related to http://blogs.bitesinbyte.com/

database-backup.ps1

param(
    [string]$storageAccount,
    [string]$blobContainer,
    [string]$instanceName,
    [string]$databaseName,
    [string]$storageKey
)
import-module sqlps;

$sqlPath = "sqlserver:\sql\$($env:COMPUTERNAME)"
$credentialName = "backupCredential-$(Get-Random)"
$backupFile = "AxDB_PAR_$(Get-Date -Format yyyy_MM_dd_HH_mm_ss).bak"
$path = "$($sqlPath)\$($instanceName)\credentials"
$backupUrlContainer = "https://$storageAccount.blob.core.windows.net/$blobContainer/$($backupFile)"
$removePath = "$($path)\$($credentialName)"
$secureString = ConvertTo-SecureString $storageKey -AsPlainText -Force


try {
    Set-Location $sqlPath

    $secureString = ConvertTo-SecureString $storageKey -AsPlainText -Force
    
    Write-Host "Generate credential: " $credentialName
    New-SqlCredential -Name $credentialName -Identity $storageAccount -Secret $secureString -Path $path -ea Stop | Out-Null
    
    Write-Host "Backup database: " $backupUrlContainer
    
    Backup-SqlDatabase -Database $databaseName -Path $path -SqlCredential $credentialName -BackupFile $backupUrlContainer -BackupAction Database -NoRewind -BackupSetName "AxDB-Full Database Backup" -CompressionOption On
    
    Write-Host "Remove credential: " $credentialName
    Remove-SqlCredential -Path $removePath -ea Stop | Out-Null
    }catch{ Write-Host $_.Exception.Message }
    
    Write-Host "Done"

pipeline-backup.yaml

trigger: none
pool:
  vmImage: ubuntu-latest

variables:
  - group: Database-Backup

steps:
- task: AzureCLI@2
  displayName: Start the VM
  inputs:
    azureSubscription: $(AZVMServiceConnection)
    scriptType: pscore
    scriptLocation: inlineScript
    inlineScript: az vm start -g $(VMResourceGroup) -n $(VMName)

- task: AzureCLI@2
  name: storageKeyTask
  displayName: Fetch Storage Account Key
  inputs:
    azureSubscription: $(AZBackupServiceConnection)
    scriptType: pscore
    scriptLocation: inlineScript
    inlineScript: |
      $storageKey = az storage account keys list -g $(StorageAccountResourceGroup) -n $(StorageAccount) --query [0].value
      echo "##vso[task.setvariable variable=storageSecretKey;issecret=true]$storageKey"
      
- task: AzureCLI@2
  displayName: Run VM Command
  inputs:
    azureSubscription: $(AZVMServiceConnection)
    scriptType: pscore
    scriptLocation: inlineScript
    inlineScript: az vm run-command invoke --command-id RunPowerShellScript -g $(VMResourceGroup) -n $(VMName) --scripts '@database-backup.ps1' --parameters 'storageAccount=$(StorageAccount)' 'blobContainer=$(BlobContainer)' 'instanceName=$(InstanceName)' 'databaseName=$(DatabaseName)' 'storageKey=$(storageSecretKey)'

- task: AzureCLI@2
  displayName: Stop the VM
  continueOnError: true
  inputs:
    azureSubscription: $(AZVMServiceConnection)
    scriptType: pscore
    scriptLocation: inlineScript
    inlineScript: az vm deallocate -g $(VMResourceGroup) -n $(VMName)