Add print server for label printer to have it easily usable via SSH

Add and configure a print server for the Brother P-touch QL 500 label
printer, so that it can be easily used via SSH.

Do the following to make that work:
- Configure the print server host.
- Package printer-driver-ptouch to have a working driver for the label
  printer.
- Configure CUPS.
- Add a script "forcecommand-lpr-wrapper", which works together with the
  ForceCommand sshd_config option and wraps lpr to provide an easy
  interface to use the Brother QL 500 label printer via SSH.
- Add a print user and configure SSH to have the
  "forcecommand-lpr-wrapper" script accessible without a password using
  the print user via SSH.
This commit is contained in:
June 2024-04-14 18:46:51 +02:00
parent 6a0218c132
commit c97f169b77
Signed by: june
SSH key fingerprint: SHA256:o9EAq4Y9N9K0pBQeBTqhSDrND5E7oB+60ZNx0U1yPe0
7 changed files with 248 additions and 0 deletions

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{ ... }:
{
networking.hostName = "ptouch-print-server";
system.stateVersion = "23.11";
}

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{ ... }:
{
imports = [
./configuration.nix
./networking.nix
./printing.nix
];
}

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#!/usr/bin/env python3
# A script for usage with the ForceCommand sshd_config option.
# It calls lpr with some standard arguments, but also parses
# SSH_ORIGINAL_COMMAND to potentially provide a different set of arguments to
# lpr.
#
# This wrapper is written for interacting with the Brother QL 500 label printer.
#
# The following options can be provided as an SSH command and this script will
# then pass them to the lpr call: <MediaType> <PageSize>
# - MediaType can be one of:
# - Labels
# - Tape (this is the default)
# - PageSize can be one of:
# - 12mm
# - 12mm-circular
# - 17x54mm
# - 17x87mm
# - 23x23mm
# - 24mm-circular
# - 29mm
# - 29x90mm
# - 38mm
# - 38x90mm
# - 50mm
# - 54mm
# - 58mm-circular
# - 62mm
# - 62x29mm
# - 62x100mm
# - Custom.WIDTHxHEIGHT (with WIDTH and HEIGHT needing to be either one to
# three digits)
# - label-wide (this being a convenience alias for Custom.62x35mm and it also
# being the default)
# - label-item (this being a convenience alias for 38x90mm)
#
# So using these options in a complete setup would look like this for example:
# cat label-item.pdf | ssh print@ptouch-print-server.z9.ccchh.net labels label-item
# This being equivalent to:
# cat label-item.pdf | ssh print@ptouch-print-server.z9.ccchh.net Labels 38x90mm
#
# The options are case-insensitive.
#
# The options are derived from: lpoptions -p Brother-QL-500 -l
import os, re, subprocess
mediaType = "Tape"
pageSize = "Custom.62x35mm"
def parseGivenOptions():
givenOptionsString = os.environ["SSH_ORIGINAL_COMMAND"]
givenOptionsIterator = iter(givenOptionsString.split(" "))
givenMediaType = next(givenOptionsIterator, "")
givenPageSize = next(givenOptionsIterator, "")
global mediaType
if givenMediaType.lower() == "labels":
mediaType = "Labels"
elif givenMediaType.lower() == "tape":
mediaType = "Tape"
global pageSize
pageSizeRegex = re.compile(r"^((12mm(-circular)?)|(24mm-circular)|(58mm-circular)|(((17x(54|87))|(23x23)|((29|38)(x90)?)|(62x(29|100))|50|54|62)mm))$", re.ASCII | re.IGNORECASE)
pageSizeMatch = pageSizeRegex.match(givenPageSize)
pageSizeCustomRegex = re.compile(r"^custom\.(\d{1,3})x(\d{1,3})$", re.ASCII | re.IGNORECASE)
pageSizeCustomMatch = pageSizeCustomRegex.match(givenPageSize)
if givenPageSize.lower() == "label-wide":
pageSize = "Custom.62x35mm"
elif givenPageSize.lower() == "label-item":
pageSize = "38x90mm"
elif pageSizeMatch:
pageSize = givenPageSize.lower()
elif pageSizeCustomMatch:
width = pageSizeCustomMatch.group(1)
height = pageSizeCustomMatch.group(2)
pageSize = "Custom.{}x{}".format(width, height)
if "SSH_ORIGINAL_COMMAND" in os.environ:
parseGivenOptions()
subprocess.run(["lpr", "-P", "Brother-QL-500", "-o", "MediaType={}".format(mediaType), "-o", "PageSize={}".format(pageSize)])

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from distutils.core import setup
setup(
name = "forcecommand-lpr-wrapper",
version = "0.0.1",
scripts = ["./forcecommand-lpr-wrapper.py"]
)

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{ ... }:
{
networking = {
interfaces.net0 = {
ipv4.addresses = [
{
address = "10.31.208.13";
prefixLength = 25;
}
];
};
defaultGateway = "10.31.208.1";
nameservers = [
"10.31.208.1"
];
};
systemd.network.links."10-net0" = {
matchConfig.MACAddress = "BC:24:11:F2:CF:8F";
linkConfig.Name = "net0";
};
}

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# Sources for this configuration:
# - https://nixos.wiki/wiki/Printing
{ pkgs, lib, ... }:
let
# https://github.com/philpem/printer-driver-ptouch
printer-driver-ptouch = pkgs.stdenv.mkDerivation rec {
pname = "printer-driver-ptouch";
version = "1.7";
src = pkgs.fetchgit {
url = "https://github.com/philpem/printer-driver-ptouch";
rev = "v${version}";
hash = "sha256-3ZotSHn7lERp53hAzx47Ct/k565rEoensCcltwX/Xls=";
};
nativeBuildInputs = [
pkgs.autoreconfHook
pkgs.perl
];
buildInputs = [
pkgs.cups
pkgs.libpng
pkgs.perlPackages.XMLLibXML
pkgs.foomatic-db-engine
];
patches = [
# Add this patch to have the package actually build sucessfully.
# https://github.com/philpem/printer-driver-ptouch/pull/35
(pkgs.fetchpatch {
name = "fix-brother-ql-600.xml.patch";
url = "https://patch-diff.githubusercontent.com/raw/philpem/printer-driver-ptouch/pull/35.patch";
hash = "sha256-y5bHKFeRXx8Wdl1++l4QNGgiY41LY5uzrRdOlaZyF9I=";
})
];
# Used the following as a reference on how to generate the ppd files.
# https://salsa.debian.org/printing-team/ptouch-driver/-/blob/4ba5d2c490ea1230374aa4b0bf711bf77f1ab0c7/debian/rules#L34
postInstall = ''
mkdir -p $out/share/cups
FOOMATICDB=$out/share/foomatic ${pkgs.foomatic-db-engine}/bin/foomatic-compiledb -t ppd -d $out/share/cups/model
rm -r $out/share/foomatic
'';
postPatch = ''
patchShebangs --build foomaticalize
'';
};
forcecommand-lpr-wrapper = pkgs.python3Packages.buildPythonApplication {
name = "forcecommand-lpr-wrapper";
src = ./forcecommand-lpr-wrapper;
propagatedBuildInputs = [
pkgs.cups
];
};
in
{
services.printing = {
enable = true;
drivers = [ printer-driver-ptouch ];
stateless = true;
};
hardware.printers = {
ensurePrinters = [
{
name = "Brother-QL-500";
location = "Z9";
deviceUri = "usb://Brother/QL-500?serial=J8Z249208";
model = "Brother-QL-500-ptouch-ql.ppd";
ppdOptions = {
PageSize = "Custom.62x35mm";
};
}
];
ensureDefaultPrinter = "Brother-QL-500";
};
users.users.print = {
isNormalUser = true;
description = "User for printing via SSH.";
password = "";
};
# PasswordAuthentication being set to false just puts "auth required
# pam_deny.so # deny (order 12400)" for pam.d/sshd, so enable
# PasswordAuthentication to have it not do that.
services.openssh.settings.PasswordAuthentication = lib.mkForce true;
# The following doesn't need to be set in order for empty passwords to work
# apparently:
# security.pam.services.sshd.allowNullPassword = true;
services.openssh.extraConfig = ''
Match User print
PubkeyAuthentication no
AuthenticationMethods none
PermitEmptyPasswords yes
ForceCommand ${forcecommand-lpr-wrapper}/bin/forcecommand-lpr-wrapper.py
Match User *
'';
}

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./config/hosts/forgejo-actions-runner ./config/hosts/forgejo-actions-runner
]; ];
}; };
ptouch-print-server = {
deployment = {
targetHost = "ptouch-print-server.z9.ccchh.net";
targetPort = 22;
targetUser = "colmena-deploy";
tags = [ "thinkcccluster" ];
};
imports = [
./config/common
./config/proxmox-vm
./config/hosts/ptouch-print-server
];
};
}; };
packages.x86_64-linux = { packages.x86_64-linux = {