Build OpenWrt images in a Docker container. This is sometimes necessary when building OpenWrt on the host system fails, e.g. when some dependency is too new. The docker image is based on Debian 10 (Buster).

Build tested:

• Openwrt-24.10.0
• Openwrt-23.05.4
• OpenWrt-22.03.5
• OpenWrt-21.02.2
• OpenWrt-19.07.8
• OpenWrt-18.06.9

A smaller container based on Alpine Linux is available in the alpine branch. But it does not build the old LEDE images.

• Docker installed
• running Docker daemon
• build Docker image:

git clone https://github.com/mwarning/docker-openwrt-builder.git cd docker-openwrt-builder docker build -t openwrt_builder .

Now the docker image is available. These steps only need to be done once.

Create a build folder and link it into a new docker container:

mkdir ~/mybuild docker run -v ~/mybuild:/home/user -it openwrt_builder /bin/bash

In the container console, enter:

git clone https://git.openwrt.org/openwrt/openwrt.git cd openwrt ./scripts/feeds update -a ./scripts/feeds install -a make menuconfig make -j4

After the build, the images will be inside ~/mybuild/openwrt/bin/target/.

OpenWrt requires a case-sensitive filesystem while MacOSX uses a case-insensitive filesystem by default.

Create a sparse disk image (to limit space usage):

mkdir ~/Documents/openwrt cd ~/Documents/openwrt hdiutil create -size 64g -fs "Case-sensitive HFS+" -type SPARSEBUNDLE -volname openwrt-dev-env openwrt-dev-env.dmg hdiutil attach openwrt-dev-env.dmg

Then run:

docker run -v /Volumes/openwrt-dev-env:/home/user -it openwrt_builder /bin/bash

Inside the container shell create a image file that will be formatted in ext4 then mounted (thanks to HowellBP for the inspiration):

cd /home/user # not really needed dd if=/dev/zero of=ext4openwrtfs.img bs=1G count=0 seek=60 # set "seek=" to however many gigabytes you want, always less than the created dmg image mkfs.ext4 ext4openwrtfs.img # create filesystem mkdir ./openwrt-fs # create mount folder losetup -fP --show ext4openwrtfs.img # this will return a /dev/loop ID, e.g. /dev/loop1, change line below with the correct one sudo mount /dev/loop1 ./openwrt-fs # mount support folder sudo chown -R user:user ./openwrt-fs # change ownership to user cd ./openwrt-fs # $(pwd) should be /home/user/openwrt-fs

At this point you can proceed with the same commands of the Linux usage:

git clone https://git.openwrt.org/openwrt/openwrt.git # repo will be in /home/user/openwrt-fs/openwrt cd openwrt ./scripts/feeds update -a ./scripts/feeds install -a make menuconfig make -j4 # adapt to the number of cores you want to use 

After the build, the images will be inside /home/user/openwrt-fs/openwrt/bin/target/ in the container, inside the .img file. To export them to your Mac you need to copy/move them in /home/user then you'll be able to access them from outside the container, in /Volumes/openwrt-dev-env/

(Source)

TODO

Other, but very similar projects:

• openwrt-docker Official Docker containers to build OpenWrt!
• openwrt-imagebuilder-action
• docker-openwrt-buildroot
• openwrt-docker-toolchain