robertgzr / appimage-demo

resources

• https://docs.appimage.org/packaging-guide/

• https://github.com/AppImage/AppImageKit

• https://github.com/AppImageCommunity/AppImageUpdate

• next-gen implementation of appimagespec?: https://github.com/probonopd/go-appimage

internals

manual creation of appimage needs spec-complicant (contains AppRun exectuable) squashfs filesystem appeneded to their runtime:

mksquashfs Your.AppDir Your.squashfs -root-owned -noappend
cat runtime >> Your.AppImage
cat Your.squashfs >> Your.AppImage

The runtime elf binary contains empty sections, that are used to embed metadata:

• update information
• md5 digest
• sha256 signature
• signing key

updating

• appimageupdate[tool] supports consuming updates from static file server, github releases: https://github.com/AppImage/AppImageSpec/blob/master/draft.md#update-information

signing

• https://docs.appimage.org/packaging-guide/optional/signatures.html
• using local gpg key: appimagetool --sign --sign-key <KEY_ID> <SOURCE>
• embeds the signature into ELF section .sig_key
• is not part of the spec
  • AppImage/AppImageSpec#29
  • AppImage/AppImageSpec#30
• has issues with gpg keys containing subkeys: AppImage/AppImageKit#1010

metadata

• https://docs.appimage.org/packaging-guide/optional/appstream.html
• https://www.freedesktop.org/software/appstream/metainfocreator
• https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html

in container

$ docker build -t appimage-demo -f Dockerfile .
$ docker run --rm -it \
  --mount=type=bind,src=$PWD,target=/src \
  --mount=type=volume,src=appimage-tmp,target=/tmp \
  --workdir=/src \
  appimage-demo \
  make bundle

demo app

usage: demo

  -U  self-update
  -v  print information
  -h  show this help