Updates the HostName property of SSH hosts that are Hyper-V virtual machines to the (dynamic) IPv4 addresses of their network interfaces

fix-ssh-config-for-hyper-v-hosts.ps1

$ErrorActionPreference = "Inquire"

$SshConfigPath = "C:\Users\Tobias\.ssh\config"

$lines = Get-Content -Path $SshConfigPath
for ($i = 0; $i -le $lines.Count; $i++) {
  if ($lines[$i] -notmatch '^# auto-fix: (?<VirtualMachineName>[^ ]+) (?<NetworkAdapterName>[^ ]+)$') {
    continue
  }
  $VirtualMachineName = $Matches.VirtualMachineName
  $NetworkAdapterName = $Matches.NetworkAdapterName

  if ($lines[++$i] -notmatch '^Host (?<SshHost>.*)$') {
    $offending_line = $lines[$i]
    throw "Expected a 'Host' line after '# auto-fix', but found '$offending_line'"
  }
  $SshHost = $Matches.SshHost

  if ($lines[++$i] -notmatch '^  HostName (?<OldHostName>.*)$') {
    $offending_line = $lines[$i]
    throw "Expected a 'HostName' line after '# auto-fix' and 'Host', but found '$offending_line'"
  }
  $OldHostName = $Matches.OldHostName

  Write-Host "Fixing SSH config for host '$SshHost'."
  Write-Host "The current host name is '$OldHostName'."
  Write-Host "Determining IPv4 address of VM '$VirtualMachineName' using '$NetworkAdapterName'."
  $ip = Get-VM -Name $VirtualMachineName | Select -ExpandProperty NetworkAdapters | Where-Object -Property Name -Value $NetworkAdapterName -eq | Select-Object -Property IPAddresses | foreach { $_.IPAddresses | Where { $_ -Match "\d+\.\d+\.\d+\.\d+" } }
  if (!$ip) {
    throw "No IPv4 address was found for virtual machine '$VirtualMachineName' and network adapter '$NetworkAdapterName'."
  }

  Write-Host "The new host name is '$ip'."
  $lines[$i] = "  HostName $ip"
}

Write-Host "Updating $SshConfigPath"
Set-Content -Path $SshConfigPath -Value $lines