Rotating Event Hubs RP External Certificate on Azure Stack Hub

I have been testing the Event Hubs public preview release for Azure Stack Hub, looking at the install process and what kind of actions an Operator would need to do to keep things running. One of the important ones for me, are rotating secrets / certificates. If your certificates expire, you won’t be able to access the RP, hence the importance.

If you check the current documentation for rotating secrets , it is the generic instructions for rotating external certificates for the Azure Stack Hub Stamp. I expect that this will be corrected in the near future, but until then , how do you do go about it for the Public Preview?

Firstly, you need the latest version of the Azure Stack Hub PowerShell modules:

• AzureRM compatible module

• Az compatible module

Then you need to connect to your Azure Stack Hub Admin environment. Use the steps detailed in the following article : https://docs.microsoft.com/en-us/azure-stack/operator/azure-stack-powershell-configure-admin?view=azs-2002

(Remember if using the Az Module to rename the Commands per https://docs.microsoft.com/en-us/azure-stack/operator/powershell-install-az-module?view=azs-2002#7-use-the-az-module)

Copy the Event Hubs pfx file to a local directory and run the following script (The example is using theAz module)t:

$ProductId = 'microsoft.eventhub'
$productVersion = (Get-AzsProductDeployment -ProductId microsoft.eventhub).properties.deployment.version
$PackageId = ('{0}.{1}' -f $ProductId, $productVersion)
$packageSecret = ((Get-AzsProductSecret -PackageId $PackageId).value.name).split('/')[2]
$certPath = 'C:\AzsCerts\EventHubs\cert.pfx'

$pfxPassword = (ConvertTo-SecureString '<pfxPassword>' -AsPlainText -Force)
Set-AzsProductSecret -PackageId $PackageId -SecretName $packageSecret -PfxFileName $certPath  -PfxPassword $pfxPassword -Force -Verbose

Invoke-AzsProductRotateSecretsAction -ProductId $ProductId

Modify the $certPath variable and <pfxPassword> to match what you have set and then run the script.

The process will take quite a long time to complete. Whilst the operation is taking place, you will receive the status of the command.

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If you choose to stop the CmdLet/script, the process will continue in the background. You can check the status at anytime by running the following:

(Get-AzsProductDeployment -ProductId microsoft.eventhub).properties

You should see something like this when the process is still running:

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… and when successfully finished:

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Hope that helps until the official documentation is released!

Article updated 16 July 2020 with an updated method to obtain the secret name, provided by @kongou_ae - Thanks!

Generate Azure Stack Hub Certificates using an Enterprise CA - the automated way

Anyone who has had to deploy or operate Azure Stack Hub will tell you that one of the most laborious and tricky tasks is the generation of PKI certificates for the external endpoints. There are quite stringent requirements that can be found here.

I have already written about and created a script that can be used to generate Lets Encrypt signed certificates, but that doesn’t meet everyone’s requirements.

A common scenario is to use a Certificate Authority hosted on Windows Server. Here are the high level tasks that need to be carried out:

1. Generate the requests

2. Submit the request to the CA

3. Approve the request

4. Retrieve the signed cert

5. Import the signed cert

6. Export the certificate as a Pfx file with password

7. Place the exported Pfx files into specific folders for use by Azure Stack Hub

8. Test the certs for validity

Microsoft have helped by creating the Azure Stack Readiness Checker PowerShell module, which really is a great tool for generating the certificate requests and checking the validity of the Pfx files, but we need a process to automate all of the steps above.

To help with that, I’ve created a script that will take some inputs and do the rest for you. You can find it here.

The main script is New-AzsHubCertificates.ps1. It takes the following parameters:

Parameter	Type	Description
azsregion	String	Azure Stack Hub Region Name
azsCertDir	String	Directory to store certificates
CaServer	String	IP address fo the Certificate Authority Server
IdentitySystem	String	Either AAD or ADFS
CaCredential	Credential	Credentials to connect to the Certificate Authority Server
AppServer	Boolean	Choose if App Service Certs should be generated
DBAdapter	Boolean	Choose if DB Adapter Cert should be generated
EventHubs	Boolean	Choose if Event Hubs Cert should be generated
IoTHubs	Boolean	Choose if IOT Hub Cert should be generated
SkipDeployment	Boolean	Choose if you do not require the deployment certificates generating
pfxPassword	SecureString	Password for the Pfx Files

It utilizes the Azure Stack Readiness Checker module to generate the cert requests and to also validate that the certificates are fit for purpose, so ensure that you have the module installed. The script also needs to be run from an elevated session as it needs to import and export certificates from the Computer store that you run it from (needless to say you need to run it from a Windows client :) ).

1. The first thing the script does is create the folder for the certificates. It takes the input you specify and will create a sub-folder from there for the Azure Stack Hub Region, so you could run this script on the same system for multiple stamps.

2. Next, it uses the New-AzsCertificateSigningRequest function from the Readiness checker module to create the requests. it places them in the \requests directory.

3. After this, WinRM config is checked to see if the IP address of the CA server exists in Trusted Hosts. If not, it is added. All other entries are maintained.

4. A Session is established to the CA server, and the request files are copied to it.

5. On the CA server, Certutil.exe is used to retrieve the Public CA certificate and stored in a file.

6. On the CA server, CertReq.exe is used to submit each of the requests to the CA.

7. On the CA server, each request is approved using CertUtil -resubmit .

8. On the CA server, each Signed cert is retrieved and stored as a p7b and crt file.

9. Each signed cert is copied from the CA server to the local system where you’re running the script.

10. The Public CA certificate is copied from the CA server to the local system.

11. On the CA server, the working folder is deleted.

12. The remote PS Session is removed.

13. The Public CA certificate is imported in to the computers root store.

14. The directory structure required for validating certificates is created.

15. The signed certificates are imported.

16. The private certificates are exported and saved as a pfx file with password to the corresponding directory.

17. The certificates are validated using the Invoke-AzsCertificateValidation function from the Readiness checker module.

The folder structure for the certificates is as follows:

C:\AZSCERTS\AZS1
+---AAD
|   +---ACSBlob
|   |       blob.pfx
|   |
|   +---ACSQueue
|   |       queue.pfx
|   |
|   +---ACSTable
|   |       table.pfx
|   |
|   +---Admin Extension Host
|   |       adminhosting.pfx
|   |
|   +---Admin Portal
|   |       adminportal.pfx
|   |
|   +---ARM Admin
|   |       adminmanagement.pfx
|   |
|   +---ARM Public
|   |       management.pfx
|   |
|   +---KeyVault
|   |       vault.pfx
|   |
|   +---KeyVaultInternal
|   |       adminvault.pfx
|   |
|   +---Public Extension Host
|   |       hosting.pfx
|   |
|   \---Public Portal
|           portal.pfx
|
+---AppServices
|   +---API
|   |       api.pfx
|   |
|   +---DefaultDomain
|   |       wappsvc.pfx
|   |
|   +---Identity
|   |       sso.pfx
|   |
|   \---Publishing
|           ftp.pfx
|
+---DBAdapter
|       DBAdapter.pfx
|
+---EventHubs
|       eventhub.pfx
|
\---IoTHub
        mgmtiothub.pfx

I have written an example script new-AzsHubcertificatesexample.ps1 so that you can generate the correct parameter types, or create a new, unique Pfx password for use by the main script. Change the variables according to your environment. You could take this further by storing the pfx password in a KeyVault; maybe I’ll write a further post on how to do this … :)

ARM Limits on Azure Stack Hub

I came across an interesting error when I was doing some maintenance work on an Azure Stack Hub stamp. I was updating App Service to version 2020 Q2 and also installing the Event Hubs Public Release preview. I got the following error message:

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‘Number of read requests for subscription ‘‘ exceeded the limit of ‘15000’ for time interval ‘01:00:00’. Please try again after ‘‘ seconds. (Code: SubscriptionRequestsThrottled)’

I’d certainly not come across this before and was intrigued to see if I could find out any more information about this. I checked the Azure Stack Hub documentation and couldn’t find any reference to this limit, nor could I find anyone else who had come across this before.

What I did find related to Azure, so I thought it should be relevant. Details of the limits applied can be found in the article Throttling Resource Manager requests.

It turns out that Azure Stack Hub also applies limits to requests via ARM, although the limits are slightly different. Whereas for Azure the Read limit for a subscription is set to 12000, for Azure Stack Hub, it is set to 15000, per the error message I received.

I don’t know what the write / delete limits are, but assume they are similar to the ones set for Azure, give or take a thousand :)

So, how can you check how many read operations are remaining before hitting the limit?

The Throttling Resource Manager requests article details the methods you can use, by inspecting headers, or by using a script that was referenced in the doc:  Check Resource Manager Limits for a Subscription.

This script doesn’t quite work for Azure Stack Hub, also, it doesn’t work if you’re the the AZ PowerShell Module, so I made some modifications and made them available here.

There are two versions, one for AzureRM and the other for Az PowerShell modules

Get-AzArmLimits.ps1

Get-AzureRMArmLimits.ps1

You need to be logged in to the Azure environment you want to check, but it will work for Azure and Azure Stack Hub

Here are some examples of the output:

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Using AzureRM module; Azure

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Using AzureRM module; Azure Stack Hub

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Using Az module; Azure Stack Hub

Azure Stack Hub: When you can't view/add permissions in a tenant subscription from the portal

I have noticed on a few occasions that for a tenant subscription hosted in an Azure Stack region that I am either unable to view the IAM permissions, or add a user/service principal/group for the subscription. I have needed to do this to assign a service principal as a contributor to a subscription so that I can deploy a Kubernetes cluster via AKSE.

Typically for viewing the permissions, clicking on the Refresh button does the trick. More problematic is adding permissions via the portal. Doing so renders a screen like below:

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As highlighted, the animated ‘dots’ show the blade constantly trying to retrieve the data but can’t. It is actually a known issue and is highlighted in the release notes.

The remediation it offers is to use PowerShell to verify the permissions, and gives a link to the Get-AzureRmRoleAssignment CmdLet. Not helpful if you want to set permissions, so here’s a step-by-step description of what you’ll need to do.

Pre-Reqs:

• Your user account is the owner of the subscriptions when they were set up.

• You have the correct PowerShell for Azure Stack Hub installed

For the example shown, I am using Azure AD identities, I have more than one tenant subscription assigned to my user account and I am adding a service principal. At the end of the post, I will show the commands for adding a group or a user .

Step-By-Step

From PowerShell, connect to the tenant subscription you want to change the permissions on. The documentation is for connecting as an operator, so here’s how to do it as a user:

$Region = '<yourRegion>'
$FQDN = '<yourFQDN>'
$AADTenantName = '<yourAADTenantName>'
$envName = "AzureStack$region" 

 # Register an Azure Resource Manager environment that targets your Azure Stack instance. Get your Azure Resource Manager endpoint value from your service provider.
Add-AzureRMEnvironment -Name $envName -ArmEndpoint "https://management.$Region.$FQDN" `
    -AzureKeyVaultDnsSuffix vault.$Region.$FQDN `
    -AzureKeyVaultServiceEndpointResourceId https://vault.$Region.$FQDN

# Set your tenant name.
$AuthEndpoint = (Get-AzureRmEnvironment -Name $envName).ActiveDirectoryAuthority.TrimEnd('/')
$TenantId = (invoke-restmethod "$($AuthEndpoint)/$($AADTenantName)/.well-known/openid-configuration").issuer.TrimEnd('/').Split('/')[-1]

# After signing in to your environment, Azure Stack cmdlets
# can be easily targeted at your Azure Stack instance.
Add-AzureRmAccount -EnvironmentName $envName -TenantId $TenantId

As I have more than one subscription, let’s get a list so we can select the correct one:

Get-AzureRmSubscription | ft Name

I got the following output:

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• I want to modify the AKSTest subscription:

#Set the context
$ctx = set-azurermcontext -Subscription AKSTest
$ctx

Running that command, I get :

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Cool; I’ve got the correct subscription now, so let’s list the permissions assigned to it:

Get-AzureRmRoleAssignment

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OK, so those are the standard permissions assigned when the subscription is created. Let’s add a service principal.

First, let’s get the service principal object

Get-AzureRmADServicePrincipal | ? {$_.DisplayName -like '*something*'} |ft DisplayName

I want to assign AKSEngineDemo

$spn = Get-AzureRmADServicePrincipal -SearchString AKSEngineDemo

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Lets assign the service principal to the tenant subscription:

New-AzureRmRoleAssignment -ObjectId $spn.Id -RoleDefinitionName Contributor -scope "/subscriptions/$($ctx.Subscription.Id)"

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When I take a look in the portal now (after doing a refresh :) ), I see the following:

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Here’s the commands for adding an Azure AD User:

#Find the User object you want to add
Get-AzureRmADUser | ? {$_.DisplayName -like '*something*'} |ft DisplayName

#Assign the object using the displayname of the user
$ADUser = Get-AzureRmADUser -SearchString <UserName>
New-AzureRmRoleAssignment -ObjectId $ADUser.Id -RoleDefinitionName Contributor -scope "/subscriptions/$($ctx.Subscription.Id)"

Finally, how to add an Azure AD Group:

#Find the Group object you want to add
Get-AzureRmADGroup | ? {$_.DisplayName -like '*something*'} |ft DisplayName

#Assign the object using the displayname of the user
$ADGroup = Get-AzureRmADGroup -SearchString <GroupName>
New-AzureRmRoleAssignment -ObjectId $ADGroup.Id -RoleDefinitionName Contributor -scope "/subscriptions/$($ctx.Subscription.Id)"

Adding external load balancer IP address to an existing Kubernetes Service to update <pending>

This is one of those little things. I’m sure the veteran Kube admins out there are saying “well of course” but sometimes trying to sort through forums of Q&A on the internet is problematic even with the help of your favorite search engine. I thought I’d add one more page that might turn up and help someone else.

So you have created a self-managed K8s cluster and have you load balancer setup for your service and you have a bunch of <pending> when you look at your services. You can simply patch your service.

kubectl patch svc <svc-name> -n <namespace> -p '{"spec": {"type": "LoadBalancer", "externalIPs":["x.x.x.x"]}}