Please note if you are using DSM7.2 or higher you should use the Container Manager version of this guide from the menu.
This guide has reached the end of its updates as most people are now on the latest DSM update - This guide is correct as of 08/12/2023 however no further updates will be added.
Important or Recent Updates
| Historic Updates | Date |
|---|---|
| New guide released | 31/12/2021 |
| Added command to only include specific containers (thanks to TimeLord on Discord) | 01/09/2022 |
| Added notes in relation to updating GlueTUN and Torrents | 03/12/2022 |
| Added the missing ‘synobridge’ network | 16/01/2023 |
| Compose version number removed and small wording amendments | 09/04/2023 |
| Amended the path to save the compose file – this is for security, so the container has no access to the file contents. | 14/04/2023 |
| Added labels to GlueTUN container guide so updated information in this one to coincide | 06/05/2023 |
| Added a 3rd option to just exclude specific containers via a label. | 23/11/2023 |
What is Watchtower?
Watchtower is an application that watches for updates for all your containers and automatically updates them for you.
Let’s Begin
Watchtower requires access to the Docker socket, we are unable to set this up via the Synology GUI. This means we will be using Docker-Compose.
Docker Compose
We will be using Docker Compose to set up the container. In a nutshell we will be creating a text file (YAML formatted) which tells Docker exactly how we want to set up a specific container.
The next steps can be done either using a code/text editor such as Notepad++ or to keep things simple for this guide we will be using the Synology Text Editor which can be installed from the Package Center.
Open up Text Editor and click on File then New to start a new file.
We have a couple of different composes available below the first one is configured to update all running containers at 2am daily (UTC).
services:
watchtower:
image: containrrr/watchtower:latest
container_name: watchtower
environment:
- TZ=YOURTIMEZONE
- WATCHTOWER_CLEANUP=true
- WATCHTOWER_INCLUDE_STOPPED=true
- WATCHTOWER_REVIVE_STOPPED=false
- WATCHTOWER_SCHEDULE=0 0 2 * * *
volumes:
- /var/run/docker.sock:/var/run/docker.sock
restart: unless-stoppedAs an addition to the method above you can exclude specific containers from updates by adding this line to their yaml (compose) details. This is likely faster than using method 2
labels:
- com.centurylinklabs.watchtower.enable=falseThe second has an added section where you can specify the names of the containers you would like to update (use the exact name of the container as per the Synology UI)
You can copy and paste the one you wish to use into the new text file, it is important you don’t change the spacing as YAML has to be formatted correctly in order to be read by Docker Compose.
services:
watchtower:
image: containrrr/watchtower:latest
container_name: watchtower
environment:
- TZ=YOURTIMEZONE
- WATCHTOWER_CLEANUP=true
- WATCHTOWER_INCLUDE_STOPPED=true
- WATCHTOWER_REVIVE_STOPPED=false
- WATCHTOWER_SCHEDULE=0 0 2 * * *
command: # add or remove the below as required
- nzbget
- overseerr
- plex
- prowlarr
- radarr
- sonarr
- tautulli
- watchtower
volumes:
- /var/run/docker.sock:/var/run/docker.sock
restart: unless-stoppedEnvironment Variables
We need to make some changes in order for watchtower to know what time it is where you are and what we want it to do. You can amend these based on your preferences.
| Variable | Value | What it does |
|---|---|---|
| TZ | Europe/London | Change this to your own timezone |
| WATCHTOWER_CLEANUP | true or false | We want to clean up the old docker images, if you don’t turn this on over the course of a few months you will find that the images start to eat a lot of space and they are not even being used. (true or false) |
| WATCHTOWER_INCLUDE_STOPPED | true or false | Do you want to update any stopped containers, the container will stay stopped after being updated (true or false) |
| WATCHTOWER_REVIVE_STOPPED | true or false | If a stopped container is updated do you want Watchtower to start it up? (true or false) |
| WATCHTOWER_SCHEDULE | 0 0 2 * * * | Rather than setting the number of seconds to wait between checks you can set a schedule. The default I use is to check at 2am every day, you can work out your own schedule using a cron schedule generator |
Your final file should look similar to the one shown below, depending on which version you used above.
Saving the Compose File
We now need to save this file into our docker share
Click on File then Save As, navigate to the ‘docker’ share and you need to change the ‘File name’ to watchtower.yml and save it in the ‘docker’ folder.
SSH and Docker-Compose
It’s time to get logged into you Diskstation via SSH, you can do this in the same way as when you obtained your IDs in the ‘Setting up a restricted Docker user‘ guide.
Once you have logged in you will need to give 2 commands, you can copy and paste these one at a time — you will need to enter your password for the command starting with ‘sudo’
First we are going to change directory to where the watchtower.yml is located, type the below and then press enter.
cd /volume1/dockerThen we are going to instruct Docker Compose to read the file we created and complete the set-up the container. Again type the below and press enter.
sudo docker-compose -f watchtower.yml up -dWhen the command has completed you should be able to see Watchtower running in the list of containers in the Synology GUI. You can go into the container and within the log you should see that Watchtower is counting down to your next check.
You can now just leave Watchtower running you will never need to manually update your containers again.
FAQ
Q: I keep getting X container has stopped unexpectedly errors!
A: DSM does not know or understand that Watchtower is issuing commands in the background. So it makes the assumption that it was stopped unexpectedly, but we know it was Watchtower doing an update, the same happens if you issue a commands via docker-compose or even Portainer.
Q: Do I need to update Watchtower itself?
A: Nope it updates itself – quite clever really 🙂
Looking for some help, join our Discord community
If you are struggling with any steps in the guides or looking to branch out into other containers join our Discord community!
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| Historic Updates | Date |
|---|---|
| New guide released | 31/12/2021 |
| Added command to only include specific containers (thanks to TimeLord on Discord) | 01/09/2022 |
| Added notes in relation to updating GlueTUN and Torrents | 03/12/2022 |
| Added the missing ‘synobridge’ network | 16/01/2023 |
| Compose version number removed and small wording amendments | 09/04/2023 |
| Amended the path to save the compose file – this is for security, so the container has no access to the file contents. | 14/04/2023 |
Try removing redundant images with sudo docker image prune
This will remove any unused images.
Or you can do a complete cleanup with
sudo docker system prune
This will remove all unused images, stopped containers and other cached items
It’s the same…
A big thank you for all you do.
I have an error with Watchtower, and I don’t know what to do…
This is an installation with Portainer.
But I tried in SSH and same problem
Thank you for your help
level=warning msg=”Failed to retrieve container image info: Error: No such image: sha256:0d303190802119ec5897f8fa8305f7c2af47b3bd03d206f0dce83c60fe84c6e0″
I have been doing some digging and this seems like it’s a bug, if you have not done so already stop Watchtower and run this,
sudo docker-compose rm
https://stackoverflow.com/questions/37454548/docker-compose-no-such-image
Hello,
I tried everything but it still doesn’t work…
If you have an idea, I can’t thank you enough 🙂
It seems watchtower blocks vlan access when I have it setup as a container in portainer. I’m going to use it as a task to run daily to avoid this problem.
Well even got this up and running. I almost feel like a docker wizard now. Well I’d be lost without the tutorials! Keep them up. Great stuff!
Loving your guides! I have just ordered a synology NAS and will be following them and sending some coffee. Started drafting the docker compose file in preparation. I was trying to figure out how to set watchtower to only update certain containers – their seems to be an environment variable to do this, but I believe I need to set it for each container. I don’t suppose you have done this?
Hey, shout out in Discord if you have any questions when setting up. I have not done what you are after but it looks easy. You add a label of ‘com.centurylinklabs.watchtower.enable’ to you other containers in the compose file and then the Environment Variable WATCHTOWER_LABEL_ENABLE this will then only update those containers.
Bit hard to explain in the comments.
Thanks. Will give it a go, think I’ve figured out the label thing. Looks like an even simpler alternative is putting the names of the containers that I want monitored as part of the compose. Just out of interest – do you run your box with separate compose files, or a single one including all? I am unsure whether it’s critical to specify the version or not since some compose files seem to specify use of a different version at the start eg 2 vs 3
I use a single compose file in the /docker share. The version numbers don’t really make any difference to be honest at some point I used 3 and it just stuck. So there might be some slightly different numbers across the guides.
Rather than having Watchtower constantly running, I just set up a scheduled task in Synology to run it once a day and clean up after itself once it has completed. Since the container is quite small, it doesn’t have much impact and it also means you don’t need a Compose file or any command line work (although I do run Compose files through Portainer and don’t use Synology’s Docker front end at all).
docker run –rm –name watchtower \
-v /var/run/docker.sock:/var/run/docker.sock \
-e WATCHTOWER_NO_STARTUP_MESSAGE=true \
-e WATCHTOWER_RUN_ONCE=true \
-e WATCHTOWER_CLEANUP=true
There must be an error in the command.
It doesn’t run saying something is wrong but I’m not able to figure out the problem
His example has hyphens instead of double dashes in a few places. Should be “–rm –name”, not “–rm –name”.
Looks like it’s this blogging platform’s fault — did it to my examples as well :/
I will see if there is a setting I can change for the comments section, WordPress being derpy and changing