swarm-nat/expose_forwards.ps1

#Requires -Modules powershell-yaml
$ErrorActionPreference = 'Stop'

foreach($yaml in (Get-ChildItem -Filter '*.yml')) {
    Write-Output ('Processing {0}' -f $yaml)
    $definition = Get-Content -Path $yaml -Raw | ConvertFrom-Yaml

    foreach($port in $definition.services.Values.ports) {
        $nat = @{
            protocol = $null
            public_ip = $null
            public_port = $null
            internal_port = $null
        }

        if($port.Count -eq 4) {
            #long form
            $published_splitted = $port.published -split ':'

            $nat.protocol = $port.protocol
            $nat.public_ip = $published_splitted[0]
            $nat.public_port = $port.target
            $nat.internal_port = $published_splitted[1]
        } else {
            #short form
            $ports_splitted = $port -split ':'

            $nat.public_ip = $ports_splitted[0]
            $nat.public_port = $ports_splitted[2]
            $nat.internal_port = $ports_splitted[1]
        }

        if(!$nat.protocol) {
            #this is also Docker's default
            $nat.protocol = 'tcp'
        }
        if($nat.Values -contains $null) {
            #if $nat doesn't conatain all needed attributes skip the port
            $error_message = 'Skipping port, because $nat contains $null: {0}' `
                             -f ($nat | ConvertTo-Json)
            Write-Error -Message $error_message `
                        -ErrorAction Continue
            continue
        }

        if($nat.internal_port -ne $nat.public_port) {
            Write-Output ('Additional NAT rule required, because published {0} and target {1} differ' `
                          -f $nat.internal_port,$nat.public_port)
            $nat.protocol
            $nat.public_ip
            $nat.public_port
            $nat.internal_port
        }
    }
}