MPF utility (Azure Deployment Minimum Permissions Finder)

This utility finds the minimum permissions required for a given Azure deployment. This can help when you need to figure out the details of what permissions a service principal or managed identity will need to deploy a given ARM template, Bicep file, or Terraform module. Similarly, when assigning a Service Principal / Managed Identity to an Azure Policy Assignment, this utility can help you figure out the minimum permissions required by the Service Principal / Managed Identity to enforce/remediate the policy. It is recommended that the utility is used in a development or test environment to find the minimum permissions required.

How It Works

The overview of how this utility works is as follows:

• The key parameters the utility needs are the Service Principal details (Client ID, Secret, and Object ID) and details needed for the specific deployment provider:
  • ARM: ARM template file and parameters file needed
  • Terraform: Terraform module directory and variables file needed
• The utility removes any existing Role Assignments for the provided Service Principal
• A Custom Role (with no assigned permissions) is created
• The Service Principal (SP) is assigned the new custom role
• For the above steps, the utility uses the default Azure CLI credentials which need to have permissions to create custom roles and role assignments. The details of the permissions required by the default Azure CLI credentials are provided in the Permissions required by default Azure CLI credentials section.
• These sub-steps are retried until the deployment succeeds:
  • Depending on the provider (ARM, Bicep, or Terraform) a deployment is tried
  • If the Service Principal does not have sufficient permissions, an authorization error is returned by the deployment. If authorization errors have occurred, they are parsed to fetch the missing scopes and permissions. The authorizationErrorParser Tests provide details of the different kinds of authorization errors typically received.
  • The missing permissions are added to the custom role.
  • The missing permissions are added to the result.
• Once no authorization error is received, the utility prints the permissions assigned to the Service Principal.
• The required permissions are displayed based on the display options. These options can be used to view the resource-wise breakup of permissions and also to export the result in JSON format.
• All resources created are cleaned up by the utility, including the Role Assignments and Custom Role.

Supported Deployment Providers

• Azure ARM Template: The ARM endpoints of both modes described below return multiple authorization errors at a time, and as a result, the final output is usually displayed in under 90 seconds, even for complex templates.
  • What-if mode: This is the default ARM mode. It uses the ARM what-if endpoint to get the authorization errors and find the minimum permissions required for a deployment, without actually creating any resources.
  • FullDeployment mode: This mode has been deprecated and is no longer supported.
• Bicep: The Bicep mode is similar to the ARM what-if mode and uses the ARM what-if endpoint to get the authorization errors and find the minimum permissions required for a deployment, without actually creating any resources. Internally, the utility converts the Bicep file to an ARM template and then uses the ARM what-if endpoint.
• Terraform: The Terraform mode finds the minimum permissions required for a deployment by getting the authorization errors from the Terraform plan/apply and destroy commands. All resources are cleaned up by the utility. Since Terraform calls the ARM APIs for one resource at a time, the authorization errors are not received in bulk, and as a result, it can take quite long to get the final result. The overall time is the time taken to run the Terraform plan/apply/destroy commands, plus the overhead of getting and parsing the authorization errors a few times.

Flags and Environment Variables

The commands can be used with flags or environment variables. For details on the flags and environment variables, please refer to the command line flags and environment variables document.

Installation / Quickstart

For installation instructions, please refer to the installation and quickstart document.

Usage Details

For usage details, please refer to the quickstart / usage details document.

Display Options

To view details of the display options the utility provides, please refer to the display options document.

Building Locally

You can also build locally by cloning this repo and running make build.

Testing Locally

Unit Tests

To run the unit tests, run make test.

End to End ARM and Bicep Tests

To run the end-to-end tests for ARM and Bicep, you need to have the following environment variables set, and then execute make test-e2e:

export MPF_SUBSCRIPTIONID=YOUR_SUBSCRIPTION_ID
export MPF_TENANTID=YOUR_TENANT_ID
export MPF_SPCLIENTID=YOUR_SP_CLIENT_ID
export MPF_SPCLIENTSECRET=YOUR_SP_CLIENT_SECRET
export MPF_SPOBJECTID=YOUR_SP_OBJECT_ID
export MPF_BICEPEXECPATH="/opt/homebrew/bin/bicep" # Path to the Bicep executable

make test-e2e

End to End Terraform Tests

The Terraform end-to-end tests can take a long time to execute, depending on the resources being created. To run the end-to-end tests for Terraform, you need to have the following environment variables set, and then execute make test-e2e-terraform:

export MPF_SUBSCRIPTIONID=YOUR_SUBSCRIPTION_ID
export MPF_TENANTID=YOUR_TENANT_ID
export MPF_SPCLIENTID=YOUR_SP_CLIENT_ID
export MPF_SPCLIENTSECRET=YOUR_SP_CLIENT_SECRET
export MPF_SPOBJECTID=YOUR_SP_OBJECT_ID
export MPF_TFPATH=$(which terraform) # Path to the Terraform executable

make test-e2e-terraform

Permissions required by default Azure CLI credentials

The default Azure CLI credentials used by the utility need to have the following permissions:

• "Microsoft.Authorization/roleDefinitions/read"
• "Microsoft.Authorization/roleDefinitions/write"
• "Microsoft.Authorization/roleDefinitions/delete"
• "Microsoft.Authorization/roleAssignments/read"
• "Microsoft.Authorization/roleAssignments/write"
• "Microsoft.Authorization/roleAssignments/delete"
• "Microsoft.Resources/subscriptions/resourcegroups/delete"
• "Microsoft.Resources/subscriptions/resourcegroups/read"
• "Microsoft.Resources/subscriptions/resourcegroups/write"

Known Issues and Workarounds

The Known Issues and Workarounds document provides details on the known issues and workarounds for the utility.

MPF Design

The MPF Design document provides details on the design, including the packages and abstractions.

License

This project is under an MIT License.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

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This project has adopted the Microsoft Open Source Code of Conduct. For more information, see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.

Trademarks

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