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Validate Azure resources from templates with Azure Pipelines#

Azure Resource Manager (ARM) templates are a JSON-based file structure. ARM templates are typically not static, they include parameters, functions and conditions. Depending on the parameters provided to a template, resources may differ significantly.

Important resource properties that should be validated are often variables, parameters or deployed conditionally. Under these circumstances, to correctly validate resources in a template, parameters must be resolved.

The following scenario shows how PSRule can be used to validate Azure resource templates within an Azure Pipeline.

This scenario covers the following:

Installing PSRule extension#

PSRule includes an extension that can be installed from the Visual Studio Marketplace. Once installed, Azure Pipelines tasks are available to install PSRule modules and run analysis.

Linking parameter files to templates#

ARM template parameter files allows parameters for a deployment to be saved and checked into source control. PSRule can automatically resolve ARM templates from parameter files by using a metadata link.

To link a parameter file to an ARM template add the metadata.template property within a parameter file.

For example:

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
    "contentVersion": "1.0.0.0",
    "metadata": {
        "template": "./azuredeploy.json"
    },
    "parameters": {
        "vnetName": {
            "value": "vnet-001"
        },
        "addressPrefix": {
            "value": [
                "10.1.0.0/24"
            ]
        }
    }
}

In the example parameter file azuredeploy.parameters.json is linked to the template azuredeploy.json. The prefix of ./ indicates that the template file is in a relative path to the parameter file. If ./ is not included, PSRule will look for the template relative to the working directory.

For example:

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
    "contentVersion": "1.0.0.0",
    "metadata": {
        "template": "templates/vnet-hub/v1/template.json"
    },
    "parameters": {
        "vnetName": {
            "value": "vnet-001"
        },
        "addressPrefix": {
            "value": [
                "10.1.0.0/24"
            ]
        }
    }
}

Creating a YAML pipeline#

Azure Pipelines supports defining pipelines in YAML. PSRule uses a number of configurable task steps to install modules, export data and perform analysis.

Installing Azure rules#

To install the module containing Azure rules use the ps-rule-install YAML task.

# Install PSRule.Rules.Azure from the PowerShell Gallery.
- task: ps-rule-install@1
  inputs:
    module: PSRule.Rules.Azure   # Install PSRule.Rules.Azure from the PowerShell Gallery.

Exporting resource data for analysis#

PSRule provides a pre-built cmdlets for finding template files within a path and exporting resource data.

  • Get-AzRuleTemplateLink finds linked templates from parameter files. By default, parameter files with the *.parameters.json extension are discovered. Files are found recursively from the current working path.
  • Export-AzRuleTemplateData exports resource data from template files.

To generate data for analysis use a PowerShell YAML task to export resource data from linked templates.

# Export resource data from parameter files within the current working directory.
- powershell: Get-AzRuleTemplateLink | Export-AzRuleTemplateData -OutputPath out/templates/;
  displayName: 'Export template data'

If parameter files are located in a specific sub-directory the path can be updated as follows.

# Export resource data from parameter files in the deployments/ sub-directory.
- powershell: Get-AzRuleTemplateLink ./deployments/ | Export-AzRuleTemplateData -OutputPath out/templates/;
  displayName: 'Export template data'

If parameter files do not use the file extension .parameters.json input path can be set.

# Export resource data from parameter files ending in *.json instead of default *.parameters.json.
- powershell: Get-AzRuleTemplateLink -InputPath *.json | Export-AzRuleTemplateData -OutputPath out/templates/;
  displayName: 'Export template data'

In both cases, resource data for analysis is exported to out/templates/.

Validating exported resources#

To validate exported resources use the ps-rule-assert YAML task. The following task uses previously exported resource data for analysis.

# Run analysis from JSON files using the `PSRule.Rules.Azure` module and custom rules from `.ps-rule/`.
- task: ps-rule-assert@1
  inputs:
    inputType: inputPath
    inputPath: 'out/templates/*.json'        # Read exported resource data from 'out/templates/'.
    modules: 'PSRule.Rules.Azure'            # Analyze objects using the rules within the PSRule.Rules.Azure PowerShell module.
    # Optionally, also analyze objects using custom rules from '.ps-rule/'.
    source: '.ps-rule/'
    # Optionally, save results to an NUnit report.
    outputFormat: NUnit3
    outputPath: reports/ps-rule-resources.xml

In the example:

  • Resource data is read from out/templates/.
  • If custom rules are defined in the .ps-rule/ these are also evaluated.
  • Validation results are saved as an NUnit report.

Generating NUnit output#

NUnit is a popular unit test framework for .NET. PSRule supports publishing validation results in the NUnit format. With Azure DevOps, an NUnit report can be published using Publish Test Results task.

An example YAML snippet is included below:

# Publish NUnit report as test results
- task: PublishTestResults@2
  displayName: 'Publish PSRule results'
  inputs:
    testRunTitle: 'PSRule'                          # The title to use for the test run.
    testRunner: NUnit                               # Import report using the NUnit format.
    testResultsFiles: 'reports/ps-rule-results.xml' # The previously saved NUnit report.
  condition: succeededOrFailed()                    # Run this task if previous steps succeeded of failed.

Complete example#

Putting each of these steps together.

Azure DevOps Pipeline#

#
# PSRule with Azure Pipelines
#

trigger:
- main

pool:
  vmImage: 'ubuntu-latest'

steps:

# Install PSRule.Rules.Azure from the PowerShell Gallery
- task: ps-rule-install@1
  inputs:
    module: PSRule.Rules.Azure   # Install PSRule.Rules.Azure from the PowerShell Gallery.

# Export resource data from parameter files within the current working directory.
- powershell: Get-AzRuleTemplateLink | Export-AzRuleTemplateData -OutputPath out/templates/;
  displayName: 'Export template data'

# Run analysis from JSON files using the `PSRule.Rules.Azure` module and custom rules from `.ps-rule/`.
- task: ps-rule-assert@1
  inputs:
    inputType: inputPath
    inputPath: 'out/templates/*.json'        # Read exported resource data from 'out/templates/'.
    modules: 'PSRule.Rules.Azure'            # Analyze objects using the rules within the PSRule.Rules.Azure PowerShell module.
    # Optionally, also analyze objects using custom rules from '.ps-rule/'.
    source: '.ps-rule/'
    # Optionally, save results to an NUnit report.
    outputFormat: NUnit3
    outputPath: reports/ps-rule-resources.xml

# Publish NUnit report as test results
- task: PublishTestResults@2
  displayName: 'Publish PSRule results'
  inputs:
    testRunTitle: 'PSRule'                          # The title to use for the test run.
    testRunner: NUnit                               # Import report using the NUnit format.
    testResultsFiles: 'reports/ps-rule-*.xml'       # Use previously saved NUnit reports.
    mergeTestResults: true                          # Merge multiple reports.
  condition: succeededOrFailed()                    # Run this task if previous steps succeeded of failed.

More information#


Last update: 2022-01-07