@bb2020 , is this still a draft? Are there changes you want to make?

No, this is final. I didn't have time to test it so left it as draft.

I tested on my computer. I have to admit I'm not sure if it's good enough for multi-user setup or not, but it at least solves my problem!

:/var/lib/transmission]$ ls -al
total 24
drwxrwx---  6 transmission transmission 4096 Mar  1 17:55 .
drwxr-xr-x 29 root         root         4096 Feb 23 14:25 ..
drwxrwxr-x  3 transmission transmission 4096 Feb 23 14:25 .config
drwx------  5 transmission transmission 4096 Mar  1 17:55 config
drwxrwx---  4 transmission transmission 4096 Mar  1 12:50 Downloads
drwxrwx---  2 transmission transmission 4096 Mar  1 12:50 .incomplete

I can get to my downloads now. :)

Run on the following system:

• system: "x86_64-linux"
• host os: Linux 5.4.21, NixOS, 20.03beta358.4f8bc8e10bf (Markhor)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.2
• channels(root): "nixos-20.03beta358.4f8bc8e10bf"
• channels(b): "unstable-20.03pre200231.7827d3f4497"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Great. This PR is a go then.

After switching to unstable (from 20.03) I get the following error, which I believe is caused by this change.

Jul 16 00:24:29 monster vds9x2b7c6msbm5fqwsr2w3c86xcllig-transmission-pre-start[8217]: + cp -f /nix/store/cyqf105jqpjwp1944fbghzbk4qimkr2s-settings.json /data/downloads/transmission/config/settings.json
Jul 16 00:24:29 monster vds9x2b7c6msbm5fqwsr2w3c86xcllig-transmission-pre-start[8218]: cp: cannot create regular file '/data/downloads/transmission/config/settings.json': No such file or directory
Jul 16 00:24:29 monster systemd[1]: transmission.service: Control process exited, code=exited, status=1/FAILURE
Jul 16 00:24:29 monster systemd[1]: transmission.service: Failed with result 'exit-code'.
Jul 16 00:24:29 monster systemd[1]: Failed to start Transmission BitTorrent Service.

I have services.transmission.enable = true; and services.transmission.home = "/data/downloads/transmission"; The directory /data/downloads/transmission is created with the correct permissions but is empty.

If I unset services.transmission.home everything works.

After switching to unstable (from 20.03) I get the following error, which I believe is caused by this change.

Indeed, after reverting this commit, transmission works again.

You can temporarily leave home directory as it is and set transmission.settings.download-dir like the following snippet.

services.transmission.enable = true;
services.transmission.settings = {
download-dir = "/data/downloads/transmission";
incomplete-dir-enabled = false;
};

Thanks! This works to my satisfaction.

Also disable incomplete-files to have partial files in your download directory (updated example).