git-subtree-dir: third_party/nixpkgs git-subtree-split: 76612b17c0ce71689921ca12d9ffdc9c23ce40b2
2.3 KiB
Building Specific Parts of NixOS
With the command nix-build
, you can build specific parts of your NixOS
configuration. This is done as follows:
$ cd /path/to/nixpkgs/nixos
$ nix-build -A config.option
where option
is a NixOS option with type "derivation" (i.e. something
that can be built). Attributes of interest include:
system.build.toplevel
-
The top-level option that builds the entire NixOS system. Everything else in your configuration is indirectly pulled in by this option. This is what
nixos-rebuild
builds and what/run/current-system
points to afterwards.A shortcut to build this is:
$ nix-build -A system
system.build.manual.manualHTML
-
The NixOS manual.
system.build.etc
-
A tree of symlinks that form the static parts of
/etc
. system.build.initialRamdisk
,system.build.kernel
-
The initial ramdisk and kernel of the system. This allows a quick way to test whether the kernel and the initial ramdisk boot correctly, by using QEMU's
-kernel
and-initrd
options:$ nix-build -A config.system.build.initialRamdisk -o initrd $ nix-build -A config.system.build.kernel -o kernel $ qemu-system-x86_64 -kernel ./kernel/bzImage -initrd ./initrd/initrd -hda /dev/null
system.build.nixos-rebuild
,system.build.nixos-install
,system.build.nixos-generate-config
-
These build the corresponding NixOS commands.
systemd.units.unit-name.unit
-
This builds the unit with the specified name. Note that since unit names contain dots (e.g.
httpd.service
), you need to put them between quotes, like this:$ nix-build -A 'config.systemd.units."httpd.service".unit'
You can also test individual units, without rebuilding the whole system, by putting them in
/run/systemd/system
:$ cp $(nix-build -A 'config.systemd.units."httpd.service".unit')/httpd.service \ /run/systemd/system/tmp-httpd.service # systemctl daemon-reload # systemctl start tmp-httpd.service
Note that the unit must not have the same name as any unit in
/etc/systemd/system
since those take precedence over/run/systemd/system
. That's why the unit is installed astmp-httpd.service
here.