Docker service exists even though it supposedly shouldn't

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1

The command systemctl status docker shows

× docker.service - Docker Application Container Engine
     Loaded: loaded (/etc/systemd/system/docker.service; enabled; preset: enabled)
    Drop-In: /nix/store/gfh802s9scwvs8r7xg5haxhqq2p8ggl0-system-units/docker.service.d
             └─overrides.conf
     Active: failed (Result: exit-code) since Tue 2023-11-28 07:56:27 +07; 5h 10min ago
TriggeredBy: × docker.socket
       Docs: https://docs.docker.com
    Process: 3213 ExecStart=/nix/store/p9ji44qs3ka8k2zxpn542q5pfz3vfnzv-docker-24.0.5/bin/dockerd --config-file=/nix/store/2mz7fdnkfi6z8rapwawj1fgla16wax81-daemon.json (code=exited, status=1/FAILURE)
   Main PID: 3213 (code=exited, status=1/FAILURE)
         IP: 0B in, 0B out
        CPU: 187ms

Nov 28 07:56:27 mightyiam-desktop systemd[1]: docker.service: Scheduled restart job, restart counter is at 3.
Nov 28 07:56:27 mightyiam-desktop systemd[1]: docker.service: Start request repeated too quickly.
Nov 28 07:56:27 mightyiam-desktop systemd[1]: docker.service: Failed with result 'exit-code'.
Nov 28 07:56:27 mightyiam-desktop systemd[1]: Failed to start Docker Application Container Engine.

My system configuration, as far as I can tell, has currently no docker enabled. I certainly don’t have virtualization.docker.enable mentioned in my source files… I did have that enabled in the past. So, question is, how do I find out what this service is doing in my system, please?

2

There might be a better way. But I’ve been doing this:

$ cd /path/to/nixpkgs/nixos/modules/
$ rg virtualisation.docker.enable
# check if any module in the output is used
3

Ideally, I would ask the store questions such as “what gc roots is this docker store path a part of?”. I don’t know how to do that yet.

4 
nix-store --query --roots `which docker`

/nix/var/nix/profiles/system-480-link -> /nix/store/36970gazm3dm0wmxb50q3rg36i1cjhgv-nixos-system-mightyiam-desktop-24.05pre553283.8cfef6986adf
/nix/var/nix/profiles/system-477-link -> /nix/store/995k9nbdpms5san8f2drxf3gqw9p5xid-nixos-system-mightyiam-desktop-24.05pre552293.5a09cb4b393d
/proc/16371/maps -> /nix/store/zr27y09axp3xyn7r0v8kid4ff4h0gk9c-system-path
/proc/16201/maps -> /nix/store/zr27y09axp3xyn7r0v8kid4ff4h0gk9c-system-path
/nix/var/nix/profiles/system-478-link -> /nix/store/cidv90dhcz5fja459k8j1w0sr8y9cm2f-nixos-system-mightyiam-desktop-24.05pre552293.5a09cb4b393d
/nix/var/nix/profiles/system-481-link -> /nix/store/d5a2bssfvg55zl6z04kg47h15x78giqf-nixos-system-mightyiam-desktop-24.05pre553283.8cfef6986adf
/run/current-system -> /nix/store/d5a2bssfvg55zl6z04kg47h15x78giqf-nixos-system-mightyiam-desktop-24.05pre553283.8cfef6986adf
/nix/var/nix/profiles/system-476-link -> /nix/store/acnkvrxgdhc001vdf11sdxfdwdnbjv2x-nixos-system-mightyiam-desktop-24.05beta357.19cbff58383a
/run/booted-system -> /nix/store/yksmid03rahmpxkbpnl39441n60glrky-nixos-system-mightyiam-desktop-24.05pre552293.5a09cb4b393d
/nix/var/nix/profiles/system-479-link -> /nix/store/yksmid03rahmpxkbpnl39441n60glrky-nixos-system-mightyiam-desktop-24.05pre552293.5a09cb4b393d

The first line is the current system:

nixos-version

24.05pre553283.8cfef6986adf (Uakari)

Which I find somewhat concerning, because I don’t seem to have virtualization.docker.enable… oh, wait. I do. There’s a part of my configuration that is not checked in. It’s system-specific and brief, so that’s why it’s not checked in. And I didn’t consider virtualisation.docker.enable = true; might be set there. And it was.