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A tool that generates custom OpenWRT sysupgrade images

Project description


PyPI version

upenwrt is a tool, in form of a (simple) HTTP server, that generates custom OpenWRT sysupgrade images with all your user-installed packages baked in, on the fly.

It is designed to aid end-user upgrade process (saving you the hassle of reinstalling all your packages by hand), especially if the target device relies on non-default packages for Internet connectivity.


Assuming that the daemon is reachable at http://upenwrt:8000:

curl http://upenwrt:8000/get | sh > /tmp/sysupgrade.img
sysupgrade -v /tmp/sysupgrade.img

Files read by the script:

  • /etc/openwrt_release
  • /tmp/sysinfo/board_name
  • /usr/lib/opkg/status

Command-line arguments and environment variables used by the script:

Command-line argument Environment variable Description Default
--debug $DEBUG enable (more) verbose logging in the script itself not set
--dry-run $DRY_RUN do not call the server, only generate the curl(1) command line not set
--hw-target $TARGET_NAME OpenWRT target name, e. g. ramips/mt7621 overrides $DISTRIB_TARGET of /etc/openwrt_release
--hw-target $TARGET_NAME OpenWRT target name, e. g. ramips/mt7621 overrides $DISTRIB_TARGET of /etc/openwrt_release
--hw-board $BOARD_NAME OpenWRT board name or profile name, e. g. xiaomi,mir3g or mir3g overrides /tmp/sysinfo/board_name
--current-release $RELEASE current (installed) OpenWRT release, e. g. SNAPSHOT overrides $DISTRIB_RELEASE of /etc/openwrt_release
--current-revision $REVISION current (installed) OpenWRT revision, e. g. r10574-273b803623 overrides $DISTRIB_REVISION of /etc/openwrt_release
--packages $PACKAGES list of packages to install into the image, space-separated overrides /usr/lib/opkg/status
--packages-add, --packages-remove $PKGS_ADD, $PKGS_REMOVE lists of packages to add/ignore when installing into the image, space-separated none (supplements /usr/lib/opkg/status)


upenwrt is implemented as a (simple) HTTP server daemon that serves a help page (/), a script (/get) and an API endpoint (/api/get).

The script must be executed on the target device (presumably in the infamous curl | sh pattern) and will collect user-installed package lists and other necessary metadata. The API endpoint is supposed to be called by the script and will return the resulting image in the response body (which will be written on stdout).

daemon usage

The daemon keeps all of its data in its "root directory", henceforth $rootdir.

Inside its $rootdir, the daemon needs:

  • a copy of its static file tree under $rootdir/static (included in upenwrt source tree as root/static)
  • a copy of OpenWRT git repository under $rootdir/repo/openwrt.git (bring your own and fetch regularly, upenwrt will not update it)
  • an empty cache directory $rootdir/cache
  • an empty work directory $rootdir/work

It is advised to put the work directory ($rootdir/work) on tmpfs and the cache directory ($rootdir/cache) on a persistent read-write medium with sufficient storage capacity for a few imagebuilders.

In other words:

mkdir -p /var/lib/upenwrt
cp -r root/static -T /var/lib/upenwrt/static
mkdir -p /var/lib/upenwrt/repo; git clone --bare /var/lib/upenwrt/repo/openwrt.git
mkdir -p /var/lib/upenwrt/cache
mkdir -p /var/lib/upenwrt/work; mount tmpfs -t tmpfs /var/lib/upenwrt/work

python -m upenwrt --rootdir /var/lib/upenwrt --baseurl http://upenwrt:8000 --listen '' --port 8000


The main problem is to separate truly user-installed packages from default packages (which are marked "user" in the opkg database as well), because while it is possible to pass all "user" packages to make image, the default package set is much more prone to change between revisions than user packages.

The obvious idea would be to compare opkg databases between the squashfs and the overlay. However, this will not work if the user already runs an image with some of their packages baked in (or, by extension, if the tool is used twice or more in a row). The only viable idea known to the author is to get a vanilla openwrt image of a matching revision and use its package list as the base.

However, it is infeasible to download and keep vanilla images corresponding to all possible source revisions (as they are, naturally, rotated daily). Instead, the openwrt source tree is downloaded and cached. Upon each request, the source tree is checked out at the revision matching the pre-existing firmware and targetinfo files are generated by calling the buildsystem. "Vanilla" package lists are then extracted from targetinfo files and subtracted from submitted package lists.


This project is distributed under the terms of the GNU Affero General Public License (AGPL), version 3.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License, version 3
as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <>.

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