How to debug a conflict?


#1

I’m trying to deploy a system, and when I use nixos-18.09, I eventually get the following error:

[...]
these paths will be fetched (0.13 MiB download, 0.59 MiB unpacked):
  /nix/store/85li1z27klhsayacixqk4yhpj0q7azsc-simp_le-client-0.9.0
  /nix/store/bcab7ghpc653v0vg35qghw9dakcvdynn-python3.6-acme-0.24.0
building '/nix/store/2ands2ki7jihs6hmim1sc44c80l7sr5q-wmertens-authorized_keys.drv'...
copying path '/nix/store/bcab7ghpc653v0vg35qghw9dakcvdynn-python3.6-acme-0.24.0' from 'https://cache.nixos.org'...
building '/nix/store/g8zns8qc00df5l7lsdxrzsnz6f09qngd-system-path.drv'...
collision between `/nix/store/xy8gjkzi60fvyb5r7ky1axhawgdx1xr3-systemd-239/sbin/resolvconf' and `/nix/store/6rnjva0v7diwwn747ccbvmglib1dqgv8-openresolv-3.9.0/sbin/resolvconf'
collision between `/nix/store/xy8gjkzi60fvyb5r7ky1axhawgdx1xr3-systemd-239/bin/resolvconf' and `/nix/store/6rnjva0v7diwwn747ccbvmglib1dqgv8-openresolv-3.9.0/bin/resolvconf'
created 7737 symlinks in user environment

I don’t knowingly add anything related to resolv.conf. The same config works fine with 18.03. How to find what causes this?


#2

It’s not an error, it’s a warning. Surely it’s annoying, but I don’t think that these two particular collisions have any negative impact.


#3

I think our defaults now pull both systemd and openresolv into systemPackages. @fpletz: any idea which one should get preference? IIRC it’s possible to set that somewhere; we’d better get rid of the warning.


#4

Hmmm - the build didn’t actually switch to the new configuration though. That last line of my output is the last line of nixos-rebuild switch


#5

That’s weird. What’s the exit code? Anything interesting in systemd journal?


#6

That will be for some other reason. I’m getting the conflicts all the time. IIRC they were there at 18.09 release time.


#7

https://github.com/NixOS/nixpkgs/pull/41144 “warn differently about collisions of identical paths” might help here?


#8

These two aren’t identical. One is a script and the other one is ELF.


#9

I was experiencing the same issue in a VM with 512MB RAM. Long story short is nix-build was getting OOM killed so the last lines in the nixos-rebuild were are a bit misleading.

The nix daemon log had messages like

Jan 29 14:13:00 machine nix-daemon[960]: unexpected Nix daemon error: writing to file: Broken pipe

and the kernel log

Jan 29 16:28:49 nixos kernel: Out of memory: Kill process 11779 (nix-build) score 654 or sacrifice child
Jan 29 16:28:49 nixos kernel: Killed process 11779 (nix-build) total-vm:443200kB, anon-rss:336860kB, file-rss:0kB, shmem-rss:0kB

#10

I’ve been experiencing the same issue as well. I believe there could be two configurations trying to state the DNS server. This could be a potential issue for security, but not by much.


#11

I’ve made an issue for these warnings a while back: https://github.com/NixOS/nixpkgs/issues/55886