This allows hiding the implementation details for how to represent logstash
config types that don't directly map to nix expressions, particularly floats,
hashes, and name-value pair sets with repeated names. Instead of setting
__type and value directly, the user now uses these convenience functions to
generate their logstash config.
Since the logstash config file seemed very similar to a nixexpr, I decided
to map directly from nixexprs to logstash configs. I didn't realize until
too far in that this solution was probably way over-engineered, but it
works.
The new option ‘skins’ allows specifying a list of directories
providing skins to be added to the MediaWiki installation. The
‘defaultSkin’ option just sets the default.
resolvconf prefers a locally running BIND resolver over the forwarders; we just
have to tell it whether we have one or not. We use 'config.services.bind.enable'
to make that decision, assuming that people are not going to configure a local
BIND that won't respond to queries on 127.0.0.1. If we run into such a (weird)
case, then we'll need to introduce another variable for that purpose which can
be set independently from 'config.services.bind.enable'.
BusyBox doesn't handle the "auto" filesystem type very well: fsck will
just ignore such filesystems, and mount will only work properly if the
required kernel module is already loaded. Therefore, use blkid to
determine the filesystem type.
Also generate an /etc/fstab in the initrd rootfs on the fly. This is
useful if you're dropped into an emergency shell since it allows you
to say "fsck /dev/sda1" or "mount /dev/sda" and have the right thing
happen.
So it turns out that BusyBox doesn't auto-load modules for filesystems
that have type "auto", e.g. it doesn't figure out that it should load
the "iso9660" module should be loaded when mounting the CD-ROM. We
don't want to give the root FS on the CD type "iso9660", because that
breaks booting from a USB stick created by unetbootin. So make sure
the "iso9660" module is loaded.
Using BusyBox instead of Bash plus a bunch of other tools gives us a
much more feature-full, yet smaller initrd. In particular, BusyBox
contains networking commands such as ip and a DHCP client, useful for
NFS boots. It's also much more convenient for rescue situations
because the shell has builtin readline support and there are many more
tools (including vi).
