Adding an App Settings to existing Azure Web Application using Azure Power Shell

I want to write a script that run using azure power shell to automate adding the Web Application configuration

Azure > MyWebApp > Application Settings > App settings

It's look like key = "value"

I write this script

###########################
# MyApp Config Automation #
###########################

#Begin

$subscriptionName="MySubscriptionName"
$webSiteName="MyWebAppName"
$storageAccountName="StorageAccountName"
########################################
$userName = "[email protected]"
$securePassword = ConvertTo-SecureString -String "mypass" -AsPlainText -Force
#####################################
$cred = New-Object System.Management.Automation.PSCredential($userName, $securePassword)
#####################################
Add-AzureAccount -Credential $cred 
Select-AzureSubscription -SubscriptionName $subscriptionName -Default
#####################################
Get-AzureWebsite -Name $webSiteName

#End

but i know that the above script is only get my web application, now i need to access MyWebApp > Application Settings > App settings and give the script file/array of my new App settings and the script check if there are any new App Settings key it will add it to App Settings, if there are any existing keys it will override it's value. What is the steps or APIS or can i do that with azure power shell?

Edit: This script can Automate creating new web application and adding App Settings to it:

##############################################
# Creating website and Adding Configs Script #
##############################################

$webSiteName="mywebsite"
$storageAccountName="storageaccount"
$subscriptionName="mysubsc"
$userName = "myaccount"
$securePassword = ConvertTo-SecureString -String "mypass" -AsPlainText -Force
$cred = New-Object System.Management.Automation.PSCredential($userName, $securePassword)
Add-AzureAccount -Credential $cred 
Select-AzureSubscription -SubscriptionName $subscriptionName -Default

New-AzureWebsite -Name $webSiteName
New-AzureStorageAccount –StorageAccountName $storageAccountName -Location "South Central US"
$ClientId="dfgdf6"
$Password="ffefe"
$StorageAccountKey = Get-AzureStorageKey -StorageAccountName $storageAccountName
$AppSettings = @{"StorageAccountPrimary" = $StorageAccountKey.Primary;"StorageAccountSecondary" = $StorageAccountKey.Secondary;"ida:ClientId"=$ClientId;"ida:Password"=$Password}

Set-AzureWebsite -Name $webSiteName -AppSettings $AppSettings

Here's an update to it based on the 12/2015 Azure PowerShell commands. The example is for slot-specific settings, if you want global, use Get/Set-AzureRmWebApp and remove the -slot parameter.

$myResourceGroup = 'PartsUnlimitedMRP'
$mySite = 'centpartsunlimited'

$webApp = Get-AzureRMWebAppSlot -ResourceGroupName $myResourceGroup -Name $mySite -Slot production
$appSettingList = $webApp.SiteConfig.AppSettings

$hash = @{}
ForEach ($kvp in $appSettingList) {
    $hash[$kvp.Name] = $kvp.Value
}

$hash['NewKey'] = "NewValue"
$hash['ExistingKey'] = "NewValue"

Set-AzureRMWebAppSlot -ResourceGroupName $myResourceGroup -Name $mySite -AppSettings $hash -Slot production

Retrieve App Settings

First set these two variables.

$myResourceGroup = 'RESOURCE_GROUP_NAME'
$mySite = 'SITE_NAME'

Then switch to the new Resource Manager mode and sign-in to your account.

Switch-AzureMode AzureResourceManager
Get-AzureAccount

Then retrieve the app settings. (Note that a back tick (`) means a new line.)

(Invoke-AzureResourceAction -ResourceGroupName $myResourceGroup `
 -ResourceType Microsoft.Web/sites/Config -Name $mySite/appsettings `
 -Action list -ApiVersion 2015-08-01 -Force).Properties

Add/Update App Settings

To update settings, first put them into a variable.

$props = (Invoke-AzureResourceAction -ResourceGroupName $myResourceGroup `
 -ResourceType Microsoft.Web/sites/Config -Name $mySite/appsettings `
 -Action list -ApiVersion 2015-08-01 -Force).Properties

To use Set-AzureWebsite convert the variable to a hash table.

 $hash = @{}
 $props | Get-Member -MemberType NoteProperty | % { $hash[$_.Name] = $props.($_.Name) }

Now add/update values in the hash table.

$hash.NewKey = "NewValue"
$hash.ExistingKey = "NewValue"

Then switch back to Service Management mode and commit the settings.

Switch-AzureMode AzureServiceManagement
Set-AzureWebsite -Name $mySite -AppSettings $hash

Complete Code Listing

$myResourceGroup = 'RESOURCE_GROUP_NAME'
$mySite = 'SITE_NAME'

Switch-AzureMode AzureResourceManager
Get-AzureAccount

(Invoke-AzureResourceAction -ResourceGroupName $myResourceGroup `
 -ResourceType Microsoft.Web/sites/Config -Name $mySite/appsettings `
 -Action list -ApiVersion 2015-08-01 -Force).Properties

$props = (Invoke-AzureResourceAction -ResourceGroupName $myResourceGroup `
 -ResourceType Microsoft.Web/sites/Config -Name $mySite/appsettings `
 -Action list -ApiVersion 2015-08-01 -Force).Properties

 $hash = @{}
 $props | Get-Member -MemberType NoteProperty | % { $hash[$_.Name] = $props.($_.Name) }

$hash.NewKey = "NewValue"
$hash.ExistingKey = "NewValue"

Switch-AzureMode AzureServiceManagement
Set-AzureWebsite -Name $mySite -AppSettings $hash

Notes

The AzureServiceManagement and AzureResourceManager are not meant for use in the same session. For now the latter does not seem to permit updating the app settings via Set-AzureResource. The above is a workaround. Another way is to use the Azure CLI instead of PowerShell.