113 lines
3.6 KiB
XML
113 lines
3.6 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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version="5.0"
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xml:id="sec-building-parts">
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<title>Building Specific Parts of NixOS</title>
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<para>With the command <command>nix-build</command>, you can build
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specific parts of your NixOS configuration. This is done as follows:
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<screen>
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$ cd <replaceable>/path/to/nixpkgs/nixos</replaceable>
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$ nix-build -A config.<replaceable>option</replaceable></screen>
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where <replaceable>option</replaceable> is a NixOS option with type
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“derivation” (i.e. something that can be built). Attributes of
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interest include:
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<variablelist>
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<varlistentry>
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<term><varname>system.build.toplevel</varname></term>
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<listitem>
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<para>The top-level option that builds the entire NixOS system.
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Everything else in your configuration is indirectly pulled in by
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this option. This is what <command>nixos-rebuild</command>
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builds and what <filename>/run/current-system</filename> points
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to afterwards.</para>
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<para>A shortcut to build this is:
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<screen>
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$ nix-build -A system</screen>
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>system.build.manual.manual</varname></term>
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<listitem><para>The NixOS manual.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>system.build.etc</varname></term>
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<listitem><para>A tree of symlinks that form the static parts of
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<filename>/etc</filename>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>system.build.initialRamdisk</varname></term>
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<term><varname>system.build.kernel</varname></term>
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<listitem>
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<para>The initial ramdisk and kernel of the system. This allows
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a quick way to test whether the kernel and the initial ramdisk
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boot correctly, by using QEMU’s <option>-kernel</option> and
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<option>-initrd</option> options:
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<screen>
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$ nix-build -A config.system.build.initialRamdisk -o initrd
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$ nix-build -A config.system.build.kernel -o kernel
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$ qemu-system-x86_64 -kernel ./kernel/bzImage -initrd ./initrd/initrd -hda /dev/null
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</screen>
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>system.build.nixos-rebuild</varname></term>
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<term><varname>system.build.nixos-install</varname></term>
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<term><varname>system.build.nixos-generate-config</varname></term>
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<listitem>
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<para>These build the corresponding NixOS commands.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>systemd.units.<replaceable>unit-name</replaceable>.unit</varname></term>
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<listitem>
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<para>This builds the unit with the specified name. Note that
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since unit names contain dots
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(e.g. <literal>httpd.service</literal>), you need to put them
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between quotes, like this:
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<screen>
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$ nix-build -A 'config.systemd.units."httpd.service".unit'
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</screen>
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You can also test individual units, without rebuilding the whole
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system, by putting them in
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<filename>/run/systemd/system</filename>:
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<screen>
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$ cp $(nix-build -A 'config.systemd.units."httpd.service".unit')/httpd.service \
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/run/systemd/system/tmp-httpd.service
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$ systemctl daemon-reload
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$ systemctl start tmp-httpd.service
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</screen>
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Note that the unit must not have the same name as any unit in
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<filename>/etc/systemd/system</filename> since those take
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precedence over <filename>/run/systemd/system</filename>.
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That’s why the unit is installed as
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<filename>tmp-httpd.service</filename> here.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</chapter> |