Just for those poor souls googling this error:

get-azurermvm : Your Azure credentials have not been set up or have expired, please run Connect-AzureRmAccount to set
up your Azure credentials.

Or any other command after Connect-AzureRMAccount with the -tenantId switch specified.

Took me over an hour to figure out that the tenant ID is actually case sensitive as the error is confusing, the log in works fine but subsequent commands fail.

Azure has a very nice feature called ‘Dynamic Groups‘. We use these in our customer tenants to dynamically generate a group with actual users, excluding Guest accounts (marked with #EXT#).

As I couldn’t find any articles detailing how to create a Dynamic Group through the Graph API, I’m posting this for whoever it helps 🙂

$dynamicGroupProperties = @{
    "description" = "Dynamic Group Created through the Graph API";
    "displayName" = "Dynamic Group Created through the Graph API";
    "groupTypes" = @("DynamicMembership");
    "mailEnabled" = $False;
    "mailNickname" = "testnickname";
    "membershipRule" = "(user.userPrincipalName -notContains `"#EXT#@`") -and (user.userType -ne `"Guest`")";
    "membershipRuleProcessingState" = "On";
    "securityEnabled" = $True
}

invoke-webrequest -Headers $headerParams -uri "https://graph.microsoft.com/beta/groups" -Body (ConvertTo-Json $dynamicGroupProperties) -method POST -Verbose

If you’re not yet used to working with the Graph API, read up on how to connect to the Graph API using Powershell.

A handy Powershell function to lock / unlock using .NET, to prevent concurrent read/writes to files or anything else you like.

function handleThreadLock{
    Param(
        [switch]$setLock,
        [switch]$releaseLock,
        [string]$lockName="defaultLockName",
        [int]$timeOut=600
    )
    if($setLock){
        #register a thread lock
        $script:threadLock = New-Object System.Threading.Mutex($false, $lockName)
        $waited = 0
        while($true){
            try{$lockState = $script:threadLock.WaitOne(1000)}catch{$lockState=$False}
            if($lockState){
                break
            }else{
                $waited+=1
                if($waited -gt $timeOut){
                    Throw "failed to get a thread within $timeOut seconds!"
                }
            }
        }
    }  
    if($releaseLock){
        #release a thread lock
        [void]$script:threadLock.ReleaseMutex()
    }  
}

In your script, call it like this:

try{
    handleThreadLock -setLock
}catch{Throw "Failed to set lock!"}

try{
    add-content -Path "c:\yourfile.txt" -Value "log entry" -ErrorAction Stop
}finally{
    handleThreadLock -releaseLock
}