Authenticate multiple Azure Powershell Functions - powershell

Question

I have built a few Powershell functions using Azure Functions, and it is working like a charm.
Now that I have proven the concept I would very much like to refactor my existing functions.
First of all I would like to move the authentication required in my function to some kind of shared function or whatever.
Here is my example function, which return a list of all web apps in my resource group.
# Authenticate with subscription
$subscriptionId = "<SubscriptionId>"
$resourceGroupName = "<ResourceGroupName>";
$tenantId = "<TenantId>"
$applicationId = "<ApplicationId>"
$password = "<Password>"
$userPassword = ConvertTo-SecureString -String $password -AsPlainText -Force
$userCredential = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList $applicationId, $userPassword
Add-AzureRmAccount -TenantId $tenantid -ServicePrincipal -SubscriptionId $subscriptionId -Credential $userCredential
Get-AzureRmSubscription –SubscriptionId $subscriptionId | Select-AzureRmSubscription
# Get all web apps
$Websites = Get-AzureRmWebApp -ResourceGroupName $resourceGroupName
$Websites = $Websites | select name | ConvertTo-Json -Compress
# Write output
Out-File -Encoding Ascii -FilePath $res -inputObject $Websites
I would very much like to move everything from line 1 to line 10 somewhere else. Is it possible? If yes, can anyone please point me in the right direction here?
Update
Thanks to both Walter and Pragna I combined the two methods like this.
run.ps1
# Authenticate with subscription
Import-Module 'D:\home\site\wwwroot\bin\Authentication.ps1'
# Get all web apps
$Websites = Get-AzureRmWebApp -ResourceGroupName $env:ResourceGroupName
$Websites = $Websites | select name | ConvertTo-Json -Compress
# Write output
Out-File -Encoding Ascii -FilePath $res -inputObject $Websites
Authentication.ps1
$secpasswd = ConvertTo-SecureString $env:Password -AsPlainText -Force;
$userCredential = New-Object System.Management.Automation.PSCredential ($env:ApplicationId, $secpasswd)
Add-AzureRmAccount -TenantId $env:TenantId -ServicePrincipal -SubscriptionId $env:SubscriptionId -Credential $userCredential
Get-AzureRmSubscription –SubscriptionId $env:SubscriptionId | Select-AzureRmSubscription

Answer 1

It is unsafe for you to save your account information in script. I suggest you could store these to App Setting. You could find it Your function app-->Settings-->Application settings-->Manage application settings-->App settings and key-value pairs for the settings SP_USERNAME, SP_PASSWORD, and TENANTID, SubscriptionId(You also could use other values or more key pairs).
Modify your script as below:
# Set Service Principal credentials
# SP_PASSWORD, SP_USERNAME, TENANTID are app settings
$secpasswd = ConvertTo-SecureString $env:SP_PASSWORD -AsPlainText -Force;
$mycreds = New-Object System.Management.Automation.PSCredential ($env:SP_USERNAME, $secpasswd)
Add-AzureRmAccount -ServicePrincipal -Tenant $env:TENANTID -Credential $mycreds;
Get-AzureRmSubscription –SubscriptionId $env:subscriptionId | Select-AzureRmSubscription
When you want to modify your account information, you don't need modify your script, you only need modify app setting. You could modify app setting by using Azure CLI.

Answer 2

Yes. You can import custom powershell modules.
Create a shared directory e.g. bin under D:\home\site\wwwroot
Copy module to the shared directory
Call Import-Module SharedDir\MyModule.psm1 or SharedDir\MyScript.ps1 or SharedDir\MyModule.psd1 or SharedDir\MyLib.dll
Also, here is a sample that might help.