Add CUPS print server container for Brother HL-4150CDN

2026-10-18 09:16:37 +02:00
commit 6f3162849b
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+schema: spec-driven
+created: 2026-10-17
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+# Design
+
+## Context
+
+See proposal.md for motivation - we need to create a Podman container that runs a CUPS print server for Brother HL-4150CDN. The repo contains the Brother driver packages in `assets/Brother HL-4150CDN/`:
+- `lpr-driver/hl4150cdnlpr-1.1.1-5.i386.deb`
+- `cupswrapper/hl4150cdncupswrapper-1.1.1-5.i386.deb`
+- `installer/linux-brprinter-installer-2.2.6-0.gz` (reference only; we will NOT run it in the build - it is interactive and downloads from the network)
+
+Key observations:
+- Brother drivers are i386 binaries (32-bit ELF). Container needs 32-bit runtime libraries.
+- CUPS wrapper + LPR packages provide PPD, filters, and helper binaries.
+- AirPrint requires CUPS + Avahi/mDNS (DNS-SD).
+- Brother's cups wrapper installs files to /usr/local/Brother/ and may need symlinks into CUPS directories.
+
+## Goals / Non-Goals
+
+**Goals:**
+- Create a Containerfile that builds a working image for Podman
+- Install and configure Brother HL-4150CDN drivers
+- Share printer via IPP with AirPrint discovery
+- Expose ports 631 (CUPS/IPP) and 5353/udp (mDNS)
+- Make it easy to run with podman
+
+**Non-Goals:**
+- Managing multiple printers
+- Custom SSL/TLS configuration for CUPS (use defaults or documented)
+- Persistent CUPS spool/state beyond basic setup
+
+## Decisions
+
+### Base image
+- Use Debian/Ubuntu (or similar) as base to handle .deb packages and 32-bit libs easily. Alternatively Alpine, but Alpine needs musl + 32-bit support can be more complex for prebuilt i386 ELF binaries from Brother. Debian stable is practical.
+
+### Driver installation
+- Use the local `.deb` packages from `assets/Brother HL-4150CDN/` (copied into the build context) and install with `dpkg -i --force-all`. No network download at build time for the driver itself.
+- Do not run the Brother installer script (`linux-brprinter-installer-2.2.6-0.gz`) in the build - it is interactive and downloads packages from download.brother.com.
+- Also need to install brcupsconfpt1 helper if needed - comes with cups wrapper.
+- Run the cups wrapper install logic as per Brother installer (or manually create symlinks).
+
+### CUPS + Avahi + DBus
+- Install cups, avahi-daemon, dbus. Run dbus and avahi-daemon; start cupsd.
+- Configure CUPS to allow remote access/sharing. For containerized setup, typically need to listen on all interfaces and configure sharing.
+
+### Printer configuration
+- Add printer via lpadmin using the Brother PPD. Point to network URI (e.g., ipp://PRINTER_IP/ipp or socket://PRINTER_IP:9100 - depends on printer; HL-4150CDN is network printer).
+- Enable printer sharing and default options.
+
+### Runtime configuration
+- The printer endpoint and advertised name are supplied through environment variables rather than baked into the image, so the same image can be pointed at any HL-4150CDN:
+  - `PRINTER_IP` + `PRINTER_PROTOCOL` (lpd/socket/ipp) derive the device URI.
+  - `PRINTER_URI` overrides the derived URI for full control.
+  - `PRINTER_NAME` sets the CUPS queue name and the DNS-SD/AirPrint advertised name.
+  - `PRINTER_DESCRIPTION` sets the CUPS Description (Info) shown in the web UI.
+- The entrypoint builds the URI and runs lpadmin at startup, then shares the queue.
+
+## Risks / Trade-offs
+
+- [Risk] Brother binaries are 32-bit only → require multiarch libs (libc6:i386, etc.). Increases image size slightly.
+- [Risk] Using .deb packages assumes glibc-based base. If we choose different base, need to ensure compatibility.
+- [Risk] Avahi in container needs --net=host or proper mDNS setup. AirPrint discovery typically works better with host network mode; document this.
+- [Risk] CUPS state (printers.conf, etc.) should be persisted if we want config to survive restarts - may need volumes.
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+# Proposal
+
+## Why
+
+Provide a Podman container that runs CUPS and shares the Brother HL-4150CDN network printer as an AirPrint and IPP printer. Clients should be able to print without installing local printer drivers.
+
+## What Changes
+
+- Create a Containerfile for Podman (based on a Linux distro that supports CUPS and 32-bit binaries)
+- Extract and install Brother driver files (from `assets/Brother HL-4150CDN/` - local .deb packages: `hl4150cdnlpr` and `hl4150cdncupswrapper`) needed for HL-4150CDN
+- Configure CUPS to run in the container and share the network printer
+- Enable mDNS/Avahi for AirPrint discovery
+- Provide minimal runtime configuration (ports 631, 5353/udp) and documentation for running with podman
+- Handle 32-bit dependencies required by Brother i386 binaries
+
+## Capabilities
+
+### New Capabilities
+- `printserver/cups`: Containerized CUPS print server with AirPrint/IPP sharing and Brother HL-4150CDN driver support
+
+### Modified Capabilities
+None
+
+## Impact
+
+- New Containerfile (and possibly supporting files) in repository root
+- Uses Brother driver artifacts in `assets/Brother HL-4150CDN/`
+- Runtime ports: CUPS (631), mDNS (5353/udp) for AirPrint
+- Depends on Avahi/DBus, CUPS, and 32-bit compatibility libs for Brother binaries
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+# Spec Delta
+
+## Purpose
+
+Provide a containerized CUPS print server that shares the Brother HL-4150CDN network printer as an AirPrint and IPP printer so clients can print without installing local printer drivers.
+
+## ADDED Requirements
+
+### Requirement: Container image builds with required dependencies
+The container SHALL include CUPS, Avahi/mDNS, DBus, and required 32-bit runtime libraries to run Brother HL-4150CDN i386 binaries.
+
+#### Scenario: Image contains CUPS
+- **WHEN** the image is built
+- **THEN** CUPS is installed and available at /usr/sbin/cupsd
+
+#### Scenario: Image supports 32-bit Brother binaries
+- **WHEN** the image is built
+- **THEN** required 32-bit libraries are present for the Brother i386 filters
+
+### Requirement: Brother HL-4150CDN driver is installed in container
+The container SHALL install the Brother HL-4150CDN CUPS wrapper, PPD, LPR/filter components from the provided driver artifacts.
+
+#### Scenario: Driver files present
+- **WHEN** the container image is built
+- **THEN** the HL-4150CDN PPD and Brother filters are installed in standard system locations
+
+#### Scenario: CUPS recognizes HL-4150CDN
+- **WHEN** CUPS starts with the driver installed
+- **THEN** CUPS is able to use the HL-4150CDN PPD
+
+### Requirement: Printer is shared and discoverable
+The system SHALL share the Brother HL-4150CDN printer over IPP and make it discoverable via AirPrint (mDNS/DNS-SD) on the container network.
+
+#### Scenario: IPP printer is shared
+- **WHEN** CUPS runs in the container
+- **THEN** the printer is shared via IPP for network clients
+
+#### Scenario: AirPrint discovery
+- **WHEN** Avahi runs alongside CUPS
+- **THEN** the printer is advertised via AirPrint so macOS/iOS clients can discover it without driver installation
+
+### Requirement: Runtime configuration is exposed
+The container SHALL expose CUPS on port 631 and mDNS on UDP port 5353.
+
+#### Scenario: CUPS port exposed
+- **WHEN** the container runs
+- **THEN** port 631 is available for CUPS administration and IPP
+
+#### Scenario: mDNS port exposed
+- **WHEN** the container runs
+- **THEN** UDP port 5353 is available for AirPrint discovery
+
+### Requirement: No client drivers required
+The shared printer SHALL be exposed in a way that client devices can print without installing vendor printer drivers.
+
+#### Scenario: AirPrint compatibility
+- **WHEN** a client discovers the printer via AirPrint
+- **THEN** the client uses native IPP/AirPrint drivers
+
+### Requirement: Printer endpoint and advertised name are configurable at runtime
+The container SHALL accept the network printer address and the advertised printer name through environment variables so the same image can target a different printer or name without rebuilding.
+
+#### Scenario: Printer IP is provided
+- **WHEN** the container is started with `PRINTER_IP` set
+- **THEN** a device URI is derived from that address and the Brother HL-4150CDN queue is created pointing at it
+
+#### Scenario: Printer protocol is selected
+- **WHEN** the container is started with `PRINTER_IP` and `PRINTER_PROTOCOL`
+- **THEN** the device URI uses that protocol (lpd, socket or ipp)
+
+#### Scenario: Full URI override
+- **WHEN** `PRINTER_URI` is set
+- **THEN** it is used as the device URI and `PRINTER_IP` is ignored
+
+#### Scenario: Custom advertised name
+- **WHEN** the container is started with `PRINTER_NAME`
+- **THEN** the CUPS queue uses that name and it is the name advertised via AirPrint/DNS-SD
+
+#### Scenario: Custom CUPS description
+- **WHEN** the container is started with `PRINTER_DESCRIPTION`
+- **THEN** the queue's CUPS Description (Info) is set to that value
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+# Tasks
+
+## 1. Repository initialization
+- [x] 1.1 Initialize jujutsu repository with `jj git init` in repo root and verify `.jj` directory exists
+
+## 2. Container build setup
+- [x] 2.1 Create Containerfile in repository root based on Debian/Ubuntu base image with multiarch support for i386
+- [x] 2.2 Install required system packages: cups, avahi-daemon, dbus, wget/curl, and 32-bit runtime libraries (libc6:i386, libstdc++6:i386, etc.)
+- [x] 2.3 Copy the local Brother driver packages (`assets/Brother HL-4150CDN/lpr-driver/hl4150cdnlpr-1.1.1-5.i386.deb` and `assets/Brother HL-4150CDN/cupswrapper/hl4150cdncupswrapper-1.1.1-5.i386.deb`) into the build context and install them in the container with `dpkg -i --force-all` (verify install reports success)
+- [x] 2.4 Configure CUPS and Brother drivers (symlink PPD/filter files as needed, set up cupsd.conf for container use) and verify files are in correct locations
+- [x] 2.5 Set up startup script to run dbus, avahi-daemon, and cupsd in the container
+- [x] 2.6 Expose ports 631 (CUPS/IPP) and 5353/udp (mDNS) in Containerfile and verify ports are declared
+
+## 3. Printer configuration
+- [x] 3.1 Add logic/config to create and share the Brother HL-4150CDN printer (using lpadmin) with appropriate network URI and PPD; ensure printer is shared for network clients
+- [x] 3.2 Configure Avahi/CUPS for AirPrint advertisement and verify printer will be discoverable
+- [x] 3.3 Add environment-based configuration for the printer address and advertised name (`PRINTER_IP`, `PRINTER_PROTOCOL`, `PRINTER_NAME`, `PRINTER_DESCRIPTION`; `PRINTER_URI` overrides)
+
+## 4. Documentation and testing
+- [x] 4.1 Create or update README with instructions for building and running the container with podman (including host network mode note for mDNS, volume mounts if needed)
+- [x] 4.2 Test container build with podman build and verify image builds successfully
+- [x] 4.3 Test container run and verify CUPS is accessible and printer is shared/discoverable (manual verification)
+- [x] 4.4 Verify `podman run` with `PRINTER_IP` and a custom `PRINTER_NAME` creates the queue at the derived URI and advertises that name