Previously this module created both /var/db/nscd and /run/nscd using
shell commands in a preStart script. Note that both of these paths are
hard-coded in the nscd source. (Well, the latter is actually
/var/run/nscd but /var/run is a symlink to /run so it works out the
same.)
/var/db/nscd is only used if the nscd.conf "persistent" option is turned
on for one or more databases, which it is not in our default config
file. I'm not even sure persistent mode can work under systemd, since
`nscd --shutdown` is not synchronous so systemd will always
unceremoniously kill nscd without reliably giving it time to mark the
databases as unused. Nonetheless, if someone wants to use that option,
they can ensure the directory exists using systemd.tmpfiles.rules.
systemd can create /run/nscd for us with the RuntimeDirectory directive,
with the added benefit of causing systemd to delete the directory on
service stop or restart. The default value of RuntimeDirectoryMode is
755, the same as the mode which this module was using before.
I don't think the `rm -f /run/nscd/nscd.pid` was necessary after NixOS
switched to systemd and used its PIDFile directive, because systemd
deletes the specified file after the service stops, and because the file
can't persist across reboots since /run is a tmpfs. Even if the file
still exists when nscd starts, it's only a problem if the pid it
contains has been reused by another process, which is unlikely. Anyway,
this change makes that deletion even less necessary, because now systemd
deletes the entire /run/nscd directory when the service stops.
This postStart step was introduced on 2014-04-24 with the comment that
"Nscd forks into the background before it's ready to accept
connections."
However, that was fixed upstream almost two months earlier, on
2014-03-03, with the comment that "This, along with setting the nscd
service type to forking in its systemd configuration file, allows
systemd to be certain that the nscd service is ready and is accepting
connections."
The fix was released several months later in glibc 2.20, which was
merged in NixOS sometime before 15.09, so it certainly should be safe to
remove this workaround by now.
Add an option to set the rc-manager parameter in NetworkManager.conf,
which controls how NetworkManager handles resolv.conf. This sets the
default rc-manager to "resolvconf", which solves #61490. It
additionally allows the user to change rc-manager without interference
from configuration activations.
There are many support questions when people add a new binary cache
and they suddenly lose nixos substitutions.
Most of the users want to keep that, so we're doing a breaking change.
Previously to disable all binary caches one had to do:
nix.binaryCache = [];
Now the same is possible via:
nix.binaryCache = lib.mkForce;
