Make appimagetool run on Alpine/musl

[probonopd]

Initial support is available, this allows us to package musl-based applications into AppImages:

#############################################
# Download and extract minimal Alpine system
#############################################

wget http://dl-cdn.alpinelinux.org/alpine/edge/releases/x86_64/alpine-minirootfs-3.11_rc1-x86_64.tar.gz
mkdir -p ./miniroot
cd ./miniroot
tar xf ../alpine-minirootfs-*.tar.gz
cd -

#############################################
# Prepare chroot
#############################################

sudo mount -o bind /dev miniroot/dev
sudo mount -t proc none miniroot/proc
sudo mount -t sysfs none miniroot/sys
sudo cp -p /etc/resolv.conf miniroot/etc/
sudo chroot miniroot /bin/sh <<\EOF

#############################################
# Now inside chroot
#############################################

# Upgrade to Edge, the rolling Alpine release (if we don't have it already)
sed -i -e 's/v[[:digit:]]\..*\//edge\//g' /etc/apk/repositories
apk upgrade --update-cache --available

# Install dependencies and download appimagetool
apk add wget squashfs-tools desktop-file-utils curl appstream libc6-compat
wget -c https://raw.githubusercontent.com/probonopd/uploadtool/master/upload.sh -O uploadtool
chmod +x uploadtool 
wget https://github.com/AppImage/AppImageKit/releases/download/continuous/runtime-x86_64
wget http://192.168.0.14/home/me/go/src/github.com/probonopd/go-appimage/src/appimagetool/appimagetool ; chmod +x appimagetool # Not the AppImage for now
export PATH=$(readlink -f .):$PATH

# Install patchelf 0.9 because 0.10 cripples files
apk add  --no-cache --repository http://dl-cdn.alpinelinux.org/alpine/v3.10/main/ patchelf=0.9-r2
# or from source 
apk add alpine-sdk bash util-linux wget autoconf gettext automake
wget https://github.com/NixOS/patchelf/archive/0.9.tar.gz # 0.10 cripples my files
tar xf *.tar.gz 
cd patchelf-*/
./bootstrap.sh
./configure --prefix=/usr
make -j$(nproc)
sudo make install
cd -

# Get the application to be packaged
apk add kcalc
apk fetch kcalc
export VERSION=$(ls kcalc-*.apk | cut -d - -f 2)
mkdir -p appdir ; cd appdir
tar xfv ../kcalc*.apk
cd -

./appimagetool -s deploy appdir/usr/share/applications/*.desktop

./appimagetool appdir/

#############################################
# Exit chroot and clean up
#############################################

exit
EOF
sudo umount miniroot/proc miniroot/sys miniroot/dev

[probonopd]

So appimagetool itself is running on musl based systems like Alpine, and the resulting AppImages (that bundle everything) can run on glibc-based systems.

We are now blocked by AppImage/AppImageKit#1015.

[probonopd]

@s-zeid just confirmed that the appimagetool AppImage using the experimental static AppImage runtime works on Alpine Linux.

But appimaged is dynamically linked. Why? Can we make it static?

[probonopd]

Well, appimagetool runs on Alpine but not in -s deploy mode yet, because it assumes to be working on glibc. For musl, it's probably a matter of leaving a few things away?

VERSION=1 ./appimagetool-730-x86_64.AppImage -s deploy ./xterm.AppDir/usr/share/applications/
xterm.desktop 
AppDir path: xterm.AppDir
Exec= key contains: xterm
Icon= key contains: xterm-color_48x48
2022/11/06 20:14:46 Gathering all required libraries for the AppDir...
2022/11/06 20:14:46 len(allELFsUnderPath): 1
2022/11/06 20:14:46 libraryLocations: [xterm.AppDir/usr/bin /usr/lib64 /lib64 /usr/lib /lib /usr/lib/x86_64-linux-gnu/libfakeroot /usr/local/lib /usr/local/lib/x86_64-linux-gnu /lib/x86_64-linux-gnu /usr/lib/x86_64-linux-gnu /lib32 /usr/lib32]
2022/11/06 20:14:46 len(allELFs): 25
2022/11/06 20:14:46 Deploying /lib/ld-musl-x86_64.so.1...
2022/11/06 20:14:46 Patching ld-linux...
2022/11/06 20:14:46 Determining gconv (for GCONV_PATH)...
ERROR Could not deploy the interpreter: did not find gconv
/ # 

[probonopd]

Disabled the fatal error on that check for now, and as a result I am able to deploy applications from Alpine Linux with ``-s deploy`.

Hence closing. Further improvements can be addressed in separate tickets.

References:

• find the way to package DOS programs/games dosemu2/dosemu2#2133
• https://github.com/probonopd/doesemu2-factory/blob/c34ada32831f8f5ff6acfab87b4821825d58f99b/build.sh