When building an image, rather than operating on a real partition,
there's no need to have sfdisk tell the kernel to reread the partition
table. This also avoids a call to sync(2), which could be very
expensive depending on what other IO is going on on the system at the time.
Strongly inspired by the forgejo counterpart[1], for the following
reasons:
* The feature is broken with the current module and crashes on
authentication with the following stacktrace (with a PAM service
`gitea` added):
server # Stack trace of thread 1008:
server # #0 0x00007f3116917dfb __nptl_setxid (libc.so.6 + 0x8ddfb)
server # #1 0x00007f3116980ae6 setuid (libc.so.6 + 0xf6ae6)
server # #2 0x00007f30cc80f420 _unix_run_helper_binary (pam_unix.so + 0x5420)
server # #3 0x00007f30cc8108c9 _unix_verify_password (pam_unix.so + 0x68c9)
server # #4 0x00007f30cc80e1b5 pam_sm_authenticate (pam_unix.so + 0x41b5)
server # #5 0x00007f3116a84e5b _pam_dispatch (libpam.so.0 + 0x3e5b)
server # #6 0x00007f3116a846a3 pam_authenticate (libpam.so.0 + 0x36a3)
server # #7 0x00000000029b1e7a n/a (.gitea-wrapped + 0x25b1e7a)
server # #8 0x000000000047c7e4 n/a (.gitea-wrapped + 0x7c7e4)
server # ELF object binary architecture: AMD x86-64
server #
server # [ 42.420827] gitea[897]: pam_unix(gitea:auth): unix_chkpwd abnormal exit: 159
server # [ 42.423142] gitea[897]: pam_unix(gitea:auth): authentication failure; logname= uid=998 euid=998 tty= ruser= rhost= user=snenskek
It only worked after turning off multiple sandbox settings and adding
`shadow` as supplementary group to `gitea.service`.
I'm not willing to maintain additional multiple sandbox settings for
different features, especially given that it was probably not used for
quite a long time:
* There was no PR or bugreport about sandboxing issues related to
PAM.
* Ever since the module exists, it used the user `gitea`, i.e. it had
never read-access to `/etc/shadow`.
* Upstream has it disabled by default[2].
If somebody really needs it, it can still be brought back by an overlay
updating `tags` accordingly and modifying the systemd service config.
[1] 07641a91c9
[2] https://docs.gitea.com/usage/authentication#pam-pluggable-authentication-module
This adds a new `imageStream` option that can be used in conjunction
with `pkgs.dockerTools.streamLayeredImage` so that the image archive
never needs to be materialized in the `/nix/store`. This greatly
improves the disk utilization for systems that use container images
built using Nix because they only need to store image layers instead of
the full image. Additionally, when deploying the new system and only
new layers need to be built/copied.
