NixOS
fetchGit is flaky: sometimes cannot find git revision
Describe the bug
The problem only occurs since nix 2.21.x
fetchGit is flaky on an empty ~/.cache/nix/gitv3 and can often crash like that:
error: Cannot find Git revision '43c751b41d74f96cbbd4e07b7aec9675651e2951' in [...]
Steps To Reproduce
- Evaluate
fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951";}on an empty~/.cache/nix/gitv3several times in a row. - notice that sometimes the fetching works and sometimes it crashes.
- To speed up the evaluation, you can set
shallow=true. It does not affect the outcome.
Here an example with 3 evaluations of the same expression, succeeding 2 times and failing one time.
❯ rm -rf ~/.cache/nix/gitv3
~
❯ nix repl
Nix 2.21.2
Type :? for help.
nix-repl> fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }
fatal: unable to access 'https://github.com/sebastianbergmann/environment.git/': Could not resolve host: github.com
warning: could not read HEAD ref from repo at 'https://github.com/sebastianbergmann/environment.git', using 'master'
warning: could not update mtime for file '/home/grmpf/.cache/nix/gitv3/0da421j037zz3w3qxl31dc3r7s84xsrgr7hs25yn3ic0h6iqald1/refs/heads/master': No such file or directory
fatal: Refusing to point HEAD outside of refs/
warning: could not update cached head 'master' for 'https://github.com/sebastianbergmann/environment.git'
{
lastModified = 1681191566;
lastModifiedDate = "20230411053926";
narHash = "sha256-Ttez88NVbtHeT/4AglFTEdsGqLgkKTuvqP7uR4tP7BI=";
outPath = "/nix/store/391g2lyf8f1014riqpfdbn93s9gjv42h-source";
rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951";
revCount = 448;
shortRev = "43c751b";
submodules = false;
}
~ took 13s
❯ rm -rf ~/.cache/nix/gitv3
~
❯ nix repl
Nix 2.21.2
Type :? for help.
nix-repl> fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }
warning: could not update mtime for file '/home/grmpf/.cache/nix/gitv3/0da421j037zz3w3qxl31dc3r7s84xsrgr7hs25yn3ic0h6iqald1/refs/heads/main': No such file or directory
{
lastModified = 1681191566;
lastModifiedDate = "20230411053926";
narHash = "sha256-Ttez88NVbtHeT/4AglFTEdsGqLgkKTuvqP7uR4tP7BI=";
outPath = "/nix/store/391g2lyf8f1014riqpfdbn93s9gjv42h-source";
rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951";
revCount = 448;
shortRev = "43c751b";
submodules = false;
}
~ took 49s
❯ rm -rf ~/.cache/nix/gitv3
~
❯ nix repl
Nix 2.21.2
Type :? for help.
nix-repl> fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }
fatal: unable to access 'https://github.com/sebastianbergmann/environment.git/': Could not resolve host: github.com
warning: could not update mtime for file '/home/grmpf/.cache/nix/gitv3/0da421j037zz3w3qxl31dc3r7s84xsrgr7hs25yn3ic0h6iqald1/refs/heads/main': No such file or directory
error:
… while calling the 'fetchGit' builtin
at «string»:1:1:
1| fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }
| ^
… while fetching the input 'git+https://github.com/sebastianbergmann/environment.git?exportIgnore=1&rev=43c751b41d74f96cbbd4e07b7aec9675651e2951'
error: Cannot find Git revision '43c751b41d74f96cbbd4e07b7aec9675651e2951' in ref 'refs/heads/main' of repository 'https://github.com/sebastianbergmann/environment.git'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.
What can be observed is that the warnings raised by nix are not reproducible as well. Though, I could not determine any correlation between the warnings and the outcome.
Expected behavior
nix-env --version output
Additional context
Add any other context about the problem here.
Priorities
Add :+1: to issues you find important.
Small correction. I mistakenly associated the buildbot eval failure of https://github.com/nix-community/dream2nix/pull/921 with the current bug, but in fact the reason for it was a missing allRefs = true which made pre 2.20 nix versions fail.
Nevertheless the current bug still exists and I had to downgrade my nix version to 2.20.x to be able to do my work.
This problem appears no longer in the latest nix version:
% nix-shell -p nixVersions.nix_2_24
[nix-shell:~]$ nix repl
Nix 2.24.3
Type :? for help.
nix-repl> fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }
warning: could not update mtime for file '/home/joerg/.cache/nix/gitv3/0da421j037zz3w3qxl31dc3r7s84xsrgr7hs25yn3ic0h6iqald1/refs/heads/main': error: changing modification time of '"/home/joerg/.cache/nix/gitv3/0da421j037zz3w3qxl31dc3r7s84xsrgr7hs25yn3ic0h6iqald1/refs/heads/main"': No such file or directory
{
lastModified = 1681191566;
lastModifiedDate = "20230411053926";
narHash = "sha256-Ttez88NVbtHeT/4AglFTEdsGqLgkKTuvqP7uR4tP7BI=";
outPath = "/nix/store/391g2lyf8f1014riqpfdbn93s9gjv42h-source";
rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951";
revCount = 448;
shortRev = "43c751b";
submodules = false;
}
I don't remember exactly where, but I remember there were some changes done to not using libgit or something.
I am also testing this loop now, but so far no failures:
set -eux
for _ in $(seq 1 1000); do
rm -rf ~/.cache/nix/gitv3
nix eval --expr 'fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }'
done
I believe the fix for #11012 might have fixed this as well? However GitHub does support shallow and it was specified shallow did not affect the outcome, so not 100% convinced.
Anyways, good thing it is fixed.
I'm encountering this when trying to fetch some old commits on a poor connection such as
error:
… while calling the 'fetchGit' builtin
at «string»:1:1:
1| builtins.fetchGit {url = "https://github.com/KhronosGroup/Vulkan-Hpp.git"; shallow=true; rev = "128261aa4517aaf3b30809a27311dd7e1cb5dbea"; allRefs=true;}
| ^
… while fetching the input 'git+https://github.com/KhronosGroup/Vulkan-Hpp.git?exportIgnore=1&rev=128261aa4517aaf3b30809a27311dd7e1cb5dbea&shallow=1'
error: Cannot find Git revision '128261aa4517aaf3b30809a27311dd7e1cb5dbea' in ref 'refs/heads/main' of repository 'https://github.com/KhronosGroup/Vulkan-Hpp.git'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.
I've been encountering this as well. I host a Git server (Forgejo) where I host my OS/ZSH/NeoVim configs and I encounter this pretty often. Most of the time it works again after nix flake update. So far I haven't figured out when/why this happens but it always appears after a while when I don't check for updates on these inputs.
EDIT: Well today it didn't help. Had to append .git to the URL so that it triggers a rewrite of those inputs in the lock file.
In my case only root user is facing the issue. Any idea why?
# rm -fr ~/.cache/nix/gitv3/
# nix repl
Nix 2.24.12
Type :? for help.
nix-repl> builtins.fetchGit { url = "https://github.com/intel/ipu6-drivers.git"; ref = "master"; rev = "b4ba63df5922150ec14ef7f202b3589896e0301a"; }
error: executing 'git': No such file or directory
error:
… while calling the 'fetchGit' builtin
at «string»:1:1:
1| builtins.fetchGit { url = "https://github.com/intel/ipu6-drivers.git"; ref = "master"; rev = "b4ba63df5922150ec14ef7f202b3589896e0301a"; }
| ^
… while fetching the input 'git+https://github.com/intel/ipu6-drivers.git?exportIgnore=1&ref=master&rev=b4ba63df5922150ec14ef7f202b3589896e0301a'
error: Cannot find Git revision 'b4ba63df5922150ec14ef7f202b3589896e0301a' in ref 'master' of repository 'https://github.com/intel/ipu6-drivers.git'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.
$ nix repl
Nix 2.24.12
Type :? for help.
nix-repl> builtins.fetchGit { url = "https://github.com/intel/ipu6-drivers.git"; ref = "master"; rev = "b4ba63df5922150ec14ef7f202b3589896e0301a"; }
{
lastModified = 1739777904;
lastModifiedDate = "20250217073824";
narHash = "sha256-CmIRiz+xCBArl6shFW0vzegYsMUdaeons4r9ycNEvPg=";
outPath = "/nix/store/xjn9dlr45zr4i7vckinp79gh3kz6k138-source";
rev = "b4ba63df5922150ec14ef7f202b3589896e0301a";
revCount = 220;
shortRev = "b4ba63d";
submodules = false;
}
Repeatedly hitting this on a low-power device with a relatively slow connection (pi). Same config working fine on other devices. Had hoped that a nix-prefetch-url would resolve it, but alas -- it succeeds but nixos-rebuild fails.
I had a similar issue that led me here — I was trying to build https://github.com/akarbas/configs, and was getting the following error:
% make
cd darwin && nix build .#darwinConfigurations.UNiCORN.system \
--extra-experimental-features 'nix-command flakes'
warning: Git tree '/Users/amin/dev/personal/configs' is dirty
evaluation warning: `programs.zsh.initExtra` is deprecated, use `programs.zsh.initContent` instead.
Example: programs.zsh.initContent = "your content here";
cd darwin && sudo ./result/sw/bin/darwin-rebuild switch --flake .#UNiCORN
building the system configuration...
warning: Git tree '/Users/amin/dev/personal/configs' is dirty
fatal: unable to access 'https://github.com/flox/httpmock.git/': SSL certificate problem: unable to get local issuer certificate
error:
… while calling the 'derivationStrict' builtin
at <nix/derivation-internal.nix>:37:12:
36|
37| strict = derivationStrict drvAttrs;
| ^
38|
… while evaluating derivation 'darwin-system-25.05.75b99da'
whose name attribute is located at /nix/store/baqymak7x7mr5y719pyflz7fcm9rmkxb-source/pkgs/stdenv/generic/make-derivation.nix:480:13
… while evaluating attribute 'activationScript' of derivation 'darwin-system-25.05.75b99da'
at /nix/store/58l69qyjjrxvacf943jinrdb6c7mb12p-source/modules/system/default.nix:97:7:
96|
97| activationScript = cfg.activationScripts.script.text;
| ^
98|
… while evaluating the option `system.activationScripts.script.text':
… while evaluating definitions from `/nix/store/58l69qyjjrxvacf943jinrdb6c7mb12p-source/modules/system/activation-scripts.nix':
… while evaluating the option `system.activationScripts.applications.text':
… while evaluating definitions from `/nix/store/58l69qyjjrxvacf943jinrdb6c7mb12p-source/modules/system/applications.nix':
(stack trace truncated; use '--show-trace' to show the full, detailed trace)
error: Cannot find Git revision '84956ea0e3ab4cc44919e4a06862644b58c09469' in ref 'refs/heads/flox/remove_recording_struct' of repository 'https://github.com/flox/httpmock.git'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.
make: *** [Makefile:17: darwin] Error 1
I verified in nix repl that I can fetch that git repo/revision. The solution was running this command once:
cd nix/darwin && sudo -E ./result/sw/bin/darwin-rebuild switch --flake .#UNiCORN --option sandbox false
Specifically, --option sandbox false. Now it works w/o the flag.
HTH!
I was having similar issues and the real problem was that the user didn't have access to the git repo. Granting them access solved the issue. IMHO the message should be clearer. Something like "Cannot find Git repo" would help more than "Cannot find Git revision" in this case.
Commenting here in case it helps someone else.
Isn't the problem:
fatal: unable to access 'https://github.com/sebastianbergmann/environment.git/': Could not resolve host: github.com
Wouldn't that mean that the git repo wasn't even fetched? Then of course the commit isn't found in the repo... nothing was fetched.
I think this is poor network but the error at the bottom is not making that clear
# create a network namespace
sudo ip netns add no-dns
# enter network namespace
sudo ip netns add no-dns
nix eval --expr 'fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }'
warning: you don't have Internet access; disabling some network-dependent features
fatal: unable to access 'https://github.com/sebastianbergmann/environment.git/': Failed to connect to github.com port 443 after 30 ms: Could not connect to server
warning: could not read HEAD ref from repo at 'https://github.com/sebastianbergmann/environment.git', using 'master'
fatal: unable to access 'https://github.com/sebastianbergmann/environment.git/': Failed to connect to github.com port 443 after 4 ms: Could not connect to server
fatal: Refusing to point HEAD outside of refs/
warning: could not update cached head 'master' for 'https://github.com/sebastianbergmann/environment.git'
error:
… while calling the 'fetchGit' builtin
at «string»:1:1:
1| fetchGit { url="https://github.com/sebastianbergmann/environment.git"; rev = "43c751b41d74f96cbbd4e07b7aec9675651e2951"; }
| ^
… while fetching the input 'git+https://github.com/sebastianbergmann/environment.git?exportIgnore=1&rev=43c751b41d74f96cbbd4e07b7aec9675651e2951'
error: Cannot find Git revision '43c751b41d74f96cbbd4e07b7aec9675651e2951' in ref 'master' of repository 'https://github.com/sebastianbergmann/environment.git'! Please make sure that the rev exists on the ref you've specified or add allRefs = true; to fetchGit.
It looks like it's "flaky" but the repo really was never cloned.
https://github.com/NixOS/nix/pull/13449 should help and make it more clear.