Get total number of Azure functions in a subscription

Question

I'm trying to find a query to list total number of Azure functions within a subscription using Azure Resource Graph Explorer.

I'm only able to get the total number of Function Apps and not the underlying functions.

Is there a way using Graph query? Or is there a script which I can use?

Note: Only interested in Azure Functions not the Azure Function App.

Answer 1

I do not think this is possible through a Resource Graph Query. One possible approach would be to use Azure REST API subsequently to get the results. Here is a PowerShell example:

You need to generate a Bearer token in order to query the REST API. You could use a function like this to generate it.

function Get-AzOauth2Token
{
    [CmdletBinding()]
    Param
    (
        [string]$TenantId,
        [string]$AppId,
        [string]$Secret
    )

    $result         =   Invoke-RestMethod -Uri $('https://login.microsoftonline.com/'+$TenantId+'/oauth2/token?api-version=1.0') -Method Post -Body @{"grant_type" = "client_credentials"; "resource" = "https://management.core.windows.net/"; "client_id" = "$AppId"; "client_secret" = "$Secret" }
    $authorization  =   ("{0} {1}" -f $result.token_type, $result.access_token)
    return $authorization
}

There are a lot of other ways to get a token though. However, I will use this to retrieve it...

$token = Get-AzOauth2Token -TenantId your_tenant -AppId your_spn_app_id -Secret your_secret

Then you would run your resource graph query in order to get all Function Apps across the tenant and in any subscription.

$query = Search-AzGraph "resources | where type =~ 'microsoft.web/sites' | where kind startswith 'functionapp'"
$results = Search-AzGraph -Query $query

...and finally execute the REST API Calls for all the Function Apps that the query returned.

$functions = @()

$results | ForEach-Object {

    $restMethod = 'GET'
    $restUri    = 'https://management.azure.com'+$_.ResourceId+'/functions?api-version=2022-03-01'
    $restHeader = @{
        'Authorization' = $token
        'Content-Type'  = 'application/json'
    }

    # Execute Call
    $request    = Invoke-RestMethod -Method $restMethod `
                                    -Uri $restUri `
                                    -Headers $restHeader

    $functions += $request

}

The $functions.value variable now holds all the different functions.

I suggest using the REST API instead of standard PowerShell cmdlets because it is faster in large environments - it prevents you from having to switch between subscriptions when you have resources spread across various subscriptions.

Answer 2

After reproducing from my end, I could able to achieve your requirement using the PowerShell script. Below is the script that worked for me.

$GetFunction=Get-AzFunctionApp -SubscriptionId <YOUR_SUBSCRIPTION_ID>
$ResourceGroup=($GetFunction).ResourceGroupName
$Name = ($GetFunction).Name
$Result=@()
For($I=0;$I -lt $ResourceGroup.count;$I++) {
        $obj = [PSCustomObject]@{
                ResourceGroup = $ResourceGroup[$I]
                FunctionAppName = $Name[$I]
                Function=(Get-AzResource -ApiVersion "2022-03-01" -Name $Name[$I] -ResourceGroupName $ResourceGroup[$I] -ResourceType "Microsoft.Web/sites/functions").ResourceName
            }
            $Result+=$obj
}
$Result

RESULTS:

Update

To get the count of number of functions in a function app, you can use .count.

$GetFunction=Get-AzFunctionApp -SubscriptionId <YOUR_SUBSCRIPTION_ID>
$ResourceGroup=($GetFunction).ResourceGroupName
$Name = ($GetFunction).Name
$Result=@()
For($I=0;$I -lt $ResourceGroup.count;$I++) {
    $Functions=(Get-AzResource -ApiVersion "2022-03-01" -Name $Name[$I] -ResourceGroupName $ResourceGroup[$I] -ResourceType "Microsoft.Web/sites/functions").ResourceName
        $obj = [PSCustomObject]@{
                ResourceGroup = $ResourceGroup[$I]
                FunctionAppName = $Name[$I]
                NoOfFunctions=$Functions.Count
                Functions=$Functions
    }
    $Result+=$obj
}
$Result

Update-2

$GetFunction=Get-AzFunctionApp -SubscriptionId <YOUR_SUBSCRIPTION_ID>
$ResourceGroup=($GetFunction).ResourceGroupName
$Name = ($GetFunction).Name
$Result=@()
$TotalFuncCount=0
For($I=0;$I -lt $ResourceGroup.count;$I++) {
    $Functions=(Get-AzResource -ApiVersion "2022-03-01" -Name $Name[$I] -ResourceGroupName $ResourceGroup[$I] -ResourceType "Microsoft.Web/sites/functions").ResourceName
        $obj = [PSCustomObject]@{
                ResourceGroup = $ResourceGroup[$I]
                FunctionAppName = $Name[$I]
                NoOfFunctions=$Functions.Count
                Functions=$Functions
    }
    $Result+=$obj
    $TotalFuncCount+=$Functions.Count
}
$Result
$TotalFuncCount