In #68792 it was discovered that /dev/fuse doesn't have
wordl-read-writeable permissions anymore. The cause of this is that the
tmpfiles examples in systemd were reorganized and split into more files.
We thus lost some of the configuration we were depending on.
In this commit some of the new tmpfiles configuration that are
applicable to us are added which also makes wtmp/lastlog in the pam
module not necessary anymore.
Rationale for the new tmpfile configs:
- `journal-nowcow.conf`: Contains chattr +C for journald logs which
makes sense on copy-on-write filesystems like Btrfs. Other filesystems
shouldn't do anything funny when that flag is set.
- `static-nodes-permissions.conf`: Contains some permission overrides
for some device nodes like audio, loop, tun, fuse and kvm.
- `systemd-nspawn.conf`: Makes sure `/var/lib/machines` exists and old
snapshots are properly removed.
- `systemd-tmp.conf`: Removes systemd services related private tmp
folders and temporary coredump files.
- `var.conf`: Creates some useful directories in `/var` which we would
create anyway at some point. Also includes
`/var/log/{wtmp,btmp,lastlog}`.
Fixes#68792.
The new systemd in 19.09 gives an "Access Denied" error when doing
"systemctl daemon-reexec" on an 19.03 system. The fix is to use the
previous systemctl to signal the daemon to re-exec itself. This
ensures that users don't have to reboot when upgrading from NixOS
19.03 to 19.09.
Pretty useful for laptops. I use them with:
```
services.logind.lidSwitch = "suspend-then-hibernate";
environment.etc."systemd/sleep.conf".text = "HibernateDelaySec=8h";
```
boot.kernelPackages: check for conflicts
It's currently possible to set conflicting `boot.kernelPackages` several times.
Nixos now warns when this is the case instead of just picking one.
systemd provides two sysctl snippets, 50-coredump.conf and
50-default.conf.
These enable:
- Loose reverse path filtering
- Source route filtering
- `fq_codel` as a packet scheduler (this helps to fight bufferbloat)
This also configures the kernel to pass coredumps to `systemd-coredump`.
These sysctl snippets can be found in `/etc/sysctl.d/50-*.conf`,
and overridden via `boot.kernel.sysctl`
(which will place the parameters in `/etc/sysctl.d/60-nixos.conf`.
Let's start using these, like other distros already do for quite some
time, and remove those duplicate `boot.kernel.sysctl` options we
previously did set.
In the case of rp_filter (which systemd would set to 2 (loose)), make
our overrides to "1" more explicit.
Add support for custom device-tree files, and applying overlays to them.
This is useful for supporting non-discoverable hardware, such as sensors
attached to GPIO pins on a Raspberry Pi.
