Provision-Office365GroupsForTesting.ps1

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function Get-Token {
  [CmdletBinding()]
  param
  (
    [Parameter(Mandatory = $true)][string]$Tenant,
    [Parameter(Mandatory = $true)][System.Guid]$ClientID,
    [Parameter(Mandatory = $true)][string]$ClientSecret,
    [Parameter(Mandatory = $true)][string]$Resource
  )
  
  begin {
  }

  process {
    $ReqBody = @{
      Grant_Type    = "client_credentials"
      Scope         = "$Resource.default"
      client_Id     = $ClientID
      Client_Secret = $ClientSecret
    } 
    
    $RequestToken = @{
      ContentType = 'application/x-www-form-urlencoded'
      Method      = 'POST'
      Body        = $ReqBody
      Uri         = "https://login.microsoftonline.com/$Tenant/oauth2/v2.0/token"
    }

    try {
      $response = Invoke-RestMethod @RequestToken
    }
    catch {
      Write-Error $_.Exception
    }
  }
  end {
    $response
  }
}

function Get-AuthenticationHeaders {
  [CmdletBinding()]
  param
  (
    [Parameter(Mandatory = $true)][string]$AccessToken
  )

  begin {
  }
  process {
    @{
      'Content-Type'  = 'application/json'
      'Authorization' = "Bearer $($AccessToken)"
    }    
  }
  end {
  }
}

function Split-ArrayIntoChunks {
  [CmdletBinding()]
  param
  (
    [Parameter(Mandatory = $true)][object[]]$Array,
    [Parameter(Mandatory = $true)][int]$ChunkSize
  )

  begin {
    $counter = [pscustomobject] @{ Value = 0 }
  }
  process {
    $Array | Group-Object -Property { [math]::Floor($counter.Value++ / $ChunkSize) }
  }
  end {
  }
}

function CreateBatch-NewO365Group {
  [CmdletBinding()]
  param
  (
    [Parameter(Mandatory = $true)]$Groups
  )

  begin {
  }
  process {
    @{
      "requests" = @(foreach ($group in $Groups) { 
          @{
            "id"      = $group.mailNickname
            "url"     = "/groups"
            "method"  = "POST"
            "headers" = @{
              "Content-Type" = "application/json"
            }
            "body"    = $group
          }
        })
    } | ConvertTo-Json -Depth 5 -Compress
  }
  end {
  }
}


function Process-GraphBatch {
  [CmdletBinding()]
  param
  (
    [Parameter(Mandatory = $true)][string]$Payload,
    [Parameter(Mandatory = $true)][string]$AccessToken
  )

  begin {
    $headers = Get-AuthenticationHeaders -AccessToken $AccessToken
    $uri = "https://graph.microsoft.com/v1.0/`$batch"
  }
  process {
    try {
      $response = Invoke-RestMethod -Uri $uri -Headers $headers -Body $Payload -Method Post

      foreach ($batchResponse in $response.responses) {
        if ($batchResponse.status -ge 400) {
          Write-Error "Error in batch request: $($batchResponse.id). Error: $(ConvertTo-Json $batchResponse.body.error -Depth 5)"
        }
      }             
    }
    catch {
      Write-Error "Error sending batch request. Error: $($_.Exception)"
    }
  }
  end {
    $response
  }
}


# script requries Group.ReadWrite.All and Directory.ReadWrite.All
$tenant = "contoso.onmicrosoft.com"
$clientId = "xxxxxxx-xxxx-xxxx-xxxx-xxxxxxx"                # aka "Application ID" in Azure Portal > Azure Active Directory > App Registrations
$clientSecret = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"     # aka "Keys" in Azure Portal > Azure Active Directory > App Registrations

# Graph $batch limit is 20
# https://developer.microsoft.com/en-us/graph/docs/concepts/known_issues#json-batching
$batchSize = 20

$groupStartIndex = 1
$groupEndIndex = 500
$groupPrefix = "zDemoGroup"
$groupDefaultOwner = "admin@$tenant"
$groupDefaultMember = "alexw@$tenant"

if ( -not $token -or $token.ExpiresOn.DateTime -lt (Get-Date) ) {
  $token = Get-Token -Tenant $tenant -ClientID $clientId -ClientSecret $clientSecret -Resource "https://graph.microsoft.com/"
}

if ( $token.access_token ) {
  $groups = @()
  $groupStartIndex..$groupEndIndex | ForEach-Object {
    $groupName = "$($groupPrefix)$_"
    $groups += @{
      "mailNickname"       = "$groupName" 
      "displayName"        = "$groupName"
      "description"        = "$groupName - Created by Graph API"
      "mailEnabled"        = $true
      "securityEnabled"    = $true
      "groupTypes"         = @("Unified")
      "owners@odata.bind"  = @(
        "https://graph.microsoft.com/v1.0/users/$groupDefaultOwner"
      )
      "members@odata.bind" = @(
        "https://graph.microsoft.com/v1.0/users/$groupDefaultMember"
      )
    }
  }

  Write-Host "Splitting $($groups.Count) groups into $([Math]::Ceiling($groups.Count / $batchSize)) batches..."
  $batches = Split-ArrayIntoChunks -Array $groups -ChunkSize $batchSize

  # Iterate each batch of users to create Graph $batch JSON payload
  for ($idx = 0; $idx -lt $batches.Length; $idx++) {
    $batch = $batches[$idx].Group

    Write-Host "Processing Batch: $($idx + 1) of $($batches.Length) [Batch Size: $($batch.Count)]"

    $batchPayload = CreateBatch-NewO365Group -Groups $batch

    Process-GraphBatch -Payload $batchPayload -AccessToken $token.access_token | Out-Null
  }
}