own language (HCL) and state management, offering multi-cloud support.

intermediate

When should you choose ARM templates?

Choose ARM templates if you want native Azure support without extra tools and prefer JSON format. It is good for simple or existing Azure deployments.

intermediate

What is a key reason to pick Terraform over ARM or Bicep?

Pick Terraform if you need to manage infrastructure across multiple cloud providers or want a single tool for all environments.

Which tool compiles into ARM templates for Azure deployments?

A CloudFormation

B Terraform

C Bicep

D Ansible

Bicep is a domain-specific language that compiles into ARM templates for Azure.

Which tool is cloud-agnostic and supports multiple cloud providers?

A Bicep

B Terraform

C ARM templates

D Azure CLI

Terraform supports many cloud providers, making it cloud-agnostic.

What format do ARM templates use?

A JSON

B HCL

C YAML

D XML

ARM templates are written in JSON format.

Which tool offers the simplest syntax for Azure infrastructure as code?

A Bicep

B ARM templates

C PowerShell

D Terraform

Bicep provides a simpler, more readable syntax compared to ARM templates.

If you only manage Azure resources and want native support, which tool is best?

A Terraform

B ARM templates

C Bicep

D Chef

ARM templates and Bicep are both native to Azure and best for Azure-only deployments.

Explain the main differences between ARM templates, Bicep, and Terraform for Azure infrastructure deployment.

Think about language, cloud support, and ease of use.

Describe scenarios when you would choose Terraform over ARM or Bicep for managing Azure infrastructure.

Consider multi-cloud and tool consistency.

Practice

1. Which tool is native to Azure and uses JSON for defining infrastructure?

easy

A. Terraform

B. Bicep

C. ARM templates

D. Ansible

Solution

1. Step 1: Understand native Azure tools

   ARM templates are the original native infrastructure-as-code tool for Azure using JSON format.

2. Step 2: Compare with other tools

   Bicep simplifies ARM but is not JSON; Terraform is multi-cloud and not native Azure.

3. Final Answer:

   ARM templates -> Option C

4. Quick Check:

   Native Azure tool with JSON = ARM templates [OK]

Hint: Native Azure + JSON = ARM templates [OK]

Common Mistakes:

• Confusing Bicep as native JSON tool
• Thinking Terraform is Azure native
• Selecting Ansible which is not Azure native

2. Which syntax correctly declares a resource in Bicep?

easy

A. resource vm 'Microsoft.Compute/virtualMachines@2021-07-01' = { name: 'myVM' }

B.

C. resource "vm" { type = "Microsoft.Compute/virtualMachines" name = "myVM" }

D. vm_resource = { type: 'Microsoft.Compute/virtualMachines', name: 'myVM' }

Solution

1. Step 1: Identify Bicep syntax

   Bicep uses the keyword 'resource' followed by a symbolic name, type with API version, and properties in braces.

2. Step 2: Compare options

   resource vm 'Microsoft.Compute/virtualMachines@2021-07-01' = { name: 'myVM' } matches Bicep syntax; the XML-like syntax is invalid, the HCL-style block is Terraform syntax, and the plain object is invalid.

3. Final Answer:

   resource vm 'Microsoft.Compute/virtualMachines@2021-07-01' = { name: 'myVM' } -> Option A

4. Quick Check:

   Bicep resource syntax = resource vm 'Microsoft.Compute/virtualMachines@2021-07-01' = { name: 'myVM' } [OK]

Hint: Bicep uses 'resource name type@version = { }' syntax [OK]

Common Mistakes:

• Choosing Terraform syntax for Bicep
• Confusing ARM JSON/XML with Bicep
• Using invalid assignment formats

3. Given this Terraform snippet:

resource "azurerm_resource_group" "rg" {
  name     = "example-rg"
  location = "eastus"
}

What will happen when you run terraform apply?

medium

A. Deletes existing resource groups in East US

B. Fails because 'azurerm_resource_group' is invalid

C. Creates a virtual machine instead of a resource group

D. Creates a resource group named 'example-rg' in East US

Solution

1. Step 1: Understand Terraform resource block

   The block defines an Azure resource group named 'example-rg' in 'eastus' location.

2. Step 2: Predict Terraform apply behavior

   Terraform will create the resource group if it doesn't exist, no deletion or VM creation occurs.

3. Final Answer:

   Creates a resource group named 'example-rg' in East US -> Option D

4. Quick Check:

   Terraform resource block creates defined resource [OK]

Hint: Terraform resource block creates specified resource [OK]

Common Mistakes:

• Thinking resource type is invalid
• Confusing resource group with VM
• Assuming deletion happens automatically

4. You try to deploy an ARM template but get a syntax error. Which is the most likely cause?

medium

A. Missing resource group in Terraform provider

B. Using Bicep syntax directly in ARM JSON template

C. Incorrect API version in Bicep resource declaration

D. Using Terraform commands on ARM template

Solution

1. Step 1: Identify syntax error source

   ARM templates require JSON syntax; using Bicep syntax directly causes errors.

2. Step 2: Eliminate other options

   Missing resource group affects Terraform, not ARM JSON; API version errors in Bicep cause deployment errors but not syntax errors; Terraform commands on ARM templates cause command errors, not syntax errors.

3. Final Answer:

   Using Bicep syntax directly in ARM JSON template -> Option B

4. Quick Check:

   ARM JSON syntax error = Bicep syntax used wrongly [OK]

Hint: ARM templates need JSON, not Bicep syntax [OK]

Common Mistakes:

• Mixing Bicep syntax in ARM JSON
• Confusing deployment errors with syntax errors
• Assuming Terraform errors affect ARM templates

5. Your company uses Azure and AWS. You want a single tool to manage infrastructure on both clouds with reusable code. Which tool should you choose?

hard

A. Terraform

B. Bicep

C. Azure CLI scripts

D. ARM templates

Solution

1. Step 1: Identify multi-cloud support

   Terraform supports multiple cloud providers including Azure and AWS with reusable code modules.

2. Step 2: Compare other tools

   ARM and Bicep are Azure-only; Azure CLI scripts are Azure-specific and not declarative infrastructure code.

3. Final Answer:

   Terraform -> Option A

4. Quick Check:

   Multi-cloud infrastructure tool = Terraform [OK]

Hint: Terraform works across clouds, ARM/Bicep only Azure [OK]

Common Mistakes:

• Choosing ARM or Bicep for multi-cloud
• Thinking Azure CLI manages AWS
• Ignoring Terraform's multi-cloud strength