This makes it easier for systemd to track it and avoids race conditions such as
this one:
systemd[1]: PID file /run/sshd.pid not readable (yet?) after start.
systemd[1]: Failed to start SSH Daemon.
systemd[1]: Unit sshd.service entered failed state.
systemd[1]: sshd.service holdoff time over, scheduling restart.
systemd[1]: Stopping SSH Daemon...
systemd[1]: Starting SSH Daemon...
sshd[2315]: Server listening on 0.0.0.0 port 22.
sshd[2315]: Server listening on :: port 22.
sshd[2335]: error: Bind to port 22 on 0.0.0.0 failed: Address already in use.
sshd[2335]: error: Bind to port 22 on :: failed: Address already in use.
sshd[2335]: fatal: Cannot bind any address.
systemd[1]: Started SSH Daemon.
Logind sessions are more generally useful than for device ownership.
For instances, ssh logins can be put in their own session (and thus
their own cgroup).
Subtle: dhcpcd.service would call resolvconf during shutdown, which in
turn would start invalidate-nscd.service, causing the shutdown to be
cancelled. Instead, give nscd.service a proper reload action, and do
"systemctl reload --no-block nscd.service". The --no-block is
necessary to prevent that command from waiting until a timeout occurs
(bug in systemd?).
This especially annoyed me whenver I was doing nixos-rebuild switch and getting
logged out on all consoles. With this there now is services.mingetty.dontRestart
for heavy VT users to deactivate this behaviour.
The option is disabled by default so that previously existing installations
aren't affected.
If you'd like to migrate to the fixed numeric id for Apache, set "fixUidAndGid
= true", edit the file "/etc/groups" and replace the old GID value with 54.
(NixOS can't do that for you because it refuses to change a GID that identifies
the primary group of a user.) Then run
find / -xdev -uid $oldUID -exec chown 54 {} +
find / -xdev -gid $oldGID -exec chgrp 54 {} +
to update ownership of all files that are supposed to be owned by Apache.
