Pi-hole in Docker on a Synology NAS

Last updated on 27 October 2023

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.

Update	Date
Updated the environment variables from ‘FTLCONF_REPLY_ADDR4’ to ‘FTLCONF_LOCAL_IPV4’	10/10/2022

What is Pi-hole?

If you are looking to get advertising and tracking blocked across all the devices on your network a Pi-hole will have you covered. It’s a locally hosted Domain Name Server and uses block lists to stop adverts.

Let’s Begin

Couple of things to note and common questions:

• Pi-hole is not able to block YouTube ads
• You will need to change the DNS settings either on your Router or whatever device is managing your DHCP/DNS settings
• You will not be able to use this in conjunction with the DHCP server built into DSM if you have that enabled you will need to turn it off before continuing.

In order for you to successfully use this guide please complete these two steps first.

• Step 2: Setting up a restricted Docker user

Downloading the Pi-hole Image

Open up Docker within DSM and navigate to the ‘Registry’ section and search for ‘pihole’ in the search box. Download the official version.

The pop-up box will ask which version you want to download, make sure you choose ‘Latest’ from the list of available versions.

You can check the status of the download over on the ‘Image’ tab.

Setting up the container

In Docker click on the ‘Image’ tab, in the list of your containers select the ‘PiHole’ image and click on ‘Launch’

The first screen will ask how you want to set up the Docker network, to keep things simple we will be using the Docker Host option which means we will not need to set up any additional ports. Click Next once you have selected the option.

General Settings

Next you will be greeted with the General Settings screen, this is where you can start specifying some of your preferences.

You can change the name of the container to anything you like, and you may want to enable Auto Restart as this will ensure Pi-hole starts automatically if you reboot your NAS.

You will also notice a Configure capabilities button — don’t change anything in here!

Keep in mind if you turn off your Diskstation or stop the container you will lose internet access as there will be no way for devices to resolve DNS queries.

Next up we are going to click on the ‘Advanced Settings’ button, this will take you to a new window with a number of tabs which we are going to work through.

Environment

Next we are going to set up a some environment variables that docker will use to allow the container to access our local file system by telling it the IDs to use for file permissions

For each of the items in the table below you will need to click on ‘Add’ button then type each of the below in the ‘variable’ and ‘value’ sections.

Variable	Value
PIHOLE_UID	The UID you obtained in the user setup guide
PIHOLE_GID	The GID you obtained in the user setup guide
WEB_UID	The UID you obtained in the user setup guide
WEB_GID	The GID you obtained in the user setup guide
TZ	Your timezone wikipedia.org/wiki/List_of_tz_database_time_zones
WEBPASSWORD	A password of your choice for the Pi-hole web interface
DNSMASQ_USER	pihole
DNSMASQ_LISTENING	local
WEB_PORT	8000

Once you have entered the above scroll down the Environment Variables and you will be able to see one called FTLCONF_LOCAL_IPV4 you need to enter the IP address of your NAS.

Variable	Value
FTLCONF_LOCAL_IPV4	Enter the IP of you NAS

Links / Execution Command

You do not need to set up anything on these tabs.

Press ‘Save’ to go back to the initial setup screen, then press ‘Next’

Volume Settings

We will now be specifying the directories where Pi-hole will store its configuration files.

We first click on ‘Add folder’ so we can create some folders for the config files to live, first create one called ‘pihole’ inside your /docker share.

Then within that folder create two new folders called ‘dnsmasq.d’ and ‘pihole’

You will now add each of these folders in line with the table / screenshot below

File/Folder	Mount Path
/docker/pihole/dnsmasq.d	/etc/dnsmasq.d
/docker/pihole/pihole	/etc/pihole

Click Next to move to the final screen.

Summary

You have now completed the container setup.

You will be shown an overall summary of the settings we have specified, this is a good time to double-check everything is correct. Finally, click on Done and the container should start to boot.

After about 30 seconds or so you should then be able to access the Pi-hole web interface via you NAS IP followed by port 8000, and log in with the password you set earlier.

e.g. 192.168.0.46:8000

You will now need to add the IP address of your NAS as your DNS address in your router or other DHCP server. It can take some time for all of your devices to move over the new DNS settings so be patient, and you will gradually start to see your stats begin to start.

Also note as we are not using Pi-hole as the DHCP server you will not be able to see the names of the devices in the statistics just their IP addresses.

That’s it!

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Historic Updates	Date
New guide released	20/09/2021
Fixed a typo in the Environment Variables and added note around DHCP	25/11/2021
Additional environment variable added to fix a start-up error due to changes in the 2022.01 release and onward of PiHole.	14/01/2022
Environment Variables updated to the latest requirements – Now runs as your locally created docker user rather than root	07/04/2022
Updated screenshots and steps for DSM7.1	11/06/2022
Restored the guide to 11/06 network setup due to an error on my part and updated environment variables	22/08/2022

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