steps-get-or-create-vnet.yaml

parameters:
  prefix:                    ''
  suffix:                    ''

steps:
- task: AzureCLI@2
  displayName: 'Select VNets for stamps'
  inputs:
    azureSubscription: '$(azureServiceConnection)'
    scriptType: pscore
    scriptLocation: inlineScript
    inlineScript: |

      $prefix = "${{ parameters.prefix }}"
      $suffix = "${{ parameters.suffix }}"

      # Hashtable of VNet IDs per stamp location
      $vnets = @{}
      $stampLocations = '$(stampLocations)' | ConvertFrom-Json -NoEnumerate

      $vnetFile = "$(System.DefaultWorkingDirectory)/.ado/pipelines/config/vnets-$(environment).json"

      # Check if any pre-provisioned VNets have been specified for this enviroment by checking the existence of the file
      if(Test-Path $vnetFile)
      {
        echo "*** Using pre-provided VNets from file $vnetFile"

        # Load available pre-provided VNets
        $availableVnets = Get-Content $vnetFile | ConvertFrom-JSON

        foreach($location in $stampLocations)
        {
          # Pick list of regional VNets
          $vnetsInLocation = $availableVnets.$location
          if(-not $vnetsInLocation)
          {
            throw "*** ERROR: List of VNets in $vnetFile does not contain desired stamp region $location"
          }

          $earmarkTagName = "AlwaysOnVnetUsedBy"
          $earmarkTagValue = "$prefix$suffix-$location"

          echo "*** Attempting to find a VNet for deployment $earmarkTagValue"

          # check if any VNet was already earmarked earlier. Then we can skip the other search
          $vnet = az network vnet list --query "[?tags.$earmarkTagName == '$earmarkTagValue']" | ConvertFrom-Json
          if($vnet)
          {
            echo "*** VNet $($vnet.name) was already used before be this same deployment ($earmarkTagValue). Will use this VNet again"
            $vnets[$location] = $vnet.id
          }
          else
          {
            foreach($vnetId in $vnetsInLocation)
            {
              echo "*** Checking if VNet is in use: $vnetId"
              $vnet = az network vnet show --ids $vnetId | ConvertFrom-Json
              if(-not $vnet)
              {
                throw "*** ERROR $vnetId not found"
              }

              if(-not $vnet.tags.$earmarkTagName)
              {
                # Use this VNet as it was not earmarked yet by any other release
                echo "*** VNet $($vnet.name) not earmarked. Will use this VNet"

                $vnets[$location] = $vnetId

                $tagKeyVaule = "$earmarkTagName=$earmarkTagValue"

                echo "*** Adding earmark tag to VNet: $tagKeyVaule"

                # Add a tag to mark this VNet being used by this deployment
                az tag update --operation merge --resource-id $vnetId --tags $tagKeyVaule

                break
              }
              else
              {
                echo "*** VNet $($vnet.name) not available as it is earmarked by release $($vnet.tags.$earmarkTagName)"
              }
            }
          }

          if(-not $vnets[$location])
          {
            throw "*** ERROR no available VNet found for location $location"
          }

          # Check DNS settings on each VNet. They need to be set to Default (Azure-provided)
          foreach($vnetId in $vnets.Values)
          {
            $dns = az network vnet show --ids $vnetId --query "dhcpOptions.dnsServers" | convertfrom-json # If DNS is set to Default, this call will come back empty
            if($dns)
            {
              throw "*** VNet $vnetId has custom DNS servers set ($dns)! DNS settings must use 'Default (Azure-provided)' in order to work correctly with Private Endpoints. If you need custom DNS resolution, you need to set up Azure DNS Private resolver (https://learn.microsoft.com/azure/dns/dns-private-resolver-overview)"
            }
          }
        }
      }
      else
      {
        echo "*** No pre-provided VNets defined (file not found: $vnetFile). Creating temporary VNets..."
        # This is usually the case for E2E: we do not have pre-provided VNets here, so we need to create them first

        $rgName = "$prefix$suffix-networks-rg"

        # Since the VNets are not connected, we can use the same address space for all.
        # This value can be adjusted as needed
        $addressSpace = "10.1.0.0/18"

        foreach($location in $stampLocations)
        {

          $vnetName = "$prefix$suffix-$location-vnet"

          # check if the VNet already exists (from a previous run of this job)
          $vnet = az network vnet list --query "[?name=='$vnetName']" | ConvertFrom-JSON

          if($LastExitCode -ne 0)
          {
              throw "*** Error on checking existing VNet $vnetName"
          }

          if($vnet)
          {
            echo "*** VNEt $vnetName already exists"
            $vnets[$location] = $vnet.id
          }
          else
          {
            # We use a dedicated resource group for all the VNets for this deployment
            echo "*** Check if Resource Group $rgName exists"
            $checkRg = az group exists --name $rgName | ConvertFrom-Json
            if (!$checkRg) {
              Write-Warning "*** Resource Group $rgName does not exist. Creating..."
              # get the stamp locations and use the first one to create the resource group there.
              az group create --name $rgName --location $location

              if ($LastExitCode -eq 1) {
                Write-Error "*** Error - could not create resource group"
              }
            }

            echo "*** Creating new VNet $vnetName for E2E environment..."
            $vnet = $(az network vnet create -n $vnetName -g $rgName -l $location --address-prefixes $addressSpace) | ConvertFrom-JSON
            $vnets[$location] = $vnet.newVnet.id
          }
        }
      }

      $vnetsJson = $vnets | ConvertTo-Json -Compress

      echo "*** List of VNets per location: $vnetsJson"

      # Write map of VNet Resource IDs per stamp location which when then be used for Terraform input
      echo "##vso[task.setvariable variable=tfParameterVnetResourceIds]$vnetsJson"