dvm.ps1

# Spawns docker containers as lightweight VMs
# very convenient optionless

function dvm {
  param (
        [Parameter(ValueFromRemainingArguments=$true)]
        [string[]]$args
  )
  
  $ErrorActionPreference = "Stop"
  
  $selfLabel = "dvm"

  if (-not (Test-Path \\.\pipe\docker_engine)) {
    & docker desktop start
  }
  
  if (-not $args) {
    docker container ls --filter "label=$selfLabel" --all --format "table {{ .Image }}\t{{ .Names }}\t{{ .State }}\t{{ .RunningFor }}"
    return
  }
  
  $arg0 = $args[0]
  
  if ($arg0[0] -eq "-") {
    $toRemove = (docker container ls --filter "label=$selfLabel" --all --format "{{ .Names }}") | Where-Object { $_ -like $arg0.Substring(1) }
    if ($toRemove) {
      docker container rm --force $toRemove
    }
    return
  }

  $containers = & docker container ls --filter "label=$selfLabel" --all --format "{{ .Names }}\t{{ .State }}\t{{ .Image }}"

  $shorthand = $arg0.Substring(0, 2).ToLower()
  $dupids = @()

  foreach ($line in $containers) {
    $name, $state, $image = $line -split "`t"

    if ($name -eq $arg0) {
      $ident = "${name} + $image"

      if ($state -ne "running") {
        Write-Host -ForegroundColor Magenta "> $ident - starting"
        $null = docker container start $name
      } else {
        Write-Host -ForegroundColor Magenta "> $ident"
      }
      
      docker container exec --interactive --tty $name bash --login
      
      $ps = docker container exec $name find /proc -regex '/proc/[0-9]+'
      
      if ($ps[0] -eq "/proc/1" -and $ps.Length -le 2) {
        $null = docker container kill $name
        Write-Host -ForegroundColor Magenta "< $ident - stopped"
      } else {
        Write-Host -ForegroundColor Magenta "< $ident - $($ps.Length - 2) processes remaining"
      }
      
      return
    }

    if ($name -match "^$shorthand(\d+)$") {
      $dupids += [int]$Matches[1]
    }
  }
  
  if ($arg0 -match "^\w\w\d+") {
    throw "No container name matching $arg0"
    return
  }

  $id = 0
  while ($dupids -contains $id) {
    $id++
  }

  $name = $shorthand + $id
  $hostname = $name + "--" + $arg0 -replace "\W", "-"

  $null = docker container create `
    --label $selfLabel `
    --interactive --tty --network host `
    --hostname $hostname --name $name `
    $arg0 `
    sleep infinity

  Write-Host -ForegroundColor Magenta $Name
}