My Raspberry Pi 3 died. It was used for running Plex server. It was running inside docker before the Pi died. I was looking for replacement. I looked into my basement and I found two Google_Nexus_5_(lg-hammerhead) phones. Then the story began…
Prerequisites
- you are fairly familiar with how flashing works, e.g. fastboot stuff.
- you’ve already running postmarketos on your phone
- you know what docker is
- you know that you are probably gonna remove all the fancy UIs from your phone, and switch to postmarketos-ui-fbkeyboard or some console only mode
- you’d better have a LAN connection on your phone rather than wifi
Steps
I can only prove this is working on my phones for now.
1. Edit kernel config
NOTE: before you make any change to kernel, always backup ~/.local/var/pmbootstrap/cache_git/pmaports/main/linux-postmarketos-qcom-msm8974/config-postmarketos-qcom-msm8974.armv7
Run
pmbootstrap kconfig edit postmarketos-qcom-msm8974
where qcom-msm8974 is for my Nexus 5. You need to figure out what’s for your phone.
You have 2 options to learn what to set when configuring the kernel:
- follow https://wiki.gentoo.org/wiki/Docker#Kernel (which doesn’t really apply to kernel 5.9 but I made it)
- run https://raw.githubusercontent.com/moby/moby/master/contrib/check-config.sh
You can see the changes I made to my kernel config at https://gitlab.com/tigerinus/pmaports/-/commit/d4c1ad862f5485fd9a7577e59b95e97da1b988ae
BTW – I’ve got a Ugreen USB 2.0 network adapter hooked, so I took the chance and selected
Device Drivers => Network device support => <*> USB Network Adapters => <*> ASIX AX88xxx Based USB 2.0 Ethernet Adapters
2. Build the kernel
pmbootstrap build linux-postmarketos-qcom-msm8974 --force
I had to add --force otherwise it won’t build.
If everything is successful, you should find something like below
~/.local/var/pmbootstrap/packages/edge/armv7/linux-postmarketos-qcom-msm8974-5.9.0_rc4-r0.apk
3. Install the kernel
Get the linux-postmarketos-qcom-msm8974-5.9.0_rc4-r0.apk copied onto your phone and do
sudo apk add -u linux-postmarketos-qcom-msm8974-5.9.0_rc4-r0.apk
Just in case, I also copied /boot/boot.img-postmarketos-qcom-msm8974 to local as boot.img, boot to bootloader and did
fastboot flash boot boot.img
Reboot the phone and run check-config.sh again to see if anything missing. My experience is you don’t need everything enabled.
4. Install docker
Boot to your phone, assuming you have a pretty good internet connection, then do
sudo apk add docker
Not only this installs docker, but also an important service containerd.
5. Get docker daemon running
Run
sudo service docker start
We are not there yet. This first-time boot is for creating files, directories, group it needs. The docker command won’t work because of couple things that have to happen at boot time below.
DO NOT make docker to start on boot or you will get “can’t load program: function not implemented: unknown.” error.
BTW – If you hate doing sudo docker... everytime, you can optionally add yourself to docker group by
sudo vi /etc/group
Now reboot so at least containerd service is effective, in terms of automatically mounting cgroup2 to /sys/fs/cgroup.
sudo reboot
After reboot, do
sudo service docker start
You should see something like
which you won’t see if you tried to start docker service before the reboot.
6. Verify things are good
What’s next?
It’d be fun to have kubernetes running on this little device. Not sure if I should go with k3s or microk8s.