6cf23c3e8f
This allows builds to call setuid binaries. This was previously
possible until we started using seccomp. Turns out that seccomp by
default disallows processes from acquiring new privileges. Generally,
any use of setuid binaries (except those created by the builder
itself) is by definition impure, but some people were relying on this
ability for certain tests.
Example:
$ nix build '(with import <nixpkgs> {}; runCommand "foo" {} "/run/wrappers/bin/ping -c 1 8.8.8.8; exit 1")' --no-allow-new-privileges
builder for ‘/nix/store/j0nd8kv85hd6r4kxgnwzvr0k65ykf6fv-foo.drv’ failed with exit code 1; last 2 log lines:
cannot raise the capability into the Ambient set
: Operation not permitted
$ nix build '(with import <nixpkgs> {}; runCommand "foo" {} "/run/wrappers/bin/ping -c 1 8.8.8.8; exit 1")' --allow-new-privileges
builder for ‘/nix/store/j0nd8kv85hd6r4kxgnwzvr0k65ykf6fv-foo.drv’ failed with exit code 1; last 6 log lines:
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=46 time=15.2 ms
Fixes #1429.
670 lines
25 KiB
XML
670 lines
25 KiB
XML
<refentry xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude"
|
||
xml:id="sec-conf-file">
|
||
|
||
<refmeta>
|
||
<refentrytitle>nix.conf</refentrytitle>
|
||
<manvolnum>5</manvolnum>
|
||
<refmiscinfo class="source">Nix</refmiscinfo>
|
||
<refmiscinfo class="version"><xi:include href="../version.txt" parse="text"/></refmiscinfo>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>nix.conf</refname>
|
||
<refpurpose>Nix configuration file</refpurpose>
|
||
</refnamediv>
|
||
|
||
<refsection><title>Description</title>
|
||
|
||
<para>Nix reads settings from two configuration files:</para>
|
||
|
||
<itemizedlist>
|
||
|
||
<listitem>
|
||
<para>The system-wide configuration file
|
||
<filename><replaceable>sysconfdir</replaceable>/nix/nix.conf</filename>
|
||
(i.e. <filename>/etc/nix/nix.conf</filename> on most systems), or
|
||
<filename>$NIX_CONF_DIR/nix.conf</filename> if
|
||
<envar>NIX_CONF_DIR</envar> is set.</para>
|
||
</listitem>
|
||
|
||
<listitem>
|
||
<para>The user configuration file
|
||
<filename>$XDG_CONFIG_HOME/nix/nix.conf</filename>, or
|
||
<filename>~/.config/nix/nix.conf</filename> if
|
||
<envar>XDG_CONFIG_HOME</envar> is not set.</para>
|
||
</listitem>
|
||
|
||
</itemizedlist>
|
||
|
||
<para>The configuration files consist of
|
||
<literal><replaceable>name</replaceable> =
|
||
<replaceable>value</replaceable></literal> pairs, one per line.
|
||
Comments start with a <literal>#</literal> character. Here is an
|
||
example configuration file:</para>
|
||
|
||
<programlisting>
|
||
gc-keep-outputs = true # Nice for developers
|
||
gc-keep-derivations = true # Idem
|
||
env-keep-derivations = false
|
||
</programlisting>
|
||
|
||
<para>You can override settings on the command line using the
|
||
<option>--option</option> flag, e.g. <literal>--option gc-keep-outputs
|
||
false</literal>.</para>
|
||
|
||
<para>The following settings are currently available:
|
||
|
||
<variablelist>
|
||
|
||
|
||
<varlistentry xml:id="conf-gc-keep-outputs"><term><literal>gc-keep-outputs</literal></term>
|
||
|
||
<listitem><para>If <literal>true</literal>, the garbage collector
|
||
will keep the outputs of non-garbage derivations. If
|
||
<literal>false</literal> (default), outputs will be deleted unless
|
||
they are GC roots themselves (or reachable from other roots).</para>
|
||
|
||
<para>In general, outputs must be registered as roots separately.
|
||
However, even if the output of a derivation is registered as a
|
||
root, the collector will still delete store paths that are used
|
||
only at build time (e.g., the C compiler, or source tarballs
|
||
downloaded from the network). To prevent it from doing so, set
|
||
this option to <literal>true</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-gc-keep-derivations"><term><literal>gc-keep-derivations</literal></term>
|
||
|
||
<listitem><para>If <literal>true</literal> (default), the garbage
|
||
collector will keep the derivations from which non-garbage store
|
||
paths were built. If <literal>false</literal>, they will be
|
||
deleted unless explicitly registered as a root (or reachable from
|
||
other roots).</para>
|
||
|
||
<para>Keeping derivation around is useful for querying and
|
||
traceability (e.g., it allows you to ask with what dependencies or
|
||
options a store path was built), so by default this option is on.
|
||
Turn it off to save a bit of disk space (or a lot if
|
||
<literal>gc-keep-outputs</literal> is also turned on).</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>env-keep-derivations</literal></term>
|
||
|
||
<listitem><para>If <literal>false</literal> (default), derivations
|
||
are not stored in Nix user environments. That is, the derivation
|
||
any build-time-only dependencies may be garbage-collected.</para>
|
||
|
||
<para>If <literal>true</literal>, when you add a Nix derivation to
|
||
a user environment, the path of the derivation is stored in the
|
||
user environment. Thus, the derivation will not be
|
||
garbage-collected until the user environment generation is deleted
|
||
(<command>nix-env --delete-generations</command>). To prevent
|
||
build-time-only dependencies from being collected, you should also
|
||
turn on <literal>gc-keep-outputs</literal>.</para>
|
||
|
||
<para>The difference between this option and
|
||
<literal>gc-keep-derivations</literal> is that this one is
|
||
“sticky”: it applies to any user environment created while this
|
||
option was enabled, while <literal>gc-keep-derivations</literal>
|
||
only applies at the moment the garbage collector is
|
||
run.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-max-jobs"><term><literal>build-max-jobs</literal></term>
|
||
|
||
<listitem><para>This option defines the maximum number of jobs
|
||
that Nix will try to build in parallel. The default is
|
||
<literal>1</literal>. The special value <literal>auto</literal>
|
||
causes Nix to use the number of CPUs in your system. It can be
|
||
overridden using the <option
|
||
linkend='opt-max-jobs'>--max-jobs</option> (<option>-j</option>)
|
||
command line switch.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-cores"><term><literal>build-cores</literal></term>
|
||
|
||
<listitem><para>Sets the value of the
|
||
<envar>NIX_BUILD_CORES</envar> environment variable in the
|
||
invocation of builders. Builders can use this variable at their
|
||
discretion to control the maximum amount of parallelism. For
|
||
instance, in Nixpkgs, if the derivation attribute
|
||
<varname>enableParallelBuilding</varname> is set to
|
||
<literal>true</literal>, the builder passes the
|
||
<option>-j<replaceable>N</replaceable></option> flag to GNU Make.
|
||
It can be overridden using the <option
|
||
linkend='opt-cores'>--cores</option> command line switch and
|
||
defaults to <literal>1</literal>. The value <literal>0</literal>
|
||
means that the builder should use all available CPU cores in the
|
||
system.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-max-silent-time"><term><literal>build-max-silent-time</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>This option defines the maximum number of seconds that a
|
||
builder can go without producing any data on standard output or
|
||
standard error. This is useful (for instance in an automated
|
||
build system) to catch builds that are stuck in an infinite
|
||
loop, or to catch remote builds that are hanging due to network
|
||
problems. It can be overridden using the <option
|
||
linkend="opt-max-silent-time">--max-silent-time</option> command
|
||
line switch.</para>
|
||
|
||
<para>The value <literal>0</literal> means that there is no
|
||
timeout. This is also the default.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-timeout"><term><literal>build-timeout</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>This option defines the maximum number of seconds that a
|
||
builder can run. This is useful (for instance in an automated
|
||
build system) to catch builds that are stuck in an infinite loop
|
||
but keep writing to their standard output or standard error. It
|
||
can be overridden using the <option
|
||
linkend="opt-timeout">--timeout</option> command line
|
||
switch.</para>
|
||
|
||
<para>The value <literal>0</literal> means that there is no
|
||
timeout. This is also the default.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-max-log-size"><term><literal>build-max-log-size</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>This option defines the maximum number of bytes that a
|
||
builder can write to its stdout/stderr. If the builder exceeds
|
||
this limit, it’s killed. A value of <literal>0</literal> (the
|
||
default) means that there is no limit.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-users-group"><term><literal>build-users-group</literal></term>
|
||
|
||
<listitem><para>This options specifies the Unix group containing
|
||
the Nix build user accounts. In multi-user Nix installations,
|
||
builds should not be performed by the Nix account since that would
|
||
allow users to arbitrarily modify the Nix store and database by
|
||
supplying specially crafted builders; and they cannot be performed
|
||
by the calling user since that would allow him/her to influence
|
||
the build result.</para>
|
||
|
||
<para>Therefore, if this option is non-empty and specifies a valid
|
||
group, builds will be performed under the user accounts that are a
|
||
member of the group specified here (as listed in
|
||
<filename>/etc/group</filename>). Those user accounts should not
|
||
be used for any other purpose!</para>
|
||
|
||
<para>Nix will never run two builds under the same user account at
|
||
the same time. This is to prevent an obvious security hole: a
|
||
malicious user writing a Nix expression that modifies the build
|
||
result of a legitimate Nix expression being built by another user.
|
||
Therefore it is good to have as many Nix build user accounts as
|
||
you can spare. (Remember: uids are cheap.)</para>
|
||
|
||
<para>The build users should have permission to create files in
|
||
the Nix store, but not delete them. Therefore,
|
||
<filename>/nix/store</filename> should be owned by the Nix
|
||
account, its group should be the group specified here, and its
|
||
mode should be <literal>1775</literal>.</para>
|
||
|
||
<para>If the build users group is empty, builds will be performed
|
||
under the uid of the Nix process (that is, the uid of the caller
|
||
if <envar>NIX_REMOTE</envar> is empty, the uid under which the Nix
|
||
daemon runs if <envar>NIX_REMOTE</envar> is
|
||
<literal>daemon</literal>). Obviously, this should not be used in
|
||
multi-user settings with untrusted users.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>build-use-sandbox</literal></term>
|
||
|
||
<listitem><para>If set to <literal>true</literal>, builds will be
|
||
performed in a <emphasis>sandboxed environment</emphasis>, i.e.,
|
||
they’re isolated from the normal file system hierarchy and will
|
||
only see their dependencies in the Nix store, the temporary build
|
||
directory, private versions of <filename>/proc</filename>,
|
||
<filename>/dev</filename>, <filename>/dev/shm</filename> and
|
||
<filename>/dev/pts</filename> (on Linux), and the paths configured with the
|
||
<link linkend='conf-build-sandbox-paths'><literal>build-sandbox-paths</literal>
|
||
option</link>. This is useful to prevent undeclared dependencies
|
||
on files in directories such as <filename>/usr/bin</filename>. In
|
||
addition, on Linux, builds run in private PID, mount, network, IPC
|
||
and UTS namespaces to isolate them from other processes in the
|
||
system (except that fixed-output derivations do not run in private
|
||
network namespace to ensure they can access the network).</para>
|
||
|
||
<para>Currently, sandboxing only work on Linux and Mac OS X. The use
|
||
of a sandbox requires that Nix is run as root (so you should use
|
||
the <link linkend='conf-build-users-group'>“build users”
|
||
feature</link> to perform the actual builds under different users
|
||
than root).</para>
|
||
|
||
<para>If this option is set to <literal>relaxed</literal>, then
|
||
fixed-output derivations and derivations that have the
|
||
<varname>__noChroot</varname> attribute set to
|
||
<literal>true</literal> do not run in sandboxes.</para>
|
||
|
||
<para>The default is <literal>false</literal>.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-sandbox-paths">
|
||
<term><literal>build-sandbox-paths</literal></term>
|
||
|
||
<listitem><para>A list of paths bind-mounted into Nix sandbox
|
||
environments. You can use the syntax
|
||
<literal><replaceable>target</replaceable>=<replaceable>source</replaceable></literal>
|
||
to mount a path in a different location in the sandbox; for
|
||
instance, <literal>/bin=/nix-bin</literal> will mount the path
|
||
<literal>/nix-bin</literal> as <literal>/bin</literal> inside the
|
||
sandbox. If <replaceable>source</replaceable> is followed by
|
||
<literal>?</literal>, then it is not an error if
|
||
<replaceable>source</replaceable> does not exist; for example,
|
||
<literal>/dev/nvidiactl?</literal> specifies that
|
||
<filename>/dev/nvidiactl</filename> will only be mounted in the
|
||
sandbox if it exists in the host filesystem.</para>
|
||
|
||
<para>Depending on how Nix was built, the default value for this option
|
||
may be empty or provide <filename>/bin/sh</filename> as a
|
||
bind-mount of <command>bash</command>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-extra-sandbox-paths">
|
||
<term><literal>build-extra-sandbox-paths</literal></term>
|
||
|
||
<listitem><para>A list of additional paths appended to
|
||
<option>build-sandbox-paths</option>. Useful if you want to extend
|
||
its default value.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>build-use-substitutes</literal></term>
|
||
|
||
<listitem><para>If set to <literal>true</literal> (default), Nix
|
||
will use binary substitutes if available. This option can be
|
||
disabled to force building from source.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>build-fallback</literal></term>
|
||
|
||
<listitem><para>If set to <literal>true</literal>, Nix will fall
|
||
back to building from source if a binary substitute fails. This
|
||
is equivalent to the <option>--fallback</option> flag. The
|
||
default is <literal>false</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>build-keep-log</literal></term>
|
||
|
||
<listitem><para>If set to <literal>true</literal> (the default),
|
||
Nix will write the build log of a derivation (i.e. the standard
|
||
output and error of its builder) to the directory
|
||
<filename>/nix/var/log/nix/drvs</filename>. The build log can be
|
||
retrieved using the command <command>nix-store -l
|
||
<replaceable>path</replaceable></command>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>build-compress-log</literal></term>
|
||
|
||
<listitem><para>If set to <literal>true</literal> (the default),
|
||
build logs written to <filename>/nix/var/log/nix/drvs</filename>
|
||
will be compressed on the fly using bzip2. Otherwise, they will
|
||
not be compressed.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>substituters</literal></term>
|
||
|
||
<listitem><para>A list of URLs of substituters, separated by
|
||
whitespace. The default is
|
||
<literal>https://cache.nixos.org</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<!--
|
||
<varlistentry><term><literal>binary-caches-files</literal></term>
|
||
|
||
<listitem><para>A list of names of files that will be read to
|
||
obtain additional binary cache URLs. The default is
|
||
<literal>/nix/var/nix/profiles/per-user/<replaceable>username</replaceable>/channels/binary-caches/*</literal>.
|
||
Note that when you’re using the Nix daemon,
|
||
<replaceable>username</replaceable> is always equal to
|
||
<literal>root</literal>, so Nix will only use the binary caches
|
||
provided by the channels installed by root. Do not set this
|
||
option to read files created by untrusted users!</para></listitem>
|
||
|
||
</varlistentry>
|
||
-->
|
||
|
||
|
||
<varlistentry><term><literal>trusted-substituters</literal></term>
|
||
|
||
<listitem><para>A list of URLs of substituters, separated by
|
||
whitespace. These are not used by default, but can be enabled by
|
||
users of the Nix daemon by specifying <literal>--option
|
||
substituters <replaceable>urls</replaceable></literal> on the
|
||
command line. Unprivileged users are only allowed to pass a
|
||
subset of the URLs listed in <literal>substituters</literal> and
|
||
<literal>trusted-substituters</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>extra-substituters</literal></term>
|
||
|
||
<listitem><para>Additional binary caches appended to those
|
||
specified in <option>substituters</option>. When used by
|
||
unprivileged users, untrusted substituters (i.e. those not listed
|
||
in <option>trusted-substituters</option>) are silently
|
||
ignored.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>signed-binary-caches</literal></term>
|
||
|
||
<listitem><para>If set to <literal>*</literal> (the default), Nix
|
||
will only download binaries if they are signed using one of the
|
||
keys listed in <option>binary-cache-public-keys</option>. Set to
|
||
the empty string to disable signature checking.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>binary-cache-public-keys</literal></term>
|
||
|
||
<listitem><para>A whitespace-separated list of public keys
|
||
corresponding to the secret keys trusted to sign binary
|
||
caches. For example:
|
||
<literal>cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
|
||
hydra.nixos.org-1:CNHJZBh9K4tP3EKF6FkkgeVYsS3ohTl+oS0Qa8bezVs=</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>http-connections</literal></term>
|
||
|
||
<listitem><para>The maximum number of parallel TCP connections
|
||
used to fetch files from binary caches and by other downloads. It
|
||
defaults to 25. 0 means no limit.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>netrc-file</literal></term>
|
||
|
||
<listitem><para>If set to an absolute path to a <filename>netrc</filename>
|
||
file, Nix will use the HTTP authentication credentials in this file when
|
||
trying to download from a remote host through HTTP or HTTPS. Defaults to
|
||
<filename>$NIX_CONF_DIR/netrc</filename>.</para>
|
||
|
||
<para>The <filename>netrc</filename> file consists of a list of
|
||
accounts in the following format:
|
||
|
||
<screen>
|
||
machine <replaceable>my-machine</replaceable>
|
||
login <replaceable>my-username</replaceable>
|
||
password <replaceable>my-password</replaceable>
|
||
</screen>
|
||
|
||
For the exact syntax, see <link
|
||
xlink:href="https://ec.haxx.se/usingcurl-netrc.html">the
|
||
<literal>curl</literal> documentation.</link></para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>system</literal></term>
|
||
|
||
<listitem><para>This option specifies the canonical Nix system
|
||
name of the current installation, such as
|
||
<literal>i686-linux</literal> or
|
||
<literal>x86_64-darwin</literal>. Nix can only build derivations
|
||
whose <literal>system</literal> attribute equals the value
|
||
specified here. In general, it never makes sense to modify this
|
||
value from its default, since you can use it to ‘lie’ about the
|
||
platform you are building on (e.g., perform a Mac OS build on a
|
||
Linux machine; the result would obviously be wrong). It only
|
||
makes sense if the Nix binaries can run on multiple platforms,
|
||
e.g., ‘universal binaries’ that run on <literal>x86_64-linux</literal> and
|
||
<literal>i686-linux</literal>.</para>
|
||
|
||
<para>It defaults to the canonical Nix system name detected by
|
||
<filename>configure</filename> at build time.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>fsync-metadata</literal></term>
|
||
|
||
<listitem><para>If set to <literal>true</literal>, changes to the
|
||
Nix store metadata (in <filename>/nix/var/nix/db</filename>) are
|
||
synchronously flushed to disk. This improves robustness in case
|
||
of system crashes, but reduces performance. The default is
|
||
<literal>true</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry><term><literal>auto-optimise-store</literal></term>
|
||
|
||
<listitem><para>If set to <literal>true</literal>, Nix
|
||
automatically detects files in the store that have identical
|
||
contents, and replaces them with hard links to a single copy.
|
||
This saves disk space. If set to <literal>false</literal> (the
|
||
default), you can still run <command>nix-store
|
||
--optimise</command> to get rid of duplicate
|
||
files.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-connect-timeout"><term><literal>connect-timeout</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>The timeout (in seconds) for establishing connections in
|
||
the binary cache substituter. It corresponds to
|
||
<command>curl</command>’s <option>--connect-timeout</option>
|
||
option.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-trusted-users"><term><literal>trusted-users</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>A list of names of users (separated by whitespace) that
|
||
have additional rights when connecting to the Nix daemon, such
|
||
as the ability to specify additional binary caches, or to import
|
||
unsigned NARs. You can also specify groups by prefixing them
|
||
with <literal>@</literal>; for instance,
|
||
<literal>@wheel</literal> means all users in the
|
||
<literal>wheel</literal> group. The default is
|
||
<literal>root</literal>.</para>
|
||
|
||
<warning><para>The users listed here have the ability to
|
||
compromise the security of a multi-user Nix store. For instance,
|
||
they could install Trojan horses subsequently executed by other
|
||
users. So you should consider carefully whether to add users to
|
||
this list.</para></warning>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-allowed-users"><term><literal>allowed-users</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>A list of names of users (separated by whitespace) that
|
||
are allowed to connect to the Nix daemon. As with the
|
||
<option>trusted-users</option> option, you can specify groups by
|
||
prefixing them with <literal>@</literal>. Also, you can allow
|
||
all users by specifying <literal>*</literal>. The default is
|
||
<literal>*</literal>.</para>
|
||
|
||
<para>Note that trusted users are always allowed to connect.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-restrict-eval"><term><literal>restrict-eval</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>If set to <literal>true</literal>, the Nix evaluator will
|
||
not allow access to any files outside of the Nix search path (as
|
||
set via the <envar>NIX_PATH</envar> environment variable or the
|
||
<option>-I</option> option). The default is
|
||
<literal>false</literal>.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-pre-build-hook"><term><literal>pre-build-hook</literal></term>
|
||
|
||
<listitem>
|
||
|
||
|
||
<para>If set, the path to a program that can set extra
|
||
derivation-specific settings for this system. This is used for settings
|
||
that can't be captured by the derivation model itself and are too variable
|
||
between different versions of the same system to be hard-coded into nix.
|
||
</para>
|
||
|
||
<para>The hook is passed the derivation path and, if sandboxes are enabled,
|
||
the sandbox directory. It can then modify the sandbox and send a series of
|
||
commands to modify various settings to stdout. The currently recognized
|
||
commands are:</para>
|
||
|
||
<variablelist>
|
||
<varlistentry xml:id="extra-sandbox-paths">
|
||
<term><literal>extra-sandbox-paths</literal></term>
|
||
|
||
<listitem>
|
||
|
||
<para>Pass a list of files and directories to be included in the
|
||
sandbox for this build. One entry per line, terminated by an empty
|
||
line. Entries have the same format as
|
||
<literal>build-sandbox-paths</literal>.</para>
|
||
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
</variablelist>
|
||
</listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-build-repeat"><term><literal>build-repeat</literal></term>
|
||
|
||
<listitem><para>How many times to repeat builds to check whether
|
||
they are deterministic. The default value is 0. If the value is
|
||
non-zero, every build is repeated the specified number of
|
||
times. If the contents of any of the runs differs from the
|
||
previous ones, the build is rejected and the resulting store paths
|
||
are not registered as “valid” in Nix’s database.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-sandbox-dev-shm-size"><term><literal>sandbox-dev-shm-size</literal></term>
|
||
|
||
<listitem><para>This option determines the maximum size of the
|
||
<literal>tmpfs</literal> filesystem mounted on
|
||
<filename>/dev/shm</filename> in Linux sandboxes. For the format,
|
||
see the description of the <option>size</option> option of
|
||
<literal>tmpfs</literal> in
|
||
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>. The
|
||
default is <literal>50%</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-allow-import-from-derivation"><term><literal>allow-import-from-derivation</literal></term>
|
||
|
||
<listitem><para>By default, Nix allows you to <function>import</function> from a derivation,
|
||
allowing building at evaluation time. With this option set to false, Nix will throw an error
|
||
when evaluating an expression that uses this feature, allowing users to ensure their evaluation
|
||
will not require any builds to take place.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
<varlistentry xml:id="conf-allow-new-privileges"><term><literal>allow-new-privileges</literal></term>
|
||
|
||
<listitem><para>(Linux-specific.) By default, builders on Linux
|
||
cannot acquire new privileges by calling setuid/setgid programs or
|
||
programs that have file capabilities. For example, programs such
|
||
as <command>sudo</command> or <command>ping</command> will
|
||
fail. (Note that in sandbox builds, no such programs are available
|
||
unless you bind-mount them into the sandbox via the
|
||
<option>build-sandbox-paths</option> option.) You can allow the
|
||
use of such programs by enabling this option. This is impure and
|
||
usually undesirable, but may be useful in certain scenarios
|
||
(e.g. to spin up containers or set up userspace network interfaces
|
||
in tests).</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
|
||
</variablelist>
|
||
|
||
</para>
|
||
|
||
</refsection>
|
||
|
||
</refentry>
|