pup | Pluggable Micro Packager

pup is (in the early stages of becoming) a packaging tool for Python GUI programs.

Fundamentally, its raison d'être is producing macOS and Windows native packages for distributing the Mu Editor to Python beginners around the world. As a by-product of that, it may very likely be effective at packaging generic Python written GUI programs. If that ever is the case, then great. Otherwise, that's fine too.

The purpose, again, is to package Mu Editor for macOS and Windows distribution.

Capabilities

The current version of pup, while still very limited and somewhat exploratory, can package, at least, the Mu Editor and puppy into distributable:

• Windows MSI installer files

  Minimally featured, user-installable, with an optional License Agreement GUI, adding an entry to the Windows Start Menu, with an optional custom icon.

  The packaged binary files can be signed, as well as the final MSI file.

  As a side-effect of the process, a relocatable directory holding the aplication is produced, paving the way for the creation "portable" Windows applications.

• macOS DMG files

  Holding the relocatable .app application bundle, with an optional custom icon, properly signed and notarized as required for distribution,

  Including an optional License Agreement GUI and custom volume icon.

• Linux AppImage files

  Preliminary support: limited to Python 3.8 on x86_64 systems, with the Desktop Entry's Categories hard-coded to "Education".

As of this writing, pup should be able to package any Python GUI application that:

• Runs on Python 3.7, on macOS or Windows.
• Runs on Python 3.8, on macOS, Linux or Windows.
• Is pip-installable (no need to be on PyPI, though).
• Is launchable from the CLI with python -m <launch-module>.

No specific efforts have been put forth to ensure that that is the case, however, so YMMV.

Installation

pup is distributed via PyPI. Install it with:

$ pip install pup

Generic Usage

To package an application, run:

$ pup package <pip-install-src>

Where:

• <pip-install-src> is the argument in the pip install <pip-install-src> command to install the application on the local Python environment.

  In general, if it's pip-installable then it's probably pup-packageable.

This usage pattern assumes that the application GUI is launchable with python -m <name>, where <name> is extracted from the metadata of a wheel created from <pip-install-src>. If that is not the case, pup can be told otherwise. Read on.

When completed, the final distributable artifact will be placed under ./dist/.

Packaging Options

• Use --launch-module=<name> to set the module name that should be used to launch the application GUI, as with the python -m <name> command.

• Use --nice-name=<name> to set a "nice name" for the application to be used used throughout the packaging process: in file and directory names, for macOS's application bundle and DMG file names, and for the Windows Start Menu entry.

  When omitted, that name is obtained from the metadata of a wheel created from <pip-install-src>, that very often does not match the exact product spelling, as communicated to end-users.

• Use --icon-path=<icon-path> to include a custom icon in the packaging process.

  On macOS the given file can be either an ICNS or PNG file which will be used as the icon for both the packaged application bundle and the DMG file volume icon.

  On Linux the file should be a PNG file which will be used as the icon for the running application.

  On Windows the file can be either an ICO or PNG file which will be used on the Windows Start Menu entry and on the Windows Programs and Features listing.

• Use --license-path=<license-path> to bundle the given license text and require users to accept it before installation (not currently supported on Linux AppImage).

  The given <license-path> must be an ASCII-encoded text file.

• Use --launch-pyflag=<flag> to override the default -I Python launch flag (repeat for each flag to be used or set <flag> to the empty string to use none).

Signing

Signing is optional and varies slightly between platforms.

pup will only sign the application for distribution when all of the following conditions are true. On macOS, pup will also complete the Apple required notarization process: for that, the packaging system must be online and able to connect to Apple's notarization services over the internet.

macOS

• XCode 10.3 or later must be installed -- the Command Line Tools are not enough.
• The following environment variables must be set:
  • PUP_SIGNING_IDENTITY: 10-digit identifier on the Apple Developer Certificate.
  • PUP_NOTARIZE_USER: email address for the Apple Developer Account.
  • PUP_NOTARIZE_PASSWORD: Application Specific Password.

Windows

• The Windows SDK must be installed, providing the signtool.exe utility.
• The following environment variable must be set:
  • PUP_SIGNING_IDENTITY: cname of the code signing certificate.

Behaviour Notes

In the first run, pup downloads one or more files, which are cached locally for later use:

• A relocatable Python Runtime from the Python Build Standalone project.
• On Windows, the WiX toolset, used to create MSI files.

pup logs its progress to STDERR, with fewer per-event details when it's a TTY. The logging level defaults to INFO and can be changed with either the --log-level CLI option, or by setting the PUP_LOG_LEVEL environment variable.

Other than the locally cached files, pup creates files under:

• ./build/pup/ containing all intermediate artifacts..
• ./dist/ where the final distributable artifact is delivered..

---

Packaging the Mu Editor on Windows

Requirements for signing:

• The Windows SDK must be installed.
• A code signing certificate must be available under Windows' certmgr utility.

Run:

> set PUP_SIGNING_IDENTITY=<signer>

Where:

• <signer> is the cname attribute of the code signing certificate.

Then, assuming the current working directory is Mu Editor's repository root, run:

> pup package
      --launch-module=mu
      --nice-name="Mu Editor"
      --icon-path=.\package\icons\win_icon.ico
      --license-path=.\LICENSE
      .

Note:

• The command is line-wrapped for readability, but must be input as a single line.
• One of the last packaging stages is signing.
• It will take a while as there are many files to be signed, but progress is continuously displayed, with the defaul log level.

Once completed:

• The resulting MSI file will be ./dist/Mu Editor <version>.msi.
• A by-product of that is the ./build/pup/Mu Editor <version>/ relocatable directory, containing a GUI-clickable script that launches Mu. Creating a ZIP file from it for distribution results in a minimally working "portable" Windows application.

Packaging the Mu Editor on macOS

Requirements for signing and notarization:

• Must have XCode 10.3 or later installed.
• Must have an Apple Developer Certificate -- see this article's step 4, for guidance.
• Must create an Application Specific Password -- see this article, for guidance.

Run:

$ export PUP_SIGNING_IDENTITY=<signer>
$ export PUP_NOTARIZE_USER=<user>
$ export PUP_NOTARIZE_PASSWORD=<asp>

Where:

• <signer> is the 10-digit identifier on your Apple Developer Certificate's cname.
• <user> is the email address associated to you Apple Developer Account.
• <asp> is the Application Specific Password.

Then, assuming the current working directory is Mu Editor's repository root, run:

$ pup package \
      --launch-module=mu \
      --nice-name="Mu Editor" \
      --icon-path=./package/icons/mac_icon.icns \
      --license-path=./LICENSE \
      .

Note:

• One of the last packaging stages is notarization.
• It will take a while -- no less than 3 minutes, IME, sometimes 10-15 minutes.
• The logged messages should help understand that the "thing" is not hung.
• Just be patient, I guess! :)

Once completed:

• The resulting DMG file will be ./dist/<name> <version>.dmg.
• A by-product of that is the ./build/pup/Mu Editor.app/ relocatable application bundle. Archiving it into a ZIP file, for distribution, should be perfectly fine.

More

To learn more about pup refer to the online documentation: at this early stage, it is mostly a collection of thoughts and ideas around behaviour, requirements, and very very rough internal design.

Development moves forward on GitHub at https://github.com/mu-editor/pup/.

Thanks

• To Nicholas Tollervey, for the amazing Mu Editor.
• To the Mu Editor contributors I've been having the privilege of working more directly with, Carlos Pereira Atencio, Martin Dybdal, and Tim Golden, as well as the others whom I haven't met yet but whose contributions I highly respect.
• To Russell Keith-Magee, for the inspiring BeeWare project and, in particular, for briefcase that being used as the packaging tool for Mu on macOS as of this writing, serves as a great inspiration to pup.
• To Gregory Szorc, for the incredible Python Standalone Builds project, on top of which pup packages redistributable Python GUI applications.
• To Donald Stufft, for letting us pick up the pup name in PyPI.
• To Glyph Lefkowitz, for the very useful, high quality Tips And Tricks for Shipping a PyGame App on the Mac article, and for his generous hands-on involvement in the first-steps of pup's take on the subject in this issue.
• To Alastair Houghton, for dmgbuild, that pup uses to create macOS DMG files.
• To the WiX Toolset developers, maintainers, contributors, and sponsors: not sure how pup would go about building Windows MSI installers without it.

About

pup is in the process of being created by Tiago Montes, with the wonderful support of the Mu development team.