nixpkgs/doc/configuration.xml
2018-11-19 13:02:17 -06:00

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<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xml:id="chap-packageconfig">
<title>Global configuration</title>
<para>
Nix comes with certain defaults about what packages can and cannot be
installed, based on a package's metadata. By default, Nix will prevent
installation if any of the following criteria are true:
</para>
<itemizedlist>
<listitem>
<para>
The package is thought to be broken, and has had its
<literal>meta.broken</literal> set to <literal>true</literal>.
</para>
</listitem>
<listitem>
<para>
The package isn't intended to run on the given system, as none of its
<literal>meta.platforms</literal> match the given system.
</para>
</listitem>
<listitem>
<para>
The package's <literal>meta.license</literal> is set to a license which is
considered to be unfree.
</para>
</listitem>
<listitem>
<para>
The package has known security vulnerabilities but has not or can not be
updated for some reason, and a list of issues has been entered in to the
package's <literal>meta.knownVulnerabilities</literal>.
</para>
</listitem>
</itemizedlist>
<para>
Note that all this is checked during evaluation already, and the check
includes any package that is evaluated. In particular, all build-time
dependencies are checked. <literal>nix-env -qa</literal> will (attempt to)
hide any packages that would be refused.
</para>
<para>
Each of these criteria can be altered in the nixpkgs configuration.
</para>
<para>
The nixpkgs configuration for a NixOS system is set in the
<literal>configuration.nix</literal>, as in the following example:
<programlisting>
{
nixpkgs.config = {
allowUnfree = true;
};
}
</programlisting>
However, this does not allow unfree software for individual users. Their
configurations are managed separately.
</para>
<para>
A user's of nixpkgs configuration is stored in a user-specific configuration
file located at <filename>~/.config/nixpkgs/config.nix</filename>. For
example:
<programlisting>
{
allowUnfree = true;
}
</programlisting>
</para>
<para>
Note that we are not able to test or build unfree software on Hydra due to
policy. Most unfree licenses prohibit us from either executing or
distributing the software.
</para>
<section xml:id="sec-allow-broken">
<title>Installing broken packages</title>
<para>
There are two ways to try compiling a package which has been marked as
broken.
</para>
<itemizedlist>
<listitem>
<para>
For allowing the build of a broken package once, you can use an
environment variable for a single invocation of the nix tools:
<programlisting>$ export NIXPKGS_ALLOW_BROKEN=1</programlisting>
</para>
</listitem>
<listitem>
<para>
For permanently allowing broken packages to be built, you may add
<literal>allowBroken = true;</literal> to your user's configuration file,
like this:
<programlisting>
{
allowBroken = true;
}
</programlisting>
</para>
</listitem>
</itemizedlist>
</section>
<section xml:id="sec-allow-unsupported-system">
<title>Installing packages on unsupported systems</title>
<para>
There are also two ways to try compiling a package which has been marked as
unsuported for the given system.
</para>
<itemizedlist>
<listitem>
<para>
For allowing the build of a broken package once, you can use an
environment variable for a single invocation of the nix tools:
<programlisting>$ export NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1</programlisting>
</para>
</listitem>
<listitem>
<para>
For permanently allowing broken packages to be built, you may add
<literal>allowUnsupportedSystem = true;</literal> to your user's
configuration file, like this:
<programlisting>
{
allowUnsupportedSystem = true;
}
</programlisting>
</para>
</listitem>
</itemizedlist>
<para>
The difference between a package being unsupported on some system and
being broken is admittedly a bit fuzzy. If a program
<emphasis>ought</emphasis> to work on a certain platform, but doesn't, the
platform should be included in <literal>meta.platforms</literal>, but marked
as broken with e.g. <literal>meta.broken =
!hostPlatform.isWindows</literal>. Of course, this begs the question of what
"ought" means exactly. That is left to the package maintainer.
</para>
</section>
<section xml:id="sec-allow-unfree">
<title>Installing unfree packages</title>
<para>
There are several ways to tweak how Nix handles a package which has been
marked as unfree.
</para>
<itemizedlist>
<listitem>
<para>
To temporarily allow all unfree packages, you can use an environment
variable for a single invocation of the nix tools:
<programlisting>$ export NIXPKGS_ALLOW_UNFREE=1</programlisting>
</para>
</listitem>
<listitem>
<para>
It is possible to permanently allow individual unfree packages, while
still blocking unfree packages by default using the
<literal>allowUnfreePredicate</literal> configuration option in the user
configuration file.
</para>
<para>
This option is a function which accepts a package as a parameter, and
returns a boolean. The following example configuration accepts a package
and always returns false:
<programlisting>
{
allowUnfreePredicate = (pkg: false);
}
</programlisting>
</para>
<para>
For a more useful example, try the following. This configuration
only allows unfree packages named flash player and visual studio
code:
<programlisting>
{
allowUnfreePredicate = (pkg: builtins.elem (builtins.parseDrvName pkg.name).name [ "flashplayer" "vscode" ]);
}
</programlisting>
</para>
</listitem>
<listitem>
<para>
It is also possible to whitelist and blacklist licenses that are
specifically acceptable or not acceptable, using
<literal>whitelistedLicenses</literal> and
<literal>blacklistedLicenses</literal>, respectively.
</para>
<para>
The following example configuration whitelists the licenses
<literal>amd</literal> and <literal>wtfpl</literal>:
<programlisting>
{
whitelistedLicenses = with stdenv.lib.licenses; [ amd wtfpl ];
}
</programlisting>
</para>
<para>
The following example configuration blacklists the <literal>gpl3</literal>
and <literal>agpl3</literal> licenses:
<programlisting>
{
blacklistedLicenses = with stdenv.lib.licenses; [ agpl3 gpl3 ];
}
</programlisting>
</para>
</listitem>
</itemizedlist>
<para>
A complete list of licenses can be found in the file
<filename>lib/licenses.nix</filename> of the nixpkgs tree.
</para>
</section>
<section xml:id="sec-allow-insecure">
<title>Installing insecure packages</title>
<para>
There are several ways to tweak how Nix handles a package which has been
marked as insecure.
</para>
<itemizedlist>
<listitem>
<para>
To temporarily allow all insecure packages, you can use an environment
variable for a single invocation of the nix tools:
<programlisting>$ export NIXPKGS_ALLOW_INSECURE=1</programlisting>
</para>
</listitem>
<listitem>
<para>
It is possible to permanently allow individual insecure packages, while
still blocking other insecure packages by default using the
<literal>permittedInsecurePackages</literal> configuration option in the
user configuration file.
</para>
<para>
The following example configuration permits the installation of the
hypothetically insecure package <literal>hello</literal>, version
<literal>1.2.3</literal>:
<programlisting>
{
permittedInsecurePackages = [
"hello-1.2.3"
];
}
</programlisting>
</para>
</listitem>
<listitem>
<para>
It is also possible to create a custom policy around which insecure
packages to allow and deny, by overriding the
<literal>allowInsecurePredicate</literal> configuration option.
</para>
<para>
The <literal>allowInsecurePredicate</literal> option is a function which
accepts a package and returns a boolean, much like
<literal>allowUnfreePredicate</literal>.
</para>
<para>
The following configuration example only allows insecure packages with
very short names:
<programlisting>
{
allowInsecurePredicate = (pkg: (builtins.stringLength (builtins.parseDrvName pkg.name).name) &lt;= 5);
}
</programlisting>
</para>
<para>
Note that <literal>permittedInsecurePackages</literal> is only checked if
<literal>allowInsecurePredicate</literal> is not specified.
</para>
</listitem>
</itemizedlist>
</section>
<!--============================================================-->
<section xml:id="sec-modify-via-packageOverrides">
<title>Modify packages via <literal>packageOverrides</literal></title>
<para>
You can define a function called <varname>packageOverrides</varname> in your
local <filename>~/.config/nixpkgs/config.nix</filename> to override Nix
packages. It must be a function that takes pkgs as an argument and returns a
modified set of packages.
<programlisting>
{
packageOverrides = pkgs: rec {
foo = pkgs.foo.override { ... };
};
}
</programlisting>
</para>
</section>
<section xml:id="sec-declarative-package-management">
<title>Declarative Package Management</title>
<section xml:id="sec-building-environment">
<title>Build an environment</title>
<para>
Using <literal>packageOverrides</literal>, it is possible to manage
packages declaratively. This means that we can list all of our desired
packages within a declarative Nix expression. For example, to have
<literal>aspell</literal>, <literal>bc</literal>,
<literal>ffmpeg</literal>, <literal>coreutils</literal>,
<literal>gdb</literal>, <literal>nixUnstable</literal>,
<literal>emscripten</literal>, <literal>jq</literal>,
<literal>nox</literal>, and <literal>silver-searcher</literal>, we could
use the following in <filename>~/.config/nixpkgs/config.nix</filename>:
</para>
<screen>
{
packageOverrides = pkgs: with pkgs; {
myPackages = pkgs.buildEnv {
name = "my-packages";
paths = [ aspell bc coreutils gdb ffmpeg nixUnstable emscripten jq nox silver-searcher ];
};
};
}
</screen>
<para>
To install it into our environment, you can just run <literal>nix-env -iA
nixpkgs.myPackages</literal>. If you want to load the packages to be built
from a working copy of <literal>nixpkgs</literal> you just run
<literal>nix-env -f. -iA myPackages</literal>. To explore what's been
installed, just look through <filename>~/.nix-profile/</filename>. You can
see that a lot of stuff has been installed. Some of this stuff is useful
some of it isn't. Let's tell Nixpkgs to only link the stuff that we want:
</para>
<screen>
{
packageOverrides = pkgs: with pkgs; {
myPackages = pkgs.buildEnv {
name = "my-packages";
paths = [ aspell bc coreutils gdb ffmpeg nixUnstable emscripten jq nox silver-searcher ];
pathsToLink = [ "/share" "/bin" ];
};
};
}
</screen>
<para>
<literal>pathsToLink</literal> tells Nixpkgs to only link the paths listed
which gets rid of the extra stuff in the profile. <filename>/bin</filename>
and <filename>/share</filename> are good defaults for a user environment,
getting rid of the clutter. If you are running on Nix on MacOS, you may
want to add another path as well, <filename>/Applications</filename>, that
makes GUI apps available.
</para>
</section>
<section xml:id="sec-getting-documentation">
<title>Getting documentation</title>
<para>
After building that new environment, look through
<filename>~/.nix-profile</filename> to make sure everything is there that
we wanted. Discerning readers will note that some files are missing. Look
inside <filename>~/.nix-profile/share/man/man1/</filename> to verify this.
There are no man pages for any of the Nix tools! This is because some
packages like Nix have multiple outputs for things like documentation (see
section 4). Let's make Nix install those as well.
</para>
<screen>
{
packageOverrides = pkgs: with pkgs; {
myPackages = pkgs.buildEnv {
name = "my-packages";
paths = [ aspell bc coreutils ffmpeg nixUnstable emscripten jq nox silver-searcher ];
pathsToLink = [ "/share/man" "/share/doc" "/bin" ];
extraOutputsToInstall = [ "man" "doc" ];
};
};
}
</screen>
<para>
This provides us with some useful documentation for using our packages.
However, if we actually want those manpages to be detected by man, we need
to set up our environment. This can also be managed within Nix expressions.
</para>
<screen>
{
packageOverrides = pkgs: with pkgs; rec {
myProfile = writeText "my-profile" ''
export PATH=$HOME/.nix-profile/bin:/nix/var/nix/profiles/default/bin:/sbin:/bin:/usr/sbin:/usr/bin
export MANPATH=$HOME/.nix-profile/share/man:/nix/var/nix/profiles/default/share/man:/usr/share/man
'';
myPackages = pkgs.buildEnv {
name = "my-packages";
paths = [
(runCommand "profile" {} ''
mkdir -p $out/etc/profile.d
cp ${myProfile} $out/etc/profile.d/my-profile.sh
'')
aspell
bc
coreutils
ffmpeg
man
nixUnstable
emscripten
jq
nox
silver-searcher
];
pathsToLink = [ "/share/man" "/share/doc" "/bin" "/etc" ];
extraOutputsToInstall = [ "man" "doc" ];
};
};
}
</screen>
<para>
For this to work fully, you must also have this script sourced when you are
logged in. Try adding something like this to your
<filename>~/.profile</filename> file:
</para>
<screen>
#!/bin/sh
if [ -d $HOME/.nix-profile/etc/profile.d ]; then
for i in $HOME/.nix-profile/etc/profile.d/*.sh; do
if [ -r $i ]; then
. $i
fi
done
fi
</screen>
<para>
Now just run <literal>source $HOME/.profile</literal> and you can starting
loading man pages from your environent.
</para>
</section>
<section xml:id="sec-gnu-info-setup">
<title>GNU info setup</title>
<para>
Configuring GNU info is a little bit trickier than man pages. To work
correctly, info needs a database to be generated. This can be done with
some small modifications to our environment scripts.
</para>
<screen>
{
packageOverrides = pkgs: with pkgs; rec {
myProfile = writeText "my-profile" ''
export PATH=$HOME/.nix-profile/bin:/nix/var/nix/profiles/default/bin:/sbin:/bin:/usr/sbin:/usr/bin
export MANPATH=$HOME/.nix-profile/share/man:/nix/var/nix/profiles/default/share/man:/usr/share/man
export INFOPATH=$HOME/.nix-profile/share/info:/nix/var/nix/profiles/default/share/info:/usr/share/info
'';
myPackages = pkgs.buildEnv {
name = "my-packages";
paths = [
(runCommand "profile" {} ''
mkdir -p $out/etc/profile.d
cp ${myProfile} $out/etc/profile.d/my-profile.sh
'')
aspell
bc
coreutils
ffmpeg
man
nixUnstable
emscripten
jq
nox
silver-searcher
texinfoInteractive
];
pathsToLink = [ "/share/man" "/share/doc" "/share/info" "/bin" "/etc" ];
extraOutputsToInstall = [ "man" "doc" "info" ];
postBuild = ''
if [ -x $out/bin/install-info -a -w $out/share/info ]; then
shopt -s nullglob
for i in $out/share/info/*.info $out/share/info/*.info.gz; do
$out/bin/install-info $i $out/share/info/dir
done
fi
'';
};
};
}
</screen>
<para>
<literal>postBuild</literal> tells Nixpkgs to run a command after building
the environment. In this case, <literal>install-info</literal> adds the
installed info pages to <literal>dir</literal> which is GNU info's default
root node. Note that <literal>texinfoInteractive</literal> is added to the
environment to give the <literal>install-info</literal> command.
</para>
</section>
</section>
</chapter>