310 lines
13 KiB
XML
310 lines
13 KiB
XML
<!-- vim: set expandtab ts=2 softtabstop=2 shiftwidth=2 smarttab textwidth=80 wrapmargin=2 -->
|
||
<section
|
||
xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude"
|
||
version="5.0"
|
||
xml:id="sec-installing-from-other-distro">
|
||
|
||
<title>Installing from another Linux distribution</title>
|
||
|
||
<para>
|
||
Because Nix (the package manager) & Nixpkgs (the Nix packages
|
||
collection) can both be installed on any (most?) Linux distributions,
|
||
they can be used to install NixOS in various creative ways. You can,
|
||
for instance:
|
||
</para>
|
||
|
||
<orderedlist>
|
||
<listitem><para>Install NixOS on another partition, from your existing
|
||
Linux distribution (without the use of a USB or optical
|
||
device!)</para></listitem>
|
||
|
||
<listitem><para>Install NixOS on the same partition (in place!), from
|
||
your existing non-NixOS Linux distribution using
|
||
<literal>NIXOS_LUSTRATE</literal>.</para></listitem>
|
||
|
||
<listitem><para>Install NixOS on your hard drive from the Live CD of
|
||
any Linux distribution.</para></listitem>
|
||
</orderedlist>
|
||
|
||
<para>The first steps to all these are the same:</para>
|
||
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>Install the Nix package manager:</para>
|
||
|
||
<para>Short version:</para>
|
||
|
||
<screen>
|
||
$ bash <(curl https://nixos.org/nix/install)
|
||
$ . $HOME/.nix-profile/etc/profile.d/nix.sh # …or open a fresh shell</screen>
|
||
|
||
<para>More details in the <link
|
||
xlink:href="https://nixos.org/nix/manual/#chap-quick-start">
|
||
Nix manual</link></para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Switch to the NixOS channel:</para>
|
||
|
||
<para>If you've just installed Nix on a non-NixOS distribution, you
|
||
will be on the <literal>nixpkgs</literal> channel by
|
||
default.</para>
|
||
|
||
<screen>
|
||
$ nix-channel --list
|
||
nixpkgs https://nixos.org/channels/nixpkgs-unstable</screen>
|
||
|
||
<para>As that channel gets released without running the NixOS
|
||
tests, it will be safer to use the <literal>nixos-*</literal>
|
||
channels instead:</para>
|
||
|
||
<screen>
|
||
$ nix-channel --add https://nixos.org/channels/nixos-<replaceable>version</replaceable> nixpkgs</screen>
|
||
|
||
<para>You may want to throw in a <literal>nix-channel
|
||
--update</literal> for good measure.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Install the NixOS installation tools:</para>
|
||
|
||
<para>You'll need <literal>nixos-generate-config</literal> and
|
||
<literal>nixos-install</literal> and we'll throw in some man
|
||
pages and <literal>nixos-enter</literal> just in case you want
|
||
to chroot into your NixOS partition. They are installed by
|
||
default on NixOS, but you don't have NixOS yet..</para>
|
||
|
||
<screen>$ nix-env -iE "_: with import <nixpkgs/nixos> { configuration = {}; }; with config.system.build; [ nixos-generate-config nixos-install nixos-enter manual.manpages ]"</screen>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<note><para>The following 5 steps are only for installing NixOS to
|
||
another partition. For installing NixOS in place using
|
||
<literal>NIXOS_LUSTRATE</literal>, skip ahead.</para></note>
|
||
|
||
<para>Prepare your target partition:</para>
|
||
|
||
<para>At this point it is time to prepare your target partition.
|
||
Please refer to the partitioning, file-system creation, and
|
||
mounting steps of <xref linkend="sec-installation" /></para>
|
||
|
||
<para>If you're about to install NixOS in place using
|
||
<literal>NIXOS_LUSTRATE</literal> there is nothing to do for
|
||
this step.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Generate your NixOS configuration:</para>
|
||
|
||
<screen>$ sudo `which nixos-generate-config` --root /mnt</screen>
|
||
|
||
<para>You'll probably want to edit the configuration files. Refer
|
||
to the <literal>nixos-generate-config</literal> step in <xref
|
||
linkend="sec-installation" /> for more information.</para>
|
||
|
||
<para>Consider setting up the NixOS bootloader to give you the
|
||
ability to boot on your existing Linux partition. For instance,
|
||
if you're using GRUB and your existing distribution is running
|
||
Ubuntu, you may want to add something like this to your
|
||
<literal>configuration.nix</literal>:</para>
|
||
|
||
<programlisting>
|
||
boot.loader.grub.extraEntries = ''
|
||
menuentry "Ubuntu" {
|
||
search --set=ubuntu --fs-uuid 3cc3e652-0c1f-4800-8451-033754f68e6e
|
||
configfile "($ubuntu)/boot/grub/grub.cfg"
|
||
}
|
||
'';</programlisting>
|
||
|
||
<para>(You can find the appropriate UUID for your partition in
|
||
<literal>/dev/disk/by-uuid</literal>)</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Create the <literal>nixbld</literal> group and user on your
|
||
original distribution:</para>
|
||
|
||
<screen>
|
||
$ sudo groupadd -g 30000 nixbld
|
||
$ sudo useradd -u 30000 -g nixbld -G nixbld nixbld</screen>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Download/build/install NixOS:</para>
|
||
|
||
<warning><para>Once you complete this step, you might no longer be
|
||
able to boot on existing systems without the help of a
|
||
rescue USB drive or similar.</para></warning>
|
||
|
||
<screen>$ sudo PATH="$PATH" NIX_PATH="$NIX_PATH" `which nixos-install` --root /mnt</screen>
|
||
|
||
<para>Again, please refer to the <literal>nixos-install</literal>
|
||
step in <xref linkend="sec-installation" /> for more
|
||
information.</para>
|
||
|
||
<para>That should be it for installation to another partition!</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Optionally, you may want to clean up your non-NixOS distribution:</para>
|
||
|
||
<screen>
|
||
$ sudo userdel nixbld
|
||
$ sudo groupdel nixbld</screen>
|
||
|
||
<para>If you do not wish to keep the Nix package mananager
|
||
installed either, run something like <literal>sudo rm -rv
|
||
~/.nix-* /nix</literal> and remove the line that the Nix
|
||
installer added to your <literal>~/.profile</literal>.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<note><para>The following steps are only for installing NixOS in
|
||
place using
|
||
<literal>NIXOS_LUSTRATE</literal>:</para></note>
|
||
|
||
<para>Generate your NixOS configuration:</para>
|
||
|
||
<screen>$ sudo `which nixos-generate-config` --root /</screen>
|
||
|
||
<para>Note that this will place the generated configuration files
|
||
in <literal>/etc/nixos</literal>. You'll probably want to edit
|
||
the configuration files. Refer to the
|
||
<literal>nixos-generate-config</literal> step in <xref
|
||
linkend="sec-installation" /> for more information.</para>
|
||
|
||
<para>You'll likely want to set a root password for your first boot
|
||
using the configuration files because you won't have a chance
|
||
to enter a password until after you reboot. You can initalize
|
||
the root password to an empty one with this line: (and of course
|
||
don't forget to set one once you've rebooted or to lock the
|
||
account with <literal>sudo passwd -l root</literal> if you use
|
||
<literal>sudo</literal>)</para>
|
||
|
||
<programlisting>users.extraUsers.root.initialHashedPassword = "";</programlisting>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Build the NixOS closure and install it in the
|
||
<literal>system</literal> profile:</para>
|
||
|
||
<screen>$ nix-env -p /nix/var/nix/profiles/system -f '<nixpkgs/nixos>' -I nixos-config=/etc/nixos/configuration.nix -iA system</screen>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Change ownership of the <literal>/nix</literal> tree to root
|
||
(since your Nix install was probably single user):</para>
|
||
|
||
<screen>$ sudo chown -R 0.0 /nix</screen>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Set up the <literal>/etc/NIXOS</literal> and
|
||
<literal>/etc/NIXOS_LUSTRATE</literal> files:</para>
|
||
|
||
<para><literal>/etc/NIXOS</literal> officializes that this is now a
|
||
NixOS partition (the bootup scripts require its presence).</para>
|
||
|
||
<para><literal>/etc/NIXOS_LUSTRATE</literal> tells the NixOS bootup
|
||
scripts to move <emphasis>everything</emphasis> that's in the
|
||
root partition to <literal>/old-root</literal>. This will move
|
||
your existing distribution out of the way in the very early
|
||
stages of the NixOS bootup. There are exceptions (we do need to
|
||
keep NixOS there after all), so the NixOS lustrate process will
|
||
not touch:</para>
|
||
|
||
<itemizedlist>
|
||
<listitem><para>The <literal>/nix</literal>
|
||
directory</para></listitem>
|
||
|
||
<listitem><para>The <literal>/boot</literal>
|
||
directory</para></listitem>
|
||
|
||
<listitem><para>Any file or directory listed in
|
||
<literal>/etc/NIXOS_LUSTRATE</literal> (one per
|
||
line)</para></listitem>
|
||
</itemizedlist>
|
||
|
||
<note><para>Support for <literal>NIXOS_LUSTRATE</literal> was added
|
||
in NixOS 16.09. The act of "lustrating" refers to the
|
||
wiping of the existing distribution. Creating
|
||
<literal>/etc/NIXOS_LUSTRATE</literal> can also be used on
|
||
NixOS to remove all mutable files from your root partition
|
||
(anything that's not in <literal>/nix</literal> or
|
||
<literal>/boot</literal> gets "lustrated" on the next
|
||
boot.</para>
|
||
<para>lustrate /ˈlʌstreɪt/ verb.</para>
|
||
<para>purify by expiatory sacrifice, ceremonial washing, or
|
||
some other ritual action.</para></note>
|
||
|
||
<para>Let's create the files:</para>
|
||
|
||
<screen>
|
||
$ sudo touch /etc/NIXOS
|
||
$ sudo touch /etc/NIXOS_LUSTRATE</screen>
|
||
|
||
<para>Let's also make sure the NixOS configuration files are kept
|
||
once we reboot on NixOS:</para>
|
||
|
||
<screen>
|
||
$ echo etc/nixos | sudo tee -a /etc/NIXOS_LUSTRATE</screen>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>Finally, move the <literal>/boot</literal> directory of your
|
||
current distribution out of the way (the lustrate process will
|
||
take care of the rest once you reboot, but this one must be
|
||
moved out now because NixOS needs to install its own boot
|
||
files:</para>
|
||
|
||
<warning><para>Once you complete this step, your current
|
||
distribution will no longer be bootable! If you didn't get
|
||
all the NixOS configuration right, especially those
|
||
settings pertaining to boot loading and root partition,
|
||
NixOS may not be bootable either. Have a USB rescue device
|
||
ready in case this happens. </para></warning>
|
||
|
||
<screen>
|
||
$ sudo mv -v /boot /boot.bak &&
|
||
sudo /nix/var/nix/profiles/system/bin/switch-to-configuration boot</screen>
|
||
|
||
<para>Cross your fingers, reboot, hopefully you should get a NixOS
|
||
prompt!</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>If for some reason you want to revert to the old
|
||
distribution, you'll need to boot on a USB rescue disk and do
|
||
something along these lines:</para>
|
||
|
||
<screen>
|
||
# mkdir root
|
||
# mount /dev/sdaX root
|
||
# mkdir root/nixos-root
|
||
# mv -v root/* root/nixos-root/
|
||
# mv -v root/nixos-root/old-root/* root/
|
||
# mv -v root/boot.bak root/boot # We had renamed this by hand earlier
|
||
# umount root
|
||
# reboot</screen>
|
||
|
||
<para>This may work as is or you might also need to reinstall the
|
||
boot loader</para>
|
||
|
||
<para>And of course, if you're happy with NixOS and no longer need
|
||
the old distribution:</para>
|
||
|
||
<screen>sudo rm -rf /old-root</screen>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>It's also worth noting that this whole process can be
|
||
automated. This is especially useful for Cloud VMs, where
|
||
provider do not provide NixOS. For instance, <link
|
||
xlink:href="https://github.com/elitak/nixos-infect">nixos-infect</link>
|
||
uses the lustrate process to convert Digital Ocean droplets to
|
||
NixOS from other distributions automatically.</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
</section>
|