I started to wonder quite recently why Hydra doesn't send email
notifications anymore to me. I saw the following issue in the log of
`hydra-notify.service`:
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1887289]: fatal: unsafe repository ('/var/lib/hydra/scm/git/3e70c16c266ef70dc4198705a688acccf71e932878f178277c9ac47d133cc663' is owned by someone else)
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1887289]: To add an exception for this directory, call:
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1887289]: git config --global --add safe.directory /var/lib/hydra/scm/git/3e70c16c266ef70dc4198705a688acccf71e932878f178277c9ac47d133cc663
May 22 11:57:29 hydra 9bik0bxyxbrklhx6lqwifd6af8kj84va-hydra-notify[1886654]: error running build_finished hooks: command `git log --pretty=format:%H%x09%an%x09%ae%x09%at b0c30a7557685d25a8ab3f34fdb775e66db0bc4c..eaf28389fcebc2beca13a802f79b2cca6e9ca309 --git-dir=.git' failed with e>
This is also a problem because of Git's fix for CVE-2022-24765[1], so I
applied the same fix as for Nix[2], by using `--git-dir` which skips the
code-path for the ownership-check[3].
[1] https://lore.kernel.org/git/xmqqv8veb5i6.fsf@gitster.g/
[2] https://github.com/NixOS/nix/pull/6440
[3] To quote `git(1)`:
> Specifying the location of the ".git" directory using this option
> (or GIT_DIR environment variable) turns off the repository
> discovery that tries to find a directory with ".git" subdirectory
This in-progress feature will run a dynamically generated set of
buildFinished hooks, which must be nested under the `runCommandHook.*`
attribute set. This implementation is not very good, with some to-dos:
1. Only run if the build succeeded
2. Verify the output is named $out and that it is an executable file
(or a symlink to a file)
3. Require the jobset itself have a flag enabling the feature, since
this feature can be a bit dangerous if various people of different
trust levels can create the jobs.
Using a sha1 of the command combined with the build ID is not a
particularly good or unique identifier:
* A build could fail, be restarted, and then succeed -- assuming no
configuration changes, the sha1 hash of the command as well as the build
ID will be the same. This would lead to an overwritten log file.
* Allowing user input to influence filenames is not the best of ideas.
Since breaking the filename construction out to a helper function,
Hydra::Model::DB is no longer used. Importing Hydra::Helper::Nix,
however, has the potential to break tests, so just use the functions we
need without importing the entire module.
run3 just seems to do better handling for what we want to do, and
requires less deep-reaching changes to this plugin to get it to play
nice, as IPC::Run::run would.
This uses the somewhat restrictive umask of 0027 so that people outside
the user or group cannot read the files. This also helps to inhibit
TOCTOU where someone else has a handle to our file before we chmod it
and after we close it.
