141 lines
5.2 KiB
XML
141 lines
5.2 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
version="5.0"
|
||
xml:id="sec-upgrading">
|
||
|
||
<title>Upgrading NixOS</title>
|
||
|
||
<para>The best way to keep your NixOS installation up to date is to
|
||
use one of the NixOS <emphasis>channels</emphasis>. A channel is a
|
||
Nix mechanism for distributing Nix expressions and associated
|
||
binaries. The NixOS channels are updated automatically from NixOS’s
|
||
Git repository after certain tests have passed and all packages have
|
||
been built. These channels are:
|
||
|
||
<itemizedlist>
|
||
<listitem>
|
||
<para><emphasis>Stable channels</emphasis>, such as <literal
|
||
xlink:href="https://nixos.org/channels/nixos-17.03">nixos-17.03</literal>.
|
||
These only get conservative bug fixes and package upgrades. For
|
||
instance, a channel update may cause the Linux kernel on your
|
||
system to be upgraded from 4.9.16 to 4.9.17 (a minor bug fix), but
|
||
not from 4.9.<replaceable>x</replaceable> to
|
||
4.11.<replaceable>x</replaceable> (a major change that has the
|
||
potential to break things). Stable channels are generally
|
||
maintained until the next stable branch is created.</para>
|
||
<para></para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>The <emphasis>unstable channel</emphasis>, <literal
|
||
xlink:href="https://nixos.org/channels/nixos-unstable">nixos-unstable</literal>.
|
||
This corresponds to NixOS’s main development branch, and may thus
|
||
see radical changes between channel updates. It’s not recommended
|
||
for production systems.</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para><emphasis>Small channels</emphasis>, such as <literal
|
||
xlink:href="https://nixos.org/channels/nixos-17.03-small">nixos-17.03-small</literal>
|
||
or <literal
|
||
xlink:href="https://nixos.org/channels/nixos-unstable-small">nixos-unstable-small</literal>. These
|
||
are identical to the stable and unstable channels described above,
|
||
except that they contain fewer binary packages. This means they
|
||
get updated faster than the regular channels (for instance, when a
|
||
critical security patch is committed to NixOS’s source tree), but
|
||
may require more packages to be built from source than
|
||
usual. They’re mostly intended for server environments and as such
|
||
contain few GUI applications.</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
|
||
To see what channels are available, go to <link
|
||
xlink:href="https://nixos.org/channels"/>. (Note that the URIs of the
|
||
various channels redirect to a directory that contains the channel’s
|
||
latest version and includes ISO images and VirtualBox
|
||
appliances.)</para>
|
||
|
||
<para>When you first install NixOS, you’re automatically subscribed to
|
||
the NixOS channel that corresponds to your installation source. For
|
||
instance, if you installed from a 17.03 ISO, you will be subscribed to
|
||
the <literal>nixos-17.03</literal> channel. To see which NixOS
|
||
channel you’re subscribed to, run the following as root:
|
||
|
||
<screen>
|
||
# nix-channel --list | grep nixos
|
||
nixos https://nixos.org/channels/nixos-unstable
|
||
</screen>
|
||
|
||
To switch to a different NixOS channel, do
|
||
|
||
<screen>
|
||
# nix-channel --add https://nixos.org/channels/<replaceable>channel-name</replaceable> nixos
|
||
</screen>
|
||
|
||
(Be sure to include the <literal>nixos</literal> parameter at the
|
||
end.) For instance, to use the NixOS 17.03 stable channel:
|
||
|
||
<screen>
|
||
# nix-channel --add https://nixos.org/channels/nixos-17.03 nixos
|
||
</screen>
|
||
|
||
If you have a server, you may want to use the “small” channel instead:
|
||
|
||
<screen>
|
||
# nix-channel --add https://nixos.org/channels/nixos-17.03-small nixos
|
||
</screen>
|
||
|
||
And if you want to live on the bleeding edge:
|
||
|
||
<screen>
|
||
# nix-channel --add https://nixos.org/channels/nixos-unstable nixos
|
||
</screen>
|
||
|
||
</para>
|
||
|
||
<para>You can then upgrade NixOS to the latest version in your chosen
|
||
channel by running
|
||
|
||
<screen>
|
||
# nixos-rebuild switch --upgrade
|
||
</screen>
|
||
|
||
which is equivalent to the more verbose <literal>nix-channel --update
|
||
nixos; nixos-rebuild switch</literal>.</para>
|
||
|
||
<note><para>Channels are set per user. This means that running <literal>
|
||
nix-channel --add</literal> as a non root user (or without sudo) will not
|
||
affect configuration in <literal>/etc/nixos/configuration.nix</literal>
|
||
</para></note>
|
||
|
||
<warning><para>It is generally safe to switch back and forth between
|
||
channels. The only exception is that a newer NixOS may also have a
|
||
newer Nix version, which may involve an upgrade of Nix’s database
|
||
schema. This cannot be undone easily, so in that case you will not be
|
||
able to go back to your original channel.</para></warning>
|
||
|
||
|
||
<section><title>Automatic Upgrades</title>
|
||
|
||
<para>You can keep a NixOS system up-to-date automatically by adding
|
||
the following to <filename>configuration.nix</filename>:
|
||
|
||
<programlisting>
|
||
system.autoUpgrade.enable = true;
|
||
</programlisting>
|
||
|
||
This enables a periodically executed systemd service named
|
||
<literal>nixos-upgrade.service</literal>. It runs
|
||
<command>nixos-rebuild switch --upgrade</command> to upgrade NixOS to
|
||
the latest version in the current channel. (To see when the service
|
||
runs, see <command>systemctl list-timers</command>.) You can also
|
||
specify a channel explicitly, e.g.
|
||
|
||
<programlisting>
|
||
system.autoUpgrade.channel = https://nixos.org/channels/nixos-17.03;
|
||
</programlisting>
|
||
|
||
</para>
|
||
|
||
</section>
|
||
|
||
|
||
</chapter>
|