Impermanence 25.05 not populating /usr

Help
1

Hey everyone!

I’m using impermanence and I recently upgraded to NixOS version 25.05. However, I ran into a problem: my system wouldn’t boot because /usr wasn’t populated, which is usually managed by impermanence.

As a temporary workaround, I’ve set /usr to persist, but this isn’t a long-term solution. Does anyone have a proper fix for this issue?

Everything worked fine on 24.11.

Thanks in advance!

2

Definitely need more details. What errors are you getting? /usr doesn’t get populated with much (just /usr/bin/env normally; it should otherwise be empty). And it’s not impermanence that populates it, it’s just something NixOS does whenever a config is activated, which includes during boot.

2 Likes
3

Yeah my persistent /usr only has /usr/bin in it and not even /usr/bin/env:

sudo ls /usr/
bin

And this is empty altogether:

sudo ls /usr/bin

When I add it to my impermanence config like this:

  environment.persistence."/persistent" = {
    enable = true;
    hideMounts = true;
    directories = [
	...
	"/usr/"
	]

It works and without adding /usr/ it doesn’t. The error I’m getting on startup is the following:

104[!!!!!] Refusing to run in unsupported envi...ment where /usr/ is not populated.
systemd[1]: Freezing execution.
4

It sounds like something is going wrong during activation and the usrbinenv activation script isn’t working. There should be earlier messages about this. Is your rootfs not writable?

5

Thanks for your quick reply!

Unfortunately there is no error before that during bootup. My / It is a tmpfs that is mounted as rw. It is configured like this:

  fileSystems."/" =
    {
        fsType = "tmpfs";
        options = [ "defaults" "size=16G" "mode=755" ];
        neededForBoot = true;
    };

The only two other filesystems I have are /boot and /persistent which are both written to disk.

I didn’t change anything in my config and only upgraded from 24.11 to 25.05 so that is the most likely culprit.

6

Note that failures in the activation script may not cause the bootup process to stop and might just log the messages.

At this point I think I just need to see the rest of your config. I’m also trying to think of a good way to get into a shell to do things like checking dmesg. Like you could put init=/nix/var/nix/profiles/system/sw/bin/bash in the kernel params (replacing the init= that’s there by default) and then run activation manually and look through dmesg.

2 Likes
7

Found the issue. Thanks for your help! It was envfs. If I enable envfs I have problems booting and without everything works.

services.envfs.enable = true;

Can someone check if their system works with both envfs and impermanence enabled on 25.05?