AppBundler 1.0 - Bundle your Julia application and beyond

Janis Erdmanis
janiserdmanis.org

About Me

• Physics PhD
• Julia user since v0.3.4
• Presenting at EVoteID this year (hobby)

A few years ago, I wanted to build a prototype
for an e-voting system peacefounder.org

That led me to a deployment challenge:

How do you deploy user-facing GUI applications written in Julia?

And that's how AppBundler started.

The Ultimate Solution?

curl -L https://trust.me/install.sh | sh

Why Do We Want Installers?

• User-friendly experience
  • Download → install → run
• Clean: Install and uninstall without leaving a mess
• Native: Icons, shortcuts, file associations, OS integration, performance
• Sandboxing & Security
  • Limit application permissions
  • Not as safe as a web page in a browser — but the same spirit

Why is this so hard?

1. Platform-specific tooling
   Vendor SDKs, packaging utilities, signing tools
2. Platform-specific behavior
   Installation, launch, runtime layout, permissions
3. Application dependencies
   What is bundled? What is shared? What is already on the system?
4. Distribution & trust
   Signing, notarization, approval, certificates

Demo - Counting Words

module CmdApp

import AppEnv

function (@main)(ARGS::Vector{String})
    AppEnv.init() # initialize runtime environment

    # application logic
    filename = only(ARGS)
    println("$filename: $(word_count(filename)) words")

    return 0
end

export main

end

If your Julia application exposes @main and can be launched with julia --project=. -m MyApp, it is ready to bundle:

appbundler build ./examples/CmdApp --build-dir=build --selfsign

What AppBundler provides

1. Relocatable application bundles — PkgImages · SysImages · JuliaC
2. Native package formats — MSIX · DMG · Snap (sandboxing)
3. Reproducible packaging toolchain — open source, BinaryBuilder + Yggdrasil, no platform-specific toolchain to maintain
4. Sensible defaults — native configuration for targeted customization

Beyond Julia @main

AppBundler isn't limited to one application structure

• Julia applications — the standard @main entry point
• Full Julia distributions — Jumbo Julia
• Other build systems — applications can use their own build process

MSIX

Microsoft tooling

StagingDir → MakeAppx → SignTool → MyApp.msix

• Windows SDK/tooling
• Licensing prevents redistribution with AppBundler

AppBundler

StagingDir → msixpack → osslsigncode → MyApp.msix

• Open-source, redistributable tooling
• Cross-compilable with BinaryBuilder

MSIX — What's inside the package?

AppBundler assembles this StagingDir/ before creating the .msix.

• AppxManifest.xml — identity, entry point, capabilities
• resources.pri — MSIX resource index (fixes ugly icon rendering)
• Assets/ — application icons
• Msix.AppInstaller.Data/MSIXAppInstallerData.xml — installer config
• MyApp.exe — application launcher

AppBundler changes MyApp.exe to the Windows GUI subsystem after compilation. For GUI applications, this currently leaves a zombie console process.

Sandboxing is configured through AppxManifest.xml. The application also requires the UCRT runtime.

DMG

Apple tooling

MyApp.app → codesign → hdiutil → codesign → notarytool → stapler

AppBundler

MyApp.app → rcodesign → xoriso → dmg → rcodesign -notarize

• dmg from libdmg-hfsplus
• Open-source, redistributable tooling
• Cross-compilable with BinaryBuilder

DMG — What's inside the app?

AppBundler assembles the MyApp.app bundle before creating the .dmg:

• Contents/MacOS/MyApp - application launcher
• Contents/Libraries/main - binary stub reference
• Contents/Info.plist- application metadata
• Contents/Resources/icon.icns - application icon
• ../DS_Store - controls the installer's appearance

The launcher must be a native binary for code signing. Sandboxing is configured through Entitlements.plist and incorporated into the signed launcher.

Snap

Snapcraft

snapcraft.yaml → snapcraft → MyApp.snap

• Open-source, but does not cross compile
• Wants to do compilation for you

AppBundler

StagingDir → mksquashfs → MyApp.snap

• Open-source, redistributable tooling
• Cross-compilable with BinaryBuilder

Snap — What's inside the package?

AppBundler assembles the StagingDir/ before creating the .snap:

• snap/snap.yaml — package metadata and configuration
• bin/MyApp — application launcher
• meta/icon.png — application icon
• meta/gui/MyApp.desktop — desktop integration
• meta/hooks/configure — configuration hook

Asset referencing

Compiled code doesn't know it's been moved.

• @__DIR__ → hardcoded build path → unrelocatable
• pkgdir(@__MODULE__)/assets → works with PkgImages + SysImage
• JuliaC → sources gone → pkgdir fails

Fix: ship an asset index; AppEnv.init() repopulates Base.pkgorigins

Asset trimming

Sysimage and JuliaC bundles don't need the sources — only the assets. We can select only the assets we need in LocalPreferences.toml:

[AppEnv]
assets = ["LICENSE"]

[QMLApp]
assets = ["src/App.qml"]

[AppBundler]
juliaimg_selective_assets = true
# Other AppBundler options

Challenges

Julia does not cross compile

Install GitHub action script:

AppBundler.install_github_workflow()

and bunlde installers with macos-latest-x86_64, macos-latest-aarch64, ubuntu-latest-x86_64, ubuntu-24.04-arm-aarch64, windows-latest runners.

Codesigning certificates are expensive

Until then:

curl -L https://trust.me/install.sh | sh

The install.sh script can bootstrap trust of the bundle signer. The app then installs through the normal platform packaging path.

Future Work

• Flatpak support
• RPM and DEB targets
• Polish — icons, template management, CLI output
• Drop Quaternions.jl from the dependency chain
• Self-hosted CLI — no Python ds_store dependency
• Generic API for bundling projects in other languages