Docker on ARM-based Synology DS-line devices
This article guides you how to configure Docker on Synology’s cheapest line of devices like DS220J or DS218 w lack of official support for Docker from the Synology side.
Initially I’ve described how to configure the Docker on DS220J but basing on readers’ reports I can say it also works for 64bit CPUs on DS218.
Important: Keep in mind if you are using your synology as NAS and wants to setup docker for HomeAssistant it may consume too much Synology’s resources and may lead to performance issues related to hardware - I have finally separated my Synology and HomeAssistant by installing HA on Raspberry PI - but you may have different use case than mine and this guide may be helpful for you :)
The problem
I love Docker, it makes my work simpler and helps me to keep the environment of my OS clean. I can play with software without the risk of the damaging impact (hard to revert/control some modifications) of the introduced changes.
ARM platform became more and more popular in the IoT world, the good thing is our NAS is based on ARM CPU.
The Synology server is the best fit for HomeAssistant if you have Synology already and thinking to play with smart home solutions but when you try to configure your NAS as a HomeAssistant you end up with nothing or spend hours trying to make it work.
In my case I was disappointed the HomeAssistant package is available on package center only for more expensive Synology and started thinking to obtain RaspberryPI but it is another device in my home which consumes energy just for running HomeAssistant while Synology is working as a file server it caused me to try again, and I managed it :)
It only applies to the Synology products which are running on ARM-based 32bit processors
You have few options here:
- Try to install HomeAssistant from sources
- Forget about Synology as a runtime environment for Docker
- or do what I did when I’ve decided to dig deeper and understand the Synology architecture
What we need
- SSH access enabled on Synology -> (Go to DSM UC > Control Panel > Terminal & SNMP > Terminal, and tick Enable SSH service)
- Static binaries of docker | Binaries List
- Knowledge of how to integrate it with our OS
Don’t worry I’ll explain to you step by step how to make it working on your ARM-32bits-based server.
Let’s start
Overview, gathering facts
Please SSH-in to your Synology. If you are using OS X or Linux open up the terminal and type.
ssh admin@YOURIP
Windows users need to use the PUTTY client.
Synology file structure
Synology is running on build-in volume which is relatively small ~2.3G You need to know all of your docker images which you download from internet needs to be stored somewhere else. So where? In your data volume, so for the purpose of this guide I’ll name it as volume1, and we are assuming it is placed here
/volume1
Call df -h to list your volumes
admin@KFC:~$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/md0 2.3G 1.7G 520M 77% /
none 249M 0 249M 0% /dev
/tmp 250M 944K 250M 1% /tmp
/run 250M 2.7M 248M 2% /run
/dev/shm 250M 4.0K 250M 1% /dev/shm
none 4.0K 0 4.0K 0% /sys/fs/cgroup
/dev/vg1000/lv 913G 636G 277G 70% /volume1
So mine is the last one on the list, and I’d use it for the Docker images persistence.
CPU info
My Synology DS220 sudo cat /proc/cpuinfo output:
admin@KFC:~# cat /proc/cpuinfo
processor : 0
model name : ARMv7 Processor rev 1 (v7l)
BogoMIPS : 2655.84
Features : swp half thumb fastmult vfp edsp neon vfpv3 tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x4
CPU part : 0xc09
CPU revision : 1
processor : 1
model name : ARMv7 Processor rev 1 (v7l)
BogoMIPS : 2655.84
Features : swp half thumb fastmult vfp edsp neon vfpv3 tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x4
CPU part : 0xc09
CPU revision : 1
Hardware : Marvell Armada 380/381/382/383/384/385/388 (Device Tree)
Revision : 0000
Serial : 0000000000000000
Ok, so what does it mean to me, if the Docker static list shows the list something like that:
aarch64/
armel/
armhf/
ppc64le/
s390x/
x86_64/
Useful explanation you can find here:
- The ARM EABI (armel) port targets a range of older 32-bit ARM devices, particularly those used in NAS hardware and a variety of *plug computers.
- The newer ARM hard-float (armhf) port supports newer, more powerful 32-bit devices using version 7 of the ARM architecture specification.
- The 64-bit ARM (arm64) port supports the latest 64-bit ARM-powered devices.
Source: https://www.debian.org/ports/arm/index.en.html
So ours is armhf
Binaries download & testing
Ok, we know a little more about or hardware, so it is a good time to download binaries and proceed with the installation.
Go to your home directory and prepare a directory for the download and extraction of the archive
cd ~/
mkdir docker_install
cd docker_install
wget URL_TO_DOCKER_BINARY_GOES_HERE
You need to replace phrase: URL_TO_DOCKER_BINARY_GOES_HERE with valid URL to the most recent docker binary for example docker-19.03.9 taken from here
Ok, let’s extract the repository
tar xvf docker-x.x.x.tgz
Where docker-x.x.x.tgz is downloaded TAR archive
Before we install the extracted files we can test is the docker binary compatible with our OS, so let’s change the directory to extracted one and test the binary like below:
cd docker
./docker --version
the output example:
Docker version 19.03.8, build afacb8b
The output should be the downloaded docker version info of the docker binary if we receive an error message instead it means we downloaded an incompatible package.
IMPORTANT: I’ve got segmentation fault error for next releases higher than 19.03.8 so if you are getting this error to 19.03.8 should work for you.
Docker installation
You can go to this document directly or read the entire description below
Let’s check where you are
pwd
should output
/admin/docker-install/docker
Time to install your docker:
- IMPORTANT you are in the extracted directory of docker archive
- What we are going to do right now
- Change directory to level up just for safety and readability
- Copy all binaries to
/usr/bin/directory - Cleanup downloaded resources
cd /admin/docker-install
sudo cp docker/* /usr/bin/
Start the Docker daemon:
sudo dockerd
If no error message is thrown means it runs :)
Press CTRL+C to stop the running process.
Additional configuration
We need to tell Docker we need to store data in our /volume1 but before we need to create a place for Docker there
mkdir /volume1/docker
Docker needs a config file for that:
so you need to create/edit following file /etc/docker/daemon.json
{
"storage-driver": "vfs",
"iptables": false,
"bridge": "none",
"data-root": "/volume1/docker"
}
Configuration testing
To test docker can run call dockerd command
dockerd
To stop press CTRL+C
Reboot your Synology you can type
sudo reboot
Once it is up SSH-in again and type to test your Docker
sudo docker run hello-world
You should see finally the output from the hello-world container
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(arm32v5)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
CONGRATULATIONS YOU HAVE SUCCESSFULLY INSTALLED DOCKER ON your ARM-32b-based NAS!