TIL: How to run Docker in rootless mode

Feb 4, 2025. 228 words. 2 minutes. In TIL. Docker System Linux

For a long time I thought that it was best practice to run Docker in root mode, i.e., running all commands with sudo. As this can get annoying very quickly (as is so often the case with security practices…), I read a lot of guides how to circumvent this, often involving insecure practices like messing with the sudo group. So in the name of (perceived?) security, I never bothered much with it and just typed my sudo in front of every command.

As I was collaborating on a shared project with a colleague, the issue arose again, as he had a setup without the need for calling Docker with sudo. So I researched the topic again and there is actually an official guide from Docker for this with a clean solution ¹. It boils down to these two lines:

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# Install some required tools.
sudo apt install -y uidmap

# Run the official tool to setup rootless mode.
dockerd-rootless-setuptool.sh install

Afterwards, any image needs to be rebuilt and each container needs to be restarted, as the rootless Docker runs in its own domain, so sudo docker ps and docker ps actually would return different results.

There are some caveats and limitations that the documentation describes, but nothing that affects me (so far). Your mileage may vary!

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