How to create an AppImage

AppImage is a brilliant way to have executable linux apps to every distro, without the need of re-packaging or re-build them. Without getting into too many details, it uses FUSE (Filesystem in Userspace) and SquashFS to bundle the app into one file.

AppImages require FUSE to run. Filesystem in Userspace (FUSE) is a system that lets non-root users mount filesystems.

So here are my personal notes on how to create Mozilla Firefox 68.3.0esr binary archive to an AppImage file.

download

Let’s begin by gathering all necessaries files

export VERSION=68.3.0esr

curl -sLO https://github.com/AppImage/AppImageKit/releases/download/continuous/appimagetool-x86_64.AppImage

curl -sL https://ftp.mozilla.org/pub/firefox/releases/$VERSION/linux-x86_64/en-US/firefox-$VERSION.tar.bz2 | tar xjf -

configuration files

we need 3 files, under the firefox directory

• AppRun (executable shell script)
• Icon (.png,.svg,.xpm)
• firefox.desktop (freedesktop.org desktop file)

AppRun

this is our guide, this file will start our application inside the AppImage mount.

#!/bin/sh
cd "$(dirname "$0")"
exec ./firefox "$@"

or

cat > firefox/AppRun <<EOF
#!/bin/sh
cd "\$(dirname "\$0")"
exec ./firefox "\$@"

EOF

Dont forget to make it executable

chmod +x firefox/AppRun

Icon

There is an image within firefox directory that we can use as firefox icon:

./firefox/browser/chrome/icons/default/default128

firefox.desktop

for more info check here: Desktop Entry Specification

[Desktop Entry]
Categories=Network;WebBrowser;
Icon=/browser/chrome/icons/default/default128
Name=Mozilla Firefox
Terminal=false
Type=Application
Version=1.0

or

cat > firefox/firefox.desktop <<EOF
[Desktop Entry]
Categories=Network;WebBrowser;
Icon=/browser/chrome/icons/default/default128
Name=Mozilla Firefox
Terminal=false
Type=Application
Version=1.0
EOF

In the Icon attribute, it must be an absolute path, not relative.

Perms

Give execute permission to appimagetool

chmod +x appimagetool-x86_64.AppImage

Build your AppImage

./appimagetool-x86_64.AppImage --no-appstream firefox/

Mozilla Firefox

if everything is okay, you will see this:

ls -l Mozilla_Firefox-x86_64.AppImage

and you can run it !

./Mozilla_Firefox-x86_64.AppImage

if you want to run a specific profile:

./Mozilla_Firefox-x86_64.AppImage --profile $(pwd)/.mozilla/firefox/ichznbon.test/

Mount

When you are running your AppImage, you will notice that there is a new mount point in our system (fusermount)

$ mount | grep -i firefox
Mozilla_Firefox-x86_64.AppImage on /tmp/.mount_MozillshcmPB type fuse.Mozilla_Firefox-x86_64.AppImage (ro,nosuid,nodev,relatime,user_id=347,group_id=347)

and if you look really careful, you will see that it is mounted under /tmp/ !

$ ls /tmp/.mount_MozillshcmPB
application.ini     firefox          icons               libmozsqlite3.so  libplc4.so       minidump-analyzer     Throbber-small.gif
AppRun              firefox-bin      libfreeblpriv3.chk  libmozwayland.so  libplds4.so      omni.ja               updater
browser             firefox-bin.sig  libfreeblpriv3.so   libnspr4.so       libsmime3.so     pingsender            updater.ini
chrome.manifest     firefox.desktop  liblgpllibs.so      libnss3.so        libsoftokn3.chk  platform.ini          update-settings.ini
crashreporter       firefox.sig      libmozavcodec.so    libnssckbi.so     libsoftokn3.so   plugin-container
crashreporter.ini   fonts            libmozavutil.so     libnssdbm3.chk    libssl3.so       plugin-container.sig
defaults            gmp-clearkey     libmozgtk.so        libnssdbm3.so     libxul.so        precomplete
dependentlibs.list  gtk2             libmozsandbox.so    libnssutil3.so    libxul.so.sig    removed-files

That’s it !

Your first AppImage bundle linux package.

Docker Notes

FUSE · AppImage/AppImageKit Wiki · GitHub

docker run --cap-add SYS_ADMIN --cap-add MKNOD --device /dev/fuse:mrw --rm -ti ubuntu:18.04 bash

 apt-get update

 apt-get -y install curl libfuse2 file 

 export VERSION=68.3.0esr

 curl -sLO https://github.com/AppImage/AppImageKit/releases/download/continuous/appimagetool-x86_64.AppImage

 curl -sL https://ftp.mozilla.org/pub/firefox/releases/$VERSION/linux-x86_64/en-US/firefox-$VERSION.tar.bz2 | tar xjf -

 cat > firefox/AppRun <<EOF
#!/bin/sh
cd "\$(dirname "\$0")"
exec ./firefox "\$@"
EOF

 cat > firefox/firefox.desktop <<EOF
[Desktop Entry]
Categories=Network;WebBrowser;
Icon=/browser/chrome/icons/default/default128
Name=Mozilla Firefox
Terminal=false
Type=Application
Version=1.0
EOF

 chmod +x appimagetool-x86_64.AppImage

 ./appimagetool-x86_64.AppImage --no-appstream firefox/

appimagetool, continuous build (commit 64321b7), build 2111 built on 2019-11-23 22:20:53 UTC
WARNING: gpg2 or gpg command is missing, please install it if you want to create digital signatures
Using architecture x86_64
/firefox should be packaged as Mozilla_Firefox-x86_64.AppImage
Deleting pre-existing .DirIcon
Creating .DirIcon symlink based on information from desktop file
Generating squashfs...
Parallel mksquashfs: Using 8 processors
Creating 4.0 filesystem on Mozilla_Firefox-x86_64.AppImage, block size 131072.
[===========================================================================================================================|] 1583/1583 100%

Exportable Squashfs 4.0 filesystem, gzip compressed, data block size 131072
    compressed data, compressed metadata, compressed fragments,
    compressed xattrs, compressed ids
    duplicates are removed
Filesystem size 71064.05 Kbytes (69.40 Mbytes)
    36.14% of uncompressed filesystem size (196646.16 Kbytes)
Inode table size 5305 bytes (5.18 Kbytes)
    60.46% of uncompressed inode table size (8774 bytes)
Directory table size 1026 bytes (1.00 Kbytes)
    54.78% of uncompressed directory table size (1873 bytes)
Number of duplicate files found 3
Number of inodes 81
Number of files 67
Number of fragments 7
Number of symbolic links  1
Number of device nodes 0
Number of fifo nodes 0
Number of socket nodes 0
Number of directories 13
Number of ids (unique uids + gids) 1
Number of uids 1
    root (0)
Number of gids 1
    root (0)
Embedding ELF...
Marking the AppImage as executable...
Embedding MD5 digest
Success

Please consider submitting your AppImage to AppImageHub, the crowd-sourced
central directory of available AppImages, by opening a pull request
at https://github.com/AppImage/appimage.github.io

final notes:

 du -h Mozilla_Firefox-x86_64.AppImage
70M Mozilla_Firefox-x86_64.AppImage

 ls -l Mozilla_Firefox-x86_64.AppImage
-rwxr-xr-x 1 root root 72962088 Dec 26 21:55 Mozilla_Firefox-x86_64.AppImage

 file Mozilla_Firefox-x86_64.AppImage
Mozilla_Firefox-x86_64.AppImage: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/l, for GNU/Linux 2.6.18, stripped

 ldd Mozilla_Firefox-x86_64.AppImage
    not a dynamic executable