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Validate Azure resource configuration#

PSRule makes it easy to validate Infrastructure as Code (IaC) such as Azure resources. For example, Azure resources can be validated to match an internal standard or baseline.


A pre-built module to validate Azure resources already exists. This scenario demonstrates the process and features of PSRule for illustration purposes.

Consider using or contributing these pre-built rule modules instead:

This scenario covers the following:

  • Defining a basic rule.
  • Adding a recommendation.
  • Using script pre-conditions.
  • Using helper functions.

In this scenario we will use a JSON file:

  • resources.json - An export for the Azure resource properties saved for offline use.

To generate a similar resources.json file of your own, the use following command.

# Get all resources using the Az modules. Alternatively use Get-AzureRmResource if using AzureRm modules.
# This command also requires authentication with Connect-AzAccount or Connect-AzureRmAccount
Get-AzResource -ExpandProperties | ConvertTo-Json -Depth 10 | Set-Content -path .\resources.json;

For this example we ran this command:

Get-AzResource -ExpandProperties | ConvertTo-Json -Depth 10 | Set-Content -path docs/scenarios/azure-resources/resources.json;

Define rules#

To validate our Azure resources we need to define some rules. Rules are defined by using the Rule keyword in a file ending with the .Rule.ps1 extension.

So start we are going to define a storageAccounts.UseHttps rule, which will validate that Azure Storage resources have a Secure Transfer Required enabled.

In the example below:

  • We use storageAccounts.UseHttps directly after the Rule keyword to name the rule definition. Each rule must be named uniquely.
  • The # Synopsis: comment is used to add additional metadata interpreted by PSRule.
  • One or more conditions are defined within the curly braces { }.
  • The rule definition is saved within a file named storageAccounts.Rule.ps1.
# Synopsis: Configure storage accounts to only accept encrypted traffic i.e. HTTPS/SMB
Rule 'storageAccounts.UseHttps' {
    # Rule conditions go here

Set rule condition#

Conditions can be any valid PowerShell expression that results in a $True or $False, just like an If statement, but without specifically requiring the If keyword to be used.

Several PSRule keywords such as Exists and AllOf can supplement PowerShell to quickly build out rules that are easy to read.

In resources.json one of our example storage accounts has a property Properties.supportsHttpsTrafficOnly as shown below, which will be how our rule will pass $True or fail $False Azure resources that we throw at it.

    "Name": "storage",
    "ResourceName": "storage",
    "ResourceType": "Microsoft.Storage/storageAccounts",
    "Kind": "Storage",
    "ResourceGroupName": "test-rg",
    "Location": "eastus2",
    "Properties": {
        "supportsHttpsTrafficOnly": false

In the example below:

  • We use the $TargetObject variable to get the object on the pipeline and access it's properties.
  • The condition will return $True or $False back to the pipeline, where:
    • $True - the object passed the validation check
    • $False - the object failed the validation check
# Synopsis: Configure storage accounts to only accept encrypted traffic i.e. HTTPS/SMB
Rule 'storageAccounts.UseHttps' {
    # This property returns true or false, so nothing more needs to be done

    # Alternatively this could be written as:
    # $TargetObject.Properties.supportsHttpsTrafficOnly -eq $True

Add rule recommendation#

Additionally to provide feedback to the person or process running the rules, we can use the Recommend keyword to set a message that appears in results.

If a recommend message is not provided the synopsis will be used instead.

In the example below:

  • Directly after the Recommend keyword is a message to help understand why the rule failed or passed.
# Synopsis: Configure storage accounts to only accept encrypted traffic i.e. HTTPS/SMB
Rule 'storageAccounts.UseHttps' {
    Recommend 'Storage accounts should only allow secure traffic'


Filter with preconditions#

So far our rule works for a Storage Account, but there are many type of resources that could be returned by calling Get-AzResource. Most of these resources won't have the Properties.supportsHttpsTrafficOnly property, and if it did, it may use different configuration options instead of just true and false. This is where preconditions help out.

Preconditions can be specified by using the -If parameter when defining a rule. When the rule is executed, if the precondition is $True then the rule is processed, otherwise it is skipped.

In the example below:

  • A check against $TargetObject.ResourceType ensured that our rule is only processed for Storage Accounts.
# Synopsis: Configure storage accounts to only accept encrypted traffic i.e. HTTPS/SMB
Rule 'storageAccounts.UseHttps' -If { $TargetObject.ResourceType -eq 'Microsoft.Storage/storageAccounts' } {
    Recommend 'Storage accounts should only allow secure traffic'


Skipped rules have the outcome None and are not included in output by default. To include skipped rules use the -Outcome All parameter.

Execute rules#

With a rule defined, the next step is to execute it. To execute rules, pipe the target object to Invoke-PSRule.

For example:

# Read resources in from file
$resources = Get-Content -Path .\resources.json | ConvertFrom-Json;

# Process resources
$resources | Invoke-PSRule;

PSRule natively supports reading from YAML and JSON files so this command-line can be simplified to:

Invoke-PSRule -InputPath .\resources.json;

You will notice, we didn't specify the rule. By default PSRule will look for any .Rule.ps1 files in the current working path.

Invoke-PSRule supports -Path, -Name and -Tag parameters that can be used to specify the path to look for rules in or filter rules if you want to run a subset of the rules.

For this example we ran these commands:

Invoke-PSRule -Path docs/scenarios/azure-resources -InputPath docs/scenarios/azure-resources/resources.json;

Our output looked like this:

   TargetName: storage

RuleName                            Outcome    Recommendation
--------                            -------    --------------
storageAccounts.UseHttps            Fail       Storage accounts should only allow secure traffic

In our case storageAccounts.UseHttps returns a Fail outcome because our storage account has supportsHttpsTrafficOnly = false, which is exactly what should happen.

Define helper functions#

Using helper functions is completely optional and not required in many cases. However, you may prefer to use helper functions when rule conditions or preconditions are complex and hard to understand.

To use helper functions use a function block within a file with a .Rule.ps1 extension. Any code within .Rule.ps1 files called by Invoke-PSRule will be executed, however to make it available for use within a rule, a global scope modifier must be used.

For functions this is done by prefixing the function name with global:.

For example:

function global:NameOfFunction {
    # Function body

In our example, we are going to define a ResourceType function in a file named common.Rule.ps1. This function will be used by preconditions to check the type of Azure resource.

# A custom function to filter by resource type
function global:ResourceType {
    param (

    process {
        return $TargetObject.ResourceType -eq $ResourceType;

Updating our existing storageAccounts.UseHttps rule, our rule definition becomes:

# Synopsis: Configure storage accounts to only accept encrypted traffic i.e. HTTPS/SMB
Rule 'storageAccounts.UseHttps' -If { ResourceType 'Microsoft.Storage/storageAccounts' } {
    Recommend 'Storage accounts should only allow secure traffic'


More information#