Raspberry Pi 4 with Docker
I use Raspberry Pi 4s to host services for my home network, with Docker to keep things manageable in containers. Each Pi has a USB SSD as its boot drive running Raspberry Pi OS.
There's often a bit of boilerplate I need to keep track of to set up a new one, so I am documenting all of the snippets here for my future self.
- Increase Swap Size
- Disable DHCP for Virtual Ethernet Interfaces
- Install Docker
- Disable nftables
- Make SSH Secure
- Managing Docker Compose
- Passwordless Sudo
- Temperature and Speed
- Architecture Emulation
Increase Swap Size
If you're using an SSD as a boot drive, the default 100MB limit for Swap doesn't make sense. There is a great article here documenting how to change this, but the key bits are:
sudo nano /etc/dphys-swapfile
CONF_SWAPSIZE, since it is explicitly set to 100. Commenting it out makes the OS manage it automatically, and in my case made the swap size 2GB.
Then restart the Swap service:
sudo /etc/init.d/dphys-swapfile restart
You can use
free -m or
htop to verify the change.
Disable DHCP for Virtual Ethernet Interfaces
Docker creates a lot of virtual ethernet interfaces, and they all start requesting IP addresses and it all ends very badly (the Pi will drop off the network at some point after being on for a while).
The fix is to tweak the DHCP config:
sudo nano /etc/dhcpcd.conf
Add the following to the very top of the file:
Then restart the DCHP daemon:
sudo systemctl daemon-reload sudo systemctl restart dhcpcd
The best thing to do to set up Docker for the first time is the following:
sudo apt-get update sudo apt-get upgrade sudo reboot
The reboot at the end is crucial, as I found some Docker installation errors when not rebooting.
curl -fsSL https://get.docker.com -o get-docker.sh sudo sh get-docker.sh sudo reboot
That last reboot is just for good measure - it's probably not necessary. Then you're good to go!
I ran into an issue where Raspberry Pi OS installed an update which bricked the Docker daemon, because the update forced a switch from
nftables (Docker wanted
iptables). I ended up fixing it by forcing the use of
iptables, then re-installing docker.
sudo update-alternatives --set iptables /usr/sbin/iptables-legacy sudo update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy sudo update-alternatives --set arptables /usr/sbin/arptables-legacy sudo update-alternatives --set ebtables /usr/sbin/ebtables-legacy
Make SSH Secure
To make SSH more secure, we should disable username/password auth.
sudo nano /etc/ssh/sshd_config
Comment out every entry, so the file only has the following uncommented entries (you could delete the file contents and replace it with the below, but then you lose all of the documentation):
Include /etc/ssh/sshd_config.d/*.conf PermitRootLogin no PasswordAuthentication no PermitEmptyPasswords no ChallengeResponseAuthentication no UsePAM no X11Forwarding yes PrintMotd no AcceptEnv LANG LC_* Subsystem sftp /usr/lib/openssh/sftp-server
Then restart SSH:
sudo systemctl restart ssh
Managing Docker Compose
To deploy a service with Docker Compose, go to the directory containing the
docker-compose.yml file, then:
sudo docker compose up -d
To update a Docker compose service:
sudo docker compose pull
To remove the service:
sudo docker compose down
To enable passwordless sudo:
sudo visudo /etc/sudoers.d/010_pi-nopasswd
Then change the content to:
pi ALL=(ALL) ALL
pi is the username you're logging in with.
If you have adequate active cooling set up around your Pi, you can go for glory with the CPU clock speed:
sudo nano /boot/config.txt
#uncomment to overclock the arm. 700 MHz is the default. over_voltage=6 arm_freq=2147
This clocks the CPU up to 2.1GHz.
Temperature and Speed
Measure the current CPU frequency in Hz:
vcgencmd measure_clock arm frequency(48)=1800457088
Get the CPU temperature:
vcgencmd measure_temp temp=59.4'C
Get the CPU temperature, but update live:
watch --interval 0.1 -- 'vcgencmd measure_temp'
If you need to run non-ARM Docker containers, you can install an emulation layer. This article has an in-depth explanation: Run AMD64 Docker Images On An ARM Computer
The below command enables
amd64 support via the following library: https://github.com/tonistiigi/binfmt
sudo docker run --privileged --rm tonistiigi/binfmt --install amd64
AMD64 containers will now run, just much more slowly than on the native hardware.
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