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diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml new file mode 100644 index 000000000..d0f1b09ca --- /dev/null +++ b/doc/manual/command-ref/conf-file.xml @@ -0,0 +1,1236 @@ +<?xml version="1.0" encoding="utf-8"?> +<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" + version="5"> + +<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>By default Nix reads settings from the following places:</para> + +<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>$NIX_CONF_DIR/nix.conf</filename> if +<envar>NIX_CONF_DIR</envar> is set. Values loaded in this file are not forwarded to the Nix daemon. The +client assumes that the daemon has already loaded them. +</para> + +<para>User-specific configuration files:</para> + +<para> + If <envar>NIX_USER_CONF_FILES</envar> is set, then each path separated by + <literal>:</literal> will be loaded in reverse order. +</para> + +<para> + Otherwise it will look for <filename>nix/nix.conf</filename> files in + <envar>XDG_CONFIG_DIRS</envar> and <envar>XDG_CONFIG_HOME</envar>. + + The default location is <filename>$HOME/.config/nix.conf</filename> if + those environment variables are unset. +</para> + +<para>The configuration files consist of +<literal><replaceable>name</replaceable> = +<replaceable>value</replaceable></literal> pairs, one per line. Other +files can be included with a line like <literal>include +<replaceable>path</replaceable></literal>, where +<replaceable>path</replaceable> is interpreted relative to the current +conf file and a missing file is an error unless +<literal>!include</literal> is used instead. +Comments start with a <literal>#</literal> character. Here is an +example configuration file:</para> + +<programlisting> +keep-outputs = true # Nice for developers +keep-derivations = true # Idem +</programlisting> + +<para>You can override settings on the command line using the +<option>--option</option> flag, e.g. <literal>--option keep-outputs +false</literal>.</para> + +<para>The following settings are currently available: + +<variablelist> + + + <varlistentry xml:id="conf-allowed-uris"><term><literal>allowed-uris</literal></term> + + <listitem> + + <para>A list of URI prefixes to which access is allowed in + restricted evaluation mode. For example, when set to + <literal>https://github.com/NixOS</literal>, builtin functions + such as <function>fetchGit</function> are allowed to access + <literal>https://github.com/NixOS/patchelf.git</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>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> + + + <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-auto-optimise-store"><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-builders"> + <term><literal>builders</literal></term> + <listitem> + <para>A list of machines on which to perform builds. <phrase + condition="manual">See <xref linkend="chap-distributed-builds" + /> for details.</phrase></para> + </listitem> + </varlistentry> + + + <varlistentry xml:id="conf-builders-use-substitutes"><term><literal>builders-use-substitutes</literal></term> + + <listitem><para>If set to <literal>true</literal>, Nix will instruct + remote build machines to use their own binary substitutes if available. In + practical terms, this means that remote hosts will fetch as many build + dependencies as possible from their own substitutes (e.g, from + <literal>cache.nixos.org</literal>), instead of waiting for this host to + upload them all. This can drastically reduce build times if the network + connection between this computer and the remote build host is slow. Defaults + to <literal>false</literal>.</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 xml:id="conf-compress-build-log"><term><literal>compress-build-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 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-cores"><term><literal>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> + + <para>See also <xref linkend="chap-tuning-cores-and-jobs" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-diff-hook"><term><literal>diff-hook</literal></term> + <listitem> + <para> + Absolute path to an executable capable of diffing build results. + The hook executes if <xref linkend="conf-run-diff-hook" /> is + true, and the output of a build is known to not be the same. + This program is not executed to determine if two results are the + same. + </para> + + <para> + The diff hook is executed by the same user and group who ran the + build. However, the diff hook does not have write access to the + store path just built. + </para> + + <para>The diff hook program receives three parameters:</para> + + <orderedlist> + <listitem> + <para> + A path to the previous build's results + </para> + </listitem> + + <listitem> + <para> + A path to the current build's results + </para> + </listitem> + + <listitem> + <para> + The path to the build's derivation + </para> + </listitem> + + <listitem> + <para> + The path to the build's scratch directory. This directory + will exist only if the build was run with + <option>--keep-failed</option>. + </para> + </listitem> + </orderedlist> + + <para> + The stderr and stdout output from the diff hook will not be + displayed to the user. Instead, it will print to the nix-daemon's + log. + </para> + + <para>When using the Nix daemon, <literal>diff-hook</literal> must + be set in the <filename>nix.conf</filename> configuration file, and + cannot be passed at the command line. + </para> + </listitem> + </varlistentry> + + <varlistentry xml:id="conf-enforce-determinism"> + <term><literal>enforce-determinism</literal></term> + + <listitem><para>See <xref linkend="conf-repeat" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-extra-sandbox-paths"> + <term><literal>extra-sandbox-paths</literal></term> + + <listitem><para>A list of additional paths appended to + <option>sandbox-paths</option>. Useful if you want to extend + its default value.</para></listitem> + + </varlistentry> + + + <varlistentry xml:id="conf-extra-platforms"><term><literal>extra-platforms</literal></term> + + <listitem><para>Platforms other than the native one which + this machine is capable of building for. This can be useful for + supporting additional architectures on compatible machines: + i686-linux can be built on x86_64-linux machines (and the default + for this setting reflects this); armv7 is backwards-compatible with + armv6 and armv5tel; some aarch64 machines can also natively run + 32-bit ARM code; and qemu-user may be used to support non-native + platforms (though this may be slow and buggy). Most values for this + are not enabled by default because build systems will often + misdetect the target platform and generate incompatible code, so you + may wish to cross-check the results of using this option against + proper natively-built versions of your + derivations.</para></listitem> + + </varlistentry> + + + <varlistentry xml:id="conf-extra-substituters"><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 xml:id="conf-fallback"><term><literal>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 xml:id="conf-fsync-metadata"><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 xml:id="conf-hashed-mirrors"><term><literal>hashed-mirrors</literal></term> + + <listitem><para>A list of web servers used by + <function>builtins.fetchurl</function> to obtain files by hash. + Given a hash type <replaceable>ht</replaceable> and a base-16 hash + <replaceable>h</replaceable>, Nix will try to download the file + from + <literal>hashed-mirror/<replaceable>ht</replaceable>/<replaceable>h</replaceable></literal>. + This allows files to be downloaded even if they have disappeared + from their original URI. For example, given the hashed mirror + <literal>http://tarballs.example.com/</literal>, when building the + derivation + +<programlisting> +builtins.fetchurl { + url = "https://example.org/foo-1.2.3.tar.xz"; + sha256 = "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae"; +} +</programlisting> + + Nix will attempt to download this file from + <literal>http://tarballs.example.com/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae</literal> + first. If it is not available there, if will try the original URI.</para></listitem> + + </varlistentry> + + + <varlistentry xml:id="conf-http-connections"><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 xml:id="conf-keep-build-log"><term><literal>keep-build-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 xml:id="conf-keep-derivations"><term><literal>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>keep-outputs</literal> is also turned on).</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-keep-env-derivations"><term><literal>keep-env-derivations</literal></term> + + <listitem><para>If <literal>false</literal> (default), derivations + are not stored in Nix user environments. That is, the derivations of + 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>keep-outputs</literal>.</para> + + <para>The difference between this option and + <literal>keep-derivations</literal> is that this one is + “sticky”: it applies to any user environment created while this + option was enabled, while <literal>keep-derivations</literal> + only applies at the moment the garbage collector is + run.</para></listitem> + + </varlistentry> + + <varlistentry xml:id="conf-keep-outputs"><term><literal>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-max-build-log-size"><term><literal>max-build-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-max-free"><term><literal>max-free</literal></term> + + <listitem><para>When a garbage collection is triggered by the + <literal>min-free</literal> option, it stops as soon as + <literal>max-free</literal> bytes are available. The default is + infinity (i.e. delete all garbage).</para></listitem> + + </varlistentry> + + <varlistentry xml:id="conf-max-jobs"><term><literal>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. <literal>0</literal> + is useful when using remote builders to prevent any local builds (except for + <literal>preferLocalBuild</literal> derivation attribute which executes locally + regardless). It can be + overridden using the <option + linkend='opt-max-jobs'>--max-jobs</option> (<option>-j</option>) + command line switch.</para> + + <para>See also <xref linkend="chap-tuning-cores-and-jobs" />.</para> + </listitem> + </varlistentry> + + <varlistentry xml:id="conf-max-silent-time"><term><literal>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-min-free"><term><literal>min-free</literal></term> + + <listitem> + <para>When free disk space in <filename>/nix/store</filename> + drops below <literal>min-free</literal> during a build, Nix + performs a garbage-collection until <literal>max-free</literal> + bytes are available or there is no more garbage. A value of + <literal>0</literal> (the default) disables this feature.</para> + </listitem> + + </varlistentry> + + <varlistentry xml:id="conf-narinfo-cache-negative-ttl"><term><literal>narinfo-cache-negative-ttl</literal></term> + + <listitem> + + <para>The TTL in seconds for negative lookups. If a store path is + queried from a substituter but was not found, there will be a + negative lookup cached in the local disk cache database for the + specified duration.</para> + + </listitem> + + </varlistentry> + + <varlistentry xml:id="conf-narinfo-cache-positive-ttl"><term><literal>narinfo-cache-positive-ttl</literal></term> + + <listitem> + + <para>The TTL in seconds for positive lookups. If a store path is + queried from a substituter, the result of the query will be cached + in the local disk cache database including some of the NAR + metadata. The default TTL is a month, setting a shorter TTL for + positive lookups can be useful for binary caches that have + frequent garbage collection, in which case having a more frequent + cache invalidation would prevent trying to pull the path again and + failing with a hash mismatch if the build isn't reproducible. + </para> + + </listitem> + + </varlistentry> + + <varlistentry xml:id="conf-netrc-file"><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> + + <note><para>This must be an absolute path, and <literal>~</literal> + is not resolved. For example, <filename>~/.netrc</filename> won't + resolve to your home directory's <filename>.netrc</filename>.</para></note> + </listitem> + + </varlistentry> + + + <varlistentry xml:id="conf-plugin-files"> + <term><literal>plugin-files</literal></term> + <listitem> + <para> + A list of plugin files to be loaded by Nix. Each of these + files will be dlopened by Nix, allowing them to affect + execution through static initialization. In particular, these + plugins may construct static instances of RegisterPrimOp to + add new primops or constants to the expression language, + RegisterStoreImplementation to add new store implementations, + RegisterCommand to add new subcommands to the + <literal>nix</literal> command, and RegisterSetting to add new + nix config settings. See the constructors for those types for + more details. + </para> + <para> + Since these files are loaded into the same address space as + Nix itself, they must be DSOs compatible with the instance of + Nix running at the time (i.e. compiled against the same + headers, not linked to any incompatible libraries). They + should not be linked to any Nix libs directly, as those will + be available already at load time. + </para> + <para> + If an entry in the list is a directory, all files in the + directory are loaded as plugins (non-recursively). + </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>sandbox-paths</literal>.</para> + + </listitem> + + </varlistentry> + </variablelist> + </listitem> + + </varlistentry> + + <varlistentry xml:id="conf-post-build-hook"> + <term><literal>post-build-hook</literal></term> + <listitem> + <para>Optional. The path to a program to execute after each build.</para> + + <para>This option is only settable in the global + <filename>nix.conf</filename>, or on the command line by trusted + users.</para> + + <para>When using the nix-daemon, the daemon executes the hook as + <literal>root</literal>. If the nix-daemon is not involved, the + hook runs as the user executing the nix-build.</para> + + <itemizedlist> + <listitem><para>The hook executes after an evaluation-time build.</para></listitem> + <listitem><para>The hook does not execute on substituted paths.</para></listitem> + <listitem><para>The hook's output always goes to the user's terminal.</para></listitem> + <listitem><para>If the hook fails, the build succeeds but no further builds execute.</para></listitem> + <listitem><para>The hook executes synchronously, and blocks other builds from progressing while it runs.</para></listitem> + </itemizedlist> + + <para>The program executes with no arguments. The program's environment + contains the following environment variables:</para> + + <variablelist> + <varlistentry> + <term><envar>DRV_PATH</envar></term> + <listitem> + <para>The derivation for the built paths.</para> + <para>Example: + <literal>/nix/store/5nihn1a7pa8b25l9zafqaqibznlvvp3f-bash-4.4-p23.drv</literal> + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><envar>OUT_PATHS</envar></term> + <listitem> + <para>Output paths of the built derivation, separated by a space character.</para> + <para>Example: + <literal>/nix/store/zf5lbh336mnzf1nlswdn11g4n2m8zh3g-bash-4.4-p23-dev + /nix/store/rjxwxwv1fpn9wa2x5ssk5phzwlcv4mna-bash-4.4-p23-doc + /nix/store/6bqvbzjkcp9695dq0dpl5y43nvy37pq1-bash-4.4-p23-info + /nix/store/r7fng3kk3vlpdlh2idnrbn37vh4imlj2-bash-4.4-p23-man + /nix/store/xfghy8ixrhz3kyy6p724iv3cxji088dx-bash-4.4-p23</literal>. + </para> + </listitem> + </varlistentry> + </variablelist> + + <para>See <xref linkend="chap-post-build-hook" /> for an example + implementation.</para> + + </listitem> + </varlistentry> + + <varlistentry xml:id="conf-repeat"><term><literal>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 and <xref linkend="conf-enforce-determinism" /> is + true, 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-require-sigs"><term><literal>require-sigs</literal></term> + + <listitem><para>If set to <literal>true</literal> (the default), + any non-content-addressed path added or copied to the Nix store + (e.g. when substituting from a binary cache) must have a valid + signature, that is, be signed using one of the keys listed in + <option>trusted-public-keys</option> or + <option>secret-key-files</option>. Set to <literal>false</literal> + to disable signature checking.</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), or to URIs outside of + <option>allowed-uri</option>. The default is + <literal>false</literal>.</para> + + </listitem> + + </varlistentry> + + <varlistentry xml:id="conf-run-diff-hook"><term><literal>run-diff-hook</literal></term> + <listitem> + <para> + If true, enable the execution of <xref linkend="conf-diff-hook" />. + </para> + + <para> + When using the Nix daemon, <literal>run-diff-hook</literal> must + be set in the <filename>nix.conf</filename> configuration file, + and cannot be passed at the command line. + </para> + </listitem> + </varlistentry> + + <varlistentry xml:id="conf-sandbox"><term><literal>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-sandbox-paths'><literal>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 macOS. 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>true</literal> on Linux and + <literal>false</literal> on all other platforms.</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-sandbox-paths"> + <term><literal>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-secret-key-files"><term><literal>secret-key-files</literal></term> + + <listitem><para>A whitespace-separated list of files containing + secret (private) keys. These are used to sign locally-built + paths. They can be generated using <command>nix-store + --generate-binary-cache-key</command>. The corresponding public + key can be distributed to other users, who can add it to + <option>trusted-public-keys</option> in their + <filename>nix.conf</filename>.</para></listitem> + + </varlistentry> + + + <varlistentry xml:id="conf-show-trace"><term><literal>show-trace</literal></term> + + <listitem><para>Causes Nix to print out a stack trace in case of Nix + expression evaluation errors.</para></listitem> + + </varlistentry> + + + <varlistentry xml:id="conf-substitute"><term><literal>substitute</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 xml:id="conf-stalled-download-timeout"><term><literal>stalled-download-timeout</literal></term> + <listitem> + <para>The timeout (in seconds) for receiving data from servers + during download. Nix cancels idle downloads after this timeout's + duration.</para> + </listitem> + </varlistentry> + + <varlistentry xml:id="conf-substituters"><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 xml:id="conf-system"><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 xml:id="conf-system-features"><term><literal>system-features</literal></term> + + <listitem><para>A set of system “features” supported by this + machine, e.g. <literal>kvm</literal>. Derivations can express a + dependency on such features through the derivation attribute + <varname>requiredSystemFeatures</varname>. For example, the + attribute + +<programlisting> +requiredSystemFeatures = [ "kvm" ]; +</programlisting> + + ensures that the derivation can only be built on a machine with + the <literal>kvm</literal> feature.</para> + + <para>This setting by default includes <literal>kvm</literal> if + <filename>/dev/kvm</filename> is accessible, and the + pseudo-features <literal>nixos-test</literal>, + <literal>benchmark</literal> and <literal>big-parallel</literal> + that are used in Nixpkgs to route builds to specific + machines.</para> + + </listitem> + + </varlistentry> + + <varlistentry xml:id="conf-tarball-ttl"><term><literal>tarball-ttl</literal></term> + + <listitem> + <para>Default: <literal>3600</literal> seconds.</para> + + <para>The number of seconds a downloaded tarball is considered + fresh. If the cached tarball is stale, Nix will check whether + it is still up to date using the ETag header. Nix will download + a new version if the ETag header is unsupported, or the + cached ETag doesn't match. + </para> + + <para>Setting the TTL to <literal>0</literal> forces Nix to always + check if the tarball is up to date.</para> + + <para>Nix caches tarballs in + <filename>$XDG_CACHE_HOME/nix/tarballs</filename>.</para> + + <para>Files fetched via <envar>NIX_PATH</envar>, + <function>fetchGit</function>, <function>fetchMercurial</function>, + <function>fetchTarball</function>, and <function>fetchurl</function> + respect this TTL. + </para> + </listitem> + </varlistentry> + + <varlistentry xml:id="conf-timeout"><term><literal>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-trace-function-calls"><term><literal>trace-function-calls</literal></term> + + <listitem> + + <para>Default: <literal>false</literal>.</para> + + <para>If set to <literal>true</literal>, the Nix evaluator will + trace every function call. Nix will print a log message at the + "vomit" level for every function entrance and function exit.</para> + + <informalexample><screen> +function-trace entered undefined position at 1565795816999559622 +function-trace exited undefined position at 1565795816999581277 +function-trace entered /nix/store/.../example.nix:226:41 at 1565795253249935150 +function-trace exited /nix/store/.../example.nix:226:41 at 1565795253249941684 +</screen></informalexample> + + <para>The <literal>undefined position</literal> means the function + call is a builtin.</para> + + <para>Use the <literal>contrib/stack-collapse.py</literal> script + distributed with the Nix source code to convert the trace logs + in to a format suitable for <command>flamegraph.pl</command>.</para> + + </listitem> + + </varlistentry> + + <varlistentry xml:id="conf-trusted-public-keys"><term><literal>trusted-public-keys</literal></term> + + <listitem><para>A whitespace-separated list of public keys. When + paths are copied from another Nix store (such as a binary cache), + they must be signed with one of these keys. For example: + <literal>cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= + hydra.nixos.org-1:CNHJZBh9K4tP3EKF6FkkgeVYsS3ohTl+oS0Qa8bezVs=</literal>.</para></listitem> + + </varlistentry> + + <varlistentry xml:id="conf-trusted-substituters"><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 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>Adding a user to <option>trusted-users</option> + is essentially equivalent to giving that user root access to the + system. For example, the user can set + <option>sandbox-paths</option> and thereby obtain read access to + directories that are otherwise inacessible to + them.</para></warning> + + </listitem> + + </varlistentry> + +</variablelist> +</para> + +<refsection> + <title>Deprecated Settings</title> + +<para> + +<variablelist> + + <varlistentry xml:id="conf-binary-caches"> + <term><literal>binary-caches</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>binary-caches</literal> is now an alias to + <xref linkend="conf-substituters" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-binary-cache-public-keys"> + <term><literal>binary-cache-public-keys</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>binary-cache-public-keys</literal> is now an alias to + <xref linkend="conf-trusted-public-keys" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-compress-log"> + <term><literal>build-compress-log</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-compress-log</literal> is now an alias to + <xref linkend="conf-compress-build-log" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-cores"> + <term><literal>build-cores</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-cores</literal> is now an alias to + <xref linkend="conf-cores" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-extra-chroot-dirs"> + <term><literal>build-extra-chroot-dirs</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-extra-chroot-dirs</literal> is now an alias to + <xref linkend="conf-extra-sandbox-paths" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-extra-sandbox-paths"> + <term><literal>build-extra-sandbox-paths</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-extra-sandbox-paths</literal> is now an alias to + <xref linkend="conf-extra-sandbox-paths" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-fallback"> + <term><literal>build-fallback</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-fallback</literal> is now an alias to + <xref linkend="conf-fallback" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-max-jobs"> + <term><literal>build-max-jobs</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-max-jobs</literal> is now an alias to + <xref linkend="conf-max-jobs" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-max-log-size"> + <term><literal>build-max-log-size</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-max-log-size</literal> is now an alias to + <xref linkend="conf-max-build-log-size" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-max-silent-time"> + <term><literal>build-max-silent-time</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-max-silent-time</literal> is now an alias to + <xref linkend="conf-max-silent-time" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-repeat"> + <term><literal>build-repeat</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-repeat</literal> is now an alias to + <xref linkend="conf-repeat" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-timeout"> + <term><literal>build-timeout</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-timeout</literal> is now an alias to + <xref linkend="conf-timeout" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-use-chroot"> + <term><literal>build-use-chroot</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-use-chroot</literal> is now an alias to + <xref linkend="conf-sandbox" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-use-sandbox"> + <term><literal>build-use-sandbox</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-use-sandbox</literal> is now an alias to + <xref linkend="conf-sandbox" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-build-use-substitutes"> + <term><literal>build-use-substitutes</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>build-use-substitutes</literal> is now an alias to + <xref linkend="conf-substitute" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-gc-keep-derivations"> + <term><literal>gc-keep-derivations</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>gc-keep-derivations</literal> is now an alias to + <xref linkend="conf-keep-derivations" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-gc-keep-outputs"> + <term><literal>gc-keep-outputs</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>gc-keep-outputs</literal> is now an alias to + <xref linkend="conf-keep-outputs" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-env-keep-derivations"> + <term><literal>env-keep-derivations</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>env-keep-derivations</literal> is now an alias to + <xref linkend="conf-keep-env-derivations" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-extra-binary-caches"> + <term><literal>extra-binary-caches</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>extra-binary-caches</literal> is now an alias to + <xref linkend="conf-extra-substituters" />.</para></listitem> + </varlistentry> + + <varlistentry xml:id="conf-trusted-binary-caches"> + <term><literal>trusted-binary-caches</literal></term> + + <listitem><para><emphasis>Deprecated:</emphasis> + <literal>trusted-binary-caches</literal> is now an alias to + <xref linkend="conf-trusted-substituters" />.</para></listitem> + </varlistentry> +</variablelist> +</para> +</refsection> + +</refsection> + +</refentry> |