Allow Integer Parameter to Accept Null in a PowerShell Function

One of the great things about PowerShell being based on .NET is that we get to the huge number of types built into the framework.

A problem I came across today was that I needed to have a function that took a mandatory integer parameter, but that parameter needed to allow Null. In .NET there is a generic type System.Nullable<T> that allows other types to take on a null value.

This allows me to call the function above with the following:

Set-AdapterVlan -Adapter $adapter -Vlan $null

Which will clear the Vlan ID from the virtual network adapter.

The magic is in the parameter definition:

[Parameter(Mandatory = $true)]
[AllowNull()]
[Nullable[System.Int32]]
$VlanId

The [AllowNull()] attribute allows the $VlanId parameter to accept a Null even though it is mandatory, and the [Nullable[System.Int32]] allows $VlanId to be assigned a null value.

This isn’t something I use often, but thought it was worth sharing.

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Enable CORS Support in Cosmos DB using PowerShell

Support for Cross-Origin Resource Sharing (CORS) was recently added to Cosmos DB. If you want to enable CORS on an existing Cosmos DB account or create a new Cosmos DB account with CORS enabled it is very easy to do with Azure Resource Manager (ARM) templates or the Azure Portal.

But what if you’re wanting to find out the state of the CORS setting on an account or set it using PowerShell? Well, look no further.

The Cosmos DB PowerShell module (version 3.0.0 and above) supports creating Cosmos DB accounts with CORS enabled as well as updating and removing the CORS headers setting on an existing account. You can also retrieve the CORS setting for an existing Cosmos DB account.

Installing the CosmosDB Module

The first thing you need to do is install the CosmosDB PowerShell module from the PowerShell Gallery by running this in a PowerShell console:

ss_cosmosdbcors_installmodule

This will also install the Az PowerShell modules Az.Accounts and Az.Resources modules if they are not installed on your machine. The *-CosmosDbAccount functions in the CosmosDB module are dependent on these modules.

Note: The CosmosDB PowerShell module and the Az PowerShell modules are completely cross-platform and support Linux, MacOS and Windows. Running in either Windows PowerShell (Windows) or PowerShell Core (cross-platform) is supported.

Versions of the CosmosDB PowerShell module earlier than 3.0.0.0 use the older AzureRm/AzureRm.NetCore modules and do not support the CORS setting.

Authenticating to Azure with ‘Az’

Before using the CosmosDB PowerShell module accounts functions to work with CORS settings you’ll first need to authenticate to Azure using the Az PowerShell Modules. If you’re planning on automating this process you’ll want to authenticate to Azure using a Service Principal identity.

Side note: if you’re using this module in an Azure DevOps build/release pipeline the Azure PowerShell task will take care of the Service Principal authentication process for you:

ss_cosmosdbcors_azuredevopspowershelltask

But if you’re just doing a little bit of experimentation then you can just use an interactive authentication process.

To use the interactive authentication process just enter into your PowerShell console:

then follow the instructions.

ss_cosmosdbcors_authenticateaz.png

Create a Cosmos DB Account with CORS enabled

Once you have authenticated to Azure, you can use the New-CosmosDbAccount function to create a new account:

ss_cosmosdbcors_newcosmosdbaccountThis will create a new Cosmos DB account with the name dsrcosmosdbtest in the resource group dsrcosmosdbtest-rgp in the West US location and with CORS allowed origins of https://www.fabrikam.com and https://www.contoso.com.

Important: the New-CosmosDbAccount command assumes the resource group that is specified in the ResourceGroup parameter already exists and you have contributor access to it. If the resource group doesn’t exist then you can create it using the New-AzResourceGroup function or some other method.

It will take Azure a few minutes to create the new Cosmos DB account for you.

Side note: But if you want your PowerShell automation or script to be able to get on and do other tasks in the meantime, then add the -AsJob parameter to the New-CosmosDbAccountcall. This will cause the function to immediately return and provide you a Job object that you can use to periodically query the state of the Job. More information on using PowerShell Jobs can be found here.

Be aware, you won’t be able to use the Cosmos DB account until the Job is completed.

If you look in the Azure Portal, you will find the new Cosmos DB account with the CORS allowed origin values set as per your command:

ss_cosmosdbcors_cosmosdbinportalwithcors

Get the CORS Allowed Origins on a Cosmos DB Account

Getting the current CORS Allowed Origins value on an account is easy too. Just run the following PowerShell command:

ss_cosmosdbcors_getcosmosdbcors

This will return a string containing all the CORS Allowed Origins for the Cosmos DB account dsrcosmosdbtest.

You could easily split this string into an array variable by using:

ss_cosmosdbcors_getcosmosdbcorssplit

Update the CORS Allowed Origins on an existing Cosmos DB Account

To set the CORS Allowed Origins on an existing account use the Set-CosmosDbAccount function:

ss_cosmosdbcors_setcosmosdbcors

This will take a few minutes to update. So you can use the -AsJob parameter to run this as a Job.

Remove the CORS Allowed Origins from an existing Cosmos DB Account

You can remove the CORS Allowed Origins setting by setting using the Set-CosmosDbAccount function but passing in an empty string to the AllowedOrigin parameter:

ss_cosmosdbcors_removecosmosdbcors

This will take a few minutes to update as well. As always, you can use the -AsJob parameter to run this as a Job.

 

Final Words

Hopefully, you can see it is fairly simple to automate and work with the Cosmos DB CORS Allowed Origins setting using the PowerShell Cosmos DB module.

If you have any issues or queries or would like to contribute to the PowerShell Cosmos DB module, please head over to the GitHub repository.

 

Use Pester to Test Azure Resource Manager Templates for Best Practices

Recently I came across the amazing Secure DevOps Kit for Azure (AzSK). This contains a really useful AzSK PowerShell Module that contains cmdlets for performing different types of security scanning on Azure Resources, Subscriptions and Resource Manager Templates.

The feature of this module that I was most interested in for my current project was being able to scan ARM templates for best practice violations. The module contains several

To install the module, open a PowerShell Window and run:

Important: At the time of writing this post, the AzSK module has dependencies on the AzureRM.Profile and other AzureRM.* PowerShell modules. As of December 2018, the AzureRM.* PowerShell Modules are going to be renamed to Az.* (see this post). The AzureRM and Az modules can not be installed side-by-side, so if you’ve installed the Az PowerShell modules on your system then the installation of AzSK will fail because the AzureRM modules will also be installed and a conflict will occur.

The cmdlet we’re most interested in is the Get-AzSKARMTemplateSecurityStatus. It can be used to scan one or more ARM templates or entire folders of ARM templates for best practice violations:

ss_azsk_scanning

This will scan the ARM templates and produce a CSV report in a folder Microsoft\AzSKLogs\ARMChecker within your $ENV:LOCALAPPDATA folder and open the folder in Explorer. This isn’t ideal for automation scenarios or using during Continuous Integration or Continuous Delivery pipelines. I’ve raised an issue with the AzSK team on GitHub to see if this can be improved.

In my case, I wanted to be able to use the PowerShell Pester Module, a PowerShell testing framework, to execute tests on the output and then use the nUnit output Pester generates to publish into a Continuous Integration pipeline. To do that I needed to create a custom test script that would take the CSV report, count the failures of each level (High, Medium or Low) and fail if any are counted in the specific level.

This is what the script looks like:

You can download the script from GitHub Gist directly or get it from the PowerShell Gallery by running:

Install-Script -Name AzSKARMTemplateSecurityStatus.Test

To use it you will need to install Pester 4.3.0 and AzSK 3.6.1 modules:

Once that is done, you can use Invoke-Pester and pass in the TemplatePath and Severity parameters to the test script:

This will execute the Pester tests in the file above on the specified ARM template. The tests will fail when there are any best practice violations with the specified Severity or above. If you didn’t pass in a Severity then it will default to failing on Medium and High.

ss_azsk_invokepester

If you use the OutputFile and OutputFormat parameters to cause Pester to output an NUnit format file that most Continuous Integration tools will happily accept and use to display the output of the tests.

If you installed the script from the PowerShell Gallery, you can also run the tests like this:

AzSKARMTemplateSecurityStatus.Test -TemplatePath D:\101-webapp-basic-windows\azuredeploy.json

Finally, if you’re using Azure DevOps, you can also get this function as part Secure DevOps Kit (AzSK) CICD Extensions for Azure in the Azure DevOps Marketplace.

Which ever way you choose to consume AzSK, it is a great module and well worth including in your CI/CD pipelines to ensure your ARM templates meet best practices.

 

 

List Global Assembly Cache using PowerShell

The list of assemblies stored in the Global Assembly Cache (GAC) can be found in the registry under the HKEY_CLASSES_ROOT\Installer\Assemblies\Global key.

If you want to get a list of the assemblies registered in the GAC using PowerShell you can use this snippet:

ss_gac_getcontent

The first line registers a new drive called HKCR in PowerShell that maps to the HKEY_CLASSES_ROOT in the registry. This is required because, by default only the HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE registry hives are registered as drives in PowerShell.

The second line just gets the list of registry properties in the HKEY_CLASSES_ROOT\Installer\Assemblies\Global key and displays them.

 

 

Get the ForceChangePassword Office 365 User Setting with PowerShell

Recently I was asked by a friend if I knew of a way to get the value of the setting that forces a user to change their password when the next log in to Office 365. The friend wanted to get this value for all users using PowerShell.

Changing this setting is fairly straight forward either in the Office 365 portal or using the Set-MsolUserPassword cmdlet in the MSOnline PowerShell module:

ss_o365_setmsoluserpassword

However retrieving the current value of the setting isn’t possible using Get-MoslUser cmdlet – the attribute does not appear in the returned object:

ss_o365_getmsoluser

Instead, we need to use the Get-AzureADUser cmdlet in the AzureAD PowerShell Module to query the Azure Active Directory for the Office 365 tenant.

If you don’t have the AzureAD module installed, use Install-Module cmdlet to install it from the PowerShell Gallery:

Then connect to the AzureAD using the Connect-AzureAD cmdlet. Once connected you can run the following command to get the user object and show only the appropriate property (ForceChangePasswordNextLogin of the PasswordProfile object):

ss_o365_getazureadallforcechangepasswordnextlogin

This is all fairly straight forward once you figure out which object in Azure AD contains the information required.

Managing Users & Permissions in Cosmos DB with PowerShell

If you’re just getting started with Cosmos DB, you might not have come across users and permissions in a Cosmos DB database. However, there are certain use cases where managing users and permissions are necessary. For example, if you’re wanting to be able to limit access to a particular resource (e.g. a collection, document, stored procedure) by user.

The most common usage scenario for users and permissions is if you’re implementing a Resource Token Broker type pattern, allowing client applications to directly access the Cosmos DB database.

Side note: The Cosmos DB implementation of users and permissions only provides authorization – it does not provide authentication. It would be up to your own implementation to manage the authentication. In most cases you’d use something like Azure Active Directory to provide an authentication layer.

But if you go hunting through the Azure Management Portal Cosmos DB data explorer (or Azure Storage Explorer) you won’t find any way to configure or even view users and permissions.

ss_cdb_cosmosdbdataexplorer

To manage users and permissions you need to use the Cosmos DB API directly or one of the SDKs.

But to make Cosmos DB users and permissions easier to manage from PowerShell, I created the Cosmos DB PowerShell module. This is an open source project hosted on GitHub. The Cosmos DB module allows you to manage much more than just users and permissions, but for this post I just wanted to start with these.

Requirements

This module works on PowerShell 5.x and PowerShell Core 6.0.0. It probably works on PowerShell 3 and 4, but I don’t have any more machines running this version to test on.

The Cosmos DB module does not have any dependencies, except if you call the New-Cosmos DbContext function with the ResourceGroup parameter specified as this will use the AzureRM PowerShell modules to read the Master Key for the connection directly from your Cosmos DB account. So I’d recommend installing the Azure PowerShell modules or if you’re using PowerShell 6.0, install the AzureRM.NetCore modules.

Installing the Module

The best way to install the Cosmos DB PowerShell module is from the PowerShell Gallery. To install it for only your user account execute this PowerShell command:

Install-Module -Name CosmosDB -Scope CurrentUser

ss_cdb_cosmosdbinstallmodulecurrentuser

Or to install it for all users on the machine (requires administrator permissions):

Install-Module -Name CosmosDB

ss_cdb_cosmosdbinstallmoduleallusers

Context Variable

Update 2018-03-06

As of Cosmos DB module v2.0.1, the connection parameter has been renamed to context and the New-CosmosDbConnection function has been renamed New-CosmosDbContext. This was to be more inline with naming adopted by the Azure PowerShell project. The old connection parameters and New-CosmosDbConnection function is still available as an alias, so older scripts won’t break. But these should be changed to use the new naming if possible as I plan to deprecate the connection version at some point in the future.

This post was updated to specify the new naming, but screenshots still show the Connection aliases.

Before you get down to the process of working with Cosmos DB resources, you’ll need to create a context variable containing the information required to connect. This requires the following information:

  1. The Cosmos DB Account name
  2. The Cosmos DB Database name
  3. The Master Key for the account (you can have the Cosmos DB PowerShell module get this directly from your Azure account if you wish).

To create the connection variable we just use the New-CosmosDbContext:

ss_cdb_cosmosdbnewconnection

If you do not wish to specify your master key, you can have the New-CosmosDbContext function pull your master key from the Azure Management Portal directly:

ss_cdb_cosmosdbnewconnectionviaportal

Note: This requires the AzureRM.Profile and AzureRM.Resoures module on Windows PowerShell 5.x or AzureRM.Profile.NetCore and AzureRM.Resources.NetCore on PoweShell Core 6.0.0.

Managing Users

To add a user to the Cosmos DB Database use the New-CosmosDBUser function:

New-CosmosDbUser -Context $context -Id 'daniel'

ss_cdb_cosmosdbnewuser

To get a list of users in the database:

Get-CosmosDbUser -Context $context

ss_cdb_cosmosdbgetusers

To get a specific user:

Get-CosmosDbUser -Context $context -Id 'daniel'

ss_cdb_cosmosdbgetuser

To remove a user (this will also remove all permissions assigned to the user):

Remove-CosmosDbUser -Context $context -Id 'daniel'

ss_cdb_cosmosdbremoveuser

Managing Permissions

Permissions in Cosmos DB are granted to a user for a specific resource. For example, you could grant a user access to just a single document, an entire collection or to a stored procedure.

To grant a permission you need to provide four pieces of information:

  1. The Id of the user to grant the permission to.
  2. An Id for the permission to create. This is just string to uniquely identify the permission.
  3. The permission mode to the permission: All or Read.
  4. The Id of the resource to grant access to. This can be generated from one of the Get-CosmosDb*ResourcePath functions in the CosmosDB PowerShell module.

In the following example, we’ll grant the user daniel all access to the TestCollection:

ss_cdb_cosmosdbnewpermission

Once a permission has been granted, you can use the Get-CosmosDbPermission function to retrieve the permission and with it the Resource Token that can be used to access the resource for a limited amount of time (between 10 minutes and 5 hours).

Note: as you have the Master Key already, using the Resource Token isn’t required.

For example, to retrieve all permissions for the user with Id daniel and a resource token expiration of 600 seconds:

Get-CosmosDbPermission -Context $context -UserId 'daniel' -TokenExpiry '600' |
fl *

ss_cdb_cosmosdbgetpermission

You can as expected delete a permission by using the Remove-CosmosDbPermission function:

Remove-CosmosDbPermission -Context $context -UserId 'daniel' -Id 'AccessTestCollection'

ss_cdb_cosmosdbremovepermission

Final Thoughts

So this is pretty much all there is to managing users and permissions using the Cosmos DB PowerShell module. This module can also be used to manage the following Cosmos DB resources:

  • Attachments
  • Collections
  • Databases
  • Documents
  • Offers
  • Stored procedures
  • Triggers
  • User Defined Functions

You can find additional documentation and examples of how to manage these resources over in the Cosmos DB PowerShell module readme file on GitHub.

Hopefully this will help you in any Cosmos DB automation tasks you might need to implement.