How to start vm from different subscription using Azure Automation Account - azure

Question

I have three subscription in same tenant say Sub1, Sub2 and Sub3. I have created Automation Account is in Sub1 and my VMs are in Sub3. (Cant create Automation account in Sub3 due to some restrictions). I want to write a powershell script which will start Sub3 VM.
When I ran Get-AzureRmSubscription it is giving me only my current subscription i.e. Sub1
My azure automation script is as below -
$connectionName = "AzureRunAsConnection"
try
{
# Get the connection "AzureRunAsConnection "
$servicePrincipalConnection=Get-AutomationConnection -Name $connectionName
"Logging in to Azure..."
Add-AzureRmAccount `
-ServicePrincipal `
-TenantId $servicePrincipalConnection.TenantId `
-ApplicationId $servicePrincipalConnection.ApplicationId `
-CertificateThumbprint $servicePrincipalConnection.CertificateThumbprint
}
catch {
if (!$servicePrincipalConnection)
{
$ErrorMessage = "Connection $connectionName not found."
throw $ErrorMessage
} else{
Write-Error -Message $_.Exception
throw $_.Exception
}
}
Get-AzureRmSubscription
# $context = Get-AzureRmSubscription -SubscriptionId {subId}
# Set-AzureRmContext $context
# Start-AzureRmVM -ResourceGroupName "ResourceName" -Name "VMName"
Can you please guide how can I go this?

Answer 1

Since your subscriptions are in the same tenant, you can directly assign an Azure RABC role to your Azure Automation connection(service principal ) in your Sub3. Then you can manage Azure resource in Sub3
For example
Get the Connection Application ID
Assign role
Connect-AzAccount
$sp=Get-AzADServicePrincipal -ApplicationId < the appId you copy>
Set-AzContext -SubscriptionId <the id of sub3>
#assign Contributor role to the connection at subsciprion level
New-AzRoleAssignment -ObjectId $sp.id -RoleDefinitionName Contributor
Test
$connectionName = "AzureRunAsConnection"
try
{
# Get the connection "AzureRunAsConnection "
$servicePrincipalConnection=Get-AutomationConnection -Name $connectionName
"Logging in to Azure..."
Add-AzureRmAccount `
-ServicePrincipal `
-TenantId $servicePrincipalConnection.TenantId `
-ApplicationId $servicePrincipalConnection.ApplicationId `
-CertificateThumbprint $servicePrincipalConnection.CertificateThumbprint
}
catch {
if (!$servicePrincipalConnection)
{
$ErrorMessage = "Connection $connectionName not found."
throw $ErrorMessage
} else{
Write-Error -Message $_.Exception
throw $_.Exception
}
}
Get-AzureRmSubscription