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
}