Creating OpenWrt as a Docker Image

Installing Docker

Following Docker’s official documentation, first uninstall all conflicting packages. apt-get may indicate some packages are not installed.

Ubuntu:

for pkg in docker.io docker-doc docker-compose docker-compose-v2 podman-docker containerd runc; do sudo apt-get remove $pkg; done

Debian:

for pkg in docker.io docker-doc docker-compose podman-docker containerd runc; do sudo apt-get remove $pkg; done

Set up Docker’s apt repository:

Ubuntu:

# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

# Add the repository to Apt sources:
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

Debian:

# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

# Add the repository to Apt sources:
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

Install Docker:

sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Building

I won’t go into detail about compilation. I use GitHub cloud compilation. After completion, you can find the openwrt-x86-64-generic-rootfs.tar.gz file in the Release section. Download it to create a Docker image.

Creating a Docker Image

This step can be fully integrated into GitHub Actions, but for now I’m doing it manually and will update GitHub Actions later.

Create Dockerfile:

FROM scratch
ADD openwrt-x86-64-generic-rootfs.tar.gz /
WORKDIR /
CMD ["/sbin/init"]

Build Docker image:
```
docker build -t openwrt:latest .
```

Deploying on Linux

Due to macvlan’s limitations on communication between host and Docker containers, I was unable to ping the OpenWrt IP address after running these commands. The following is just for personal reference.

Assuming my lan interface is enp0s1, enable promiscuous mode:
```
ip link set enp0s1 promisc on
```

Set up macvlan:

docker network create -d macvlan \
    --subnet=192.168.2.0/24 \
    --gateway=192.168.2.1 \
    -o parent=enp0s1 \
    wrt_lan

Start the OpenWrt image:

docker run -d --name openwrt \
    --net wrt_lan \
    --ip 192.168.2.66 \
    --privileged \
    openwrt /sbin/init

Enter the OpenWrt container and change the LAN interface to a static IP address:

docker exec -it openwrt sh

Then edit /etc/config/network:

vi /etc/config/network

Change it to:

config interface 'lan'
        option type 'bridge'
        option ifname 'eth0'
        option proto 'static'
        option netmask '255.255.255.0'
        option ip6assign '60'
        option ipaddr '192.168.2.66'	# OpenWrt IP address
        option gateway '192.168.2.1'	# Main router IP
        option dns '192.168.2.1'		# Main router IP

Restart the OpenWrt network service:
```
/etc/init.d/network restart
```

Installing Docker#

Building#

Creating a Docker Image#

Deploying on Linux#

Installing Docker

Building

Creating a Docker Image

Deploying on Linux