Azure Verified Modules (AVM) Requirements

This guide covers the mandatory requirements for Azure Verified Modules certification. These requirements ensure consistency, quality, and maintainability across Azure Terraform modules.

References:

Azure Verified Modules AVM Terraform Requirements Table of Contents Module Cross-Referencing Azure Provider Requirements Code Style Standards Variable Requirements Output Requirements Local Values Standards Terraform Configuration Requirements Testing Requirements Documentation Requirements Breaking Changes & Feature Management Contribution Standards Compliance Checklist Module Cross-Referencing

Severity: MUST | Requirement: TFFR1

When building Resource or Pattern modules, module owners MAY cross-reference other modules. However:

Modules MUST be referenced using HashiCorp Terraform registry reference to a pinned version Example: source = "Azure/xxx/azurerm" with version = "1.2.3" Modules MUST NOT use git references (e.g., git::https://xxx.yyy/xxx.git or github.com/xxx/yyy) Modules MUST NOT contain references to non-AVM modules Azure Provider Requirements

Severity: MUST | Requirement: TFFR3

Authors MUST only use the following Azure providers:

Provider Min Version Max Version azapi >= 2.0 < 3.0 azurerm >= 4.0 < 5.0

Requirements:

Authors MAY select either Azurerm, Azapi, or both providers MUST use required_providers block to enforce provider versions SHOULD use pessimistic version constraint operator (~>)

Example:

terraform { required_providers { azurerm = { source = "hashicorp/azurerm" version = "~> 4.0" } azapi = { source = "Azure/azapi" version = "~> 2.0" } } }

Code Style Standards Lower snake_casing

Severity: MUST | Requirement: TFNFR4

MUST use lower snake_casing for:

Locals Variables Outputs Resources (symbolic names) Modules (symbolic names)

Example: snake_casing_example

Resource & Data Source Ordering

Severity: SHOULD | Requirement: TFNFR6

Resources that are depended on SHOULD come first Resources with dependencies SHOULD be defined close to each other Count & for_each Usage

Severity: MUST | Requirement: TFNFR7

Use count for conditional resource creation MUST use map(xxx) or set(xxx) as resource's for_each collection The map's key or set's element MUST be static literals

Example:

resource "azurerm_subnet" "pair" { for_each = var.subnet_map # map(string) name = "${each.value}-pair" resource_group_name = azurerm_resource_group.example.name virtual_network_name = azurerm_virtual_network.example.name address_prefixes = ["10.0.1.0/24"] }

Resource & Data Block Internal Ordering

Severity: SHOULD | Requirement: TFNFR8

Order within resource/data blocks:

Meta-arguments (top):

provider count for_each

Arguments/blocks (middle, alphabetical):

Required arguments Optional arguments Required nested blocks Optional nested blocks

Meta-arguments (bottom):

depends_on lifecycle (with sub-order: create_before_destroy, ignore_changes, prevent_destroy)

Separate sections with blank lines.

Module Block Ordering

Severity: SHOULD | Requirement: TFNFR9

Order within module blocks:

Top meta-arguments:

source version count for_each

Arguments (alphabetical):

Required arguments Optional arguments

Bottom meta-arguments:

depends_on providers Lifecycle ignore_changes Syntax

Severity: MUST | Requirement: TFNFR10

The ignore_changes attribute MUST NOT be enclosed in double quotes.

Good:

lifecycle { ignore_changes = [tags] }

Bad:

lifecycle { ignore_changes = ["tags"] }

Null Comparison for Conditional Creation

Severity: SHOULD | Requirement: TFNFR11

For parameters requiring conditional resource creation, wrap with object type to avoid "known after apply" issues during plan stage.

Recommended:

variable "security_group" { type = object({ id = string }) default = null }

Dynamic Blocks for Optional Nested Objects

Severity: MUST | Requirement: TFNFR12

Nested blocks under conditions MUST use this pattern:

dynamic "identity" { for_each = ? [] : []

content { # block content } }

Default Values with coalesce/try

Severity: SHOULD | Requirement: TFNFR13

Good:

coalesce(var.new_network_security_group_name, "${var.subnet_name}-nsg")

Bad:

var.new_network_security_group_name == null ? "${var.subnet_name}-nsg" : var.new_network_security_group_name

Provider Declarations in Modules

Severity: MUST | Requirement: TFNFR27

provider MUST NOT be declared in modules (except for configuration_aliases) provider blocks in modules MUST only use alias Provider configurations SHOULD be passed in by module users Variable Requirements Not Allowed Variables

Severity: MUST | Requirement: TFNFR14

Module owners MUST NOT add variables like enabled or module_depends_on to control entire module operation. Boolean feature toggles for specific resources are acceptable.

Variable Definition Order

Severity: SHOULD | Requirement: TFNFR15

Variables SHOULD follow this order:

All required fields (alphabetical) All optional fields (alphabetical) Variable Naming Rules

Severity: SHOULD | Requirement: TFNFR16

Follow HashiCorp's naming rules Feature switches SHOULD use positive statements: xxx_enabled instead of xxx_disabled Variables with Descriptions

Severity: SHOULD | Requirement: TFNFR17

description SHOULD precisely describe the parameter's purpose and expected data type Target audience is module users, not developers For object types, use HEREDOC format Variables with Types

Severity: MUST | Requirement: TFNFR18

type MUST be defined for every variable type SHOULD be as precise as possible any MAY only be used with adequate reasons Use bool instead of string/number for true/false values Use concrete object instead of map(any) Sensitive Data Variables

Severity: SHOULD | Requirement: TFNFR19

If a variable's type is object and contains sensitive fields, the entire variable SHOULD be sensitive = true, or extract sensitive fields into separate variables.

Non-Nullable Defaults for Collections

Severity: SHOULD | Requirement: TFNFR20

Nullable SHOULD be set to false for collection values (sets, maps, lists) when using them in loops. For scalar values, null may have semantic meaning.

Discourage Nullability by Default

Severity: MUST | Requirement: TFNFR21

nullable = true MUST be avoided unless there's a specific semantic need for null values.

Avoid sensitive = false

Severity: MUST | Requirement: TFNFR22

sensitive = false MUST be avoided (this is the default).

Sensitive Default Value Conditions

Severity: MUST | Requirement: TFNFR23

A default value MUST NOT be set for sensitive inputs (e.g., default passwords).

Handling Deprecated Variables

Severity: MUST | Requirement: TFNFR24

Move deprecated variables to deprecated_variables.tf Annotate with DEPRECATED at the beginning of description Declare the replacement's name Clean up during major version releases Output Requirements Additional Terraform Outputs

Severity: SHOULD | Requirement: TFFR2

Authors SHOULD NOT output entire resource objects as these may contain sensitive data and the schema can change with API or provider versions.

Best Practices:

Output computed attributes of resources as discrete outputs (anti-corruption layer pattern) SHOULD NOT output values that are already inputs (except name) Use sensitive = true for sensitive attributes For resources deployed with for_each, output computed attributes in a map structure

Examples:

Single resource computed attribute

output "foo" { description = "MyResource foo attribute" value = azurerm_resource_myresource.foo }

for_each resources

output "childresource_foos" { description = "MyResource children's foo attributes" value = { for key, value in azurerm_resource_mychildresource : key => value.foo } }

Sensitive output

output "bar" { description = "MyResource bar attribute" value = azurerm_resource_myresource.bar sensitive = true }

Sensitive Data Outputs

Severity: MUST | Requirement: TFNFR29

Outputs containing confidential data MUST be declared with sensitive = true.

Handling Deprecated Outputs

Severity: MUST | Requirement: TFNFR30

Move deprecated outputs to deprecated_outputs.tf Define new outputs in outputs.tf Clean up during major version releases Local Values Standards locals.tf Organization

Severity: MAY | Requirement: TFNFR31

locals.tf SHOULD only contain locals blocks MAY declare locals blocks next to resources for advanced scenarios Alphabetical Local Arrangement

Severity: MUST | Requirement: TFNFR32

Expressions in locals blocks MUST be arranged alphabetically.

Precise Local Types

Severity: SHOULD | Requirement: TFNFR33

Use precise types (e.g., number for age, not string).

Terraform Configuration Requirements Terraform Version Requirements

Severity: MUST | Requirement: TFNFR25

terraform.tf requirements:

MUST contain only one terraform block First line MUST define required_version MUST include minimum version constraint MUST include maximum major version constraint SHOULD use ~> #.# or >= #.#.#, < #.#.# format

Example:

terraform { required_version = "~> 1.6" required_providers { azurerm = { source = "hashicorp/azurerm" version = "~> 4.0" } } }

Providers in required_providers

Severity: MUST | Requirement: TFNFR26

terraform block MUST contain required_providers block Each provider MUST specify source and version Providers SHOULD be sorted alphabetically Only include directly required providers source MUST be in format namespace/name version MUST include minimum and maximum major version constraints SHOULD use ~> #.# or >= #.#.#, < #.#.# format Testing Requirements Test Tooling

Severity: MUST | Requirement: TFNFR5

Required testing tools for AVM:

Terraform (terraform validate/fmt/test) terrafmt Checkov tflint (with azurerm ruleset) Go (optional for custom tests) Test Provider Configuration

Severity: SHOULD | Requirement: TFNFR36

For robust testing, prevent_deletion_if_contains_resources SHOULD be explicitly set to false in test provider configurations.

Documentation Requirements Module Documentation Generation

Severity: MUST | Requirement: TFNFR2

Documentation MUST be automatically generated via Terraform Docs A .terraform-docs.yml file MUST be present in the module root Breaking Changes & Feature Management Using Feature Toggles

Severity: MUST | Requirement: TFNFR34

New resources added in minor/patch versions MUST have a toggle variable to avoid creation by default:

variable "create_route_table" { type = bool default = false nullable = false }

resource "azurerm_route_table" "this" { count = var.create_route_table ? 1 : 0 # ... }

Reviewing Potential Breaking Changes

Severity: MUST | Requirement: TFNFR35

Breaking changes requiring caution:

Resource blocks:

Adding new resource without conditional creation Adding arguments with non-default values Adding nested blocks without dynamic Renaming resources without moved blocks Changing count to for_each or vice versa

Variable/Output blocks:

Deleting/renaming variables Changing variable type Changing variable default values Changing nullable to false Changing sensitive from false to true Adding variables without default Deleting outputs Changing output value Changing output sensitive value Contribution Standards GitHub Repository Branch Protection

Severity: MUST | Requirement: TFNFR3

Module owners MUST set branch protection policies on the default branch (typically main):

Require Pull Request before merging Require approval of most recent reviewable push Dismiss stale PR approvals when new commits are pushed Require linear history Prevent force pushes Not allow deletions Require CODEOWNERS review No bypassing settings allowed Enforce for administrators Compliance Checklist

Use this checklist when developing or reviewing Azure Verified Modules:

Module Structure Module cross-references use registry sources with pinned versions Azure providers (azurerm/azapi) versions meet AVM requirements .terraform-docs.yml present in module root CODEOWNERS file present Code Style All names use lower snake_casing Resources ordered with dependencies first for_each uses map() or set() with static keys Resource/data/module blocks follow proper internal ordering ignore_changes not quoted Dynamic blocks used for conditional nested objects coalesce() or try() used for default values Variables No enabled or module_depends_on variables Variables ordered: required (alphabetical) then optional (alphabetical) All variables have precise types (avoid any) All variables have descriptions Collections have nullable = false No sensitive = false declarations No default values for sensitive inputs Deprecated variables moved to deprecated_variables.tf Outputs Outputs use anti-corruption layer pattern (discrete attributes) Sensitive outputs marked sensitive = true Deprecated outputs moved to deprecated_outputs.tf Terraform Configuration terraform.tf has version constraints (~> format) required_providers block present with all providers No provider declarations in module (except aliases) Locals arranged alphabetically Testing & Quality Required testing tools configured New resources have feature toggles Breaking changes reviewed and documented Summary Statistics Functional Requirements: 3 Non-Functional Requirements: 34 Total Requirements: 37 By Severity MUST: 21 requirements SHOULD: 14 requirements MAY: 2 requirements

Based on: Azure Verified Modules - Terraform Requirements