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Diffstat (limited to 'doc/manual/command-ref/conf-file.xml')
| -rw-r--r-- | doc/manual/command-ref/conf-file.xml | 821 |
1 files changed, 426 insertions, 395 deletions
diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml index fff7994f2..c76640c97 100644 --- a/doc/manual/command-ref/conf-file.xml +++ b/doc/manual/command-ref/conf-file.xml @@ -40,7 +40,12 @@ <para>The configuration files consist of <literal><replaceable>name</replaceable> = -<replaceable>value</replaceable></literal> pairs, one per line. +<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> @@ -58,147 +63,99 @@ false</literal>.</para> <variablelist> - <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-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><term><literal>keep-env-derivations</literal></term> + <varlistentry xml:id="conf-allowed-uris"><term><literal>allowed-uris</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> + <listitem> - <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>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> - <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> + </listitem> </varlistentry> - <varlistentry xml:id="conf-max-jobs"><term><literal>max-jobs</literal></term> + <varlistentry xml:id="conf-allow-import-from-derivation"><term><literal>allow-import-from-derivation</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> + <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-cores"><term><literal>cores</literal></term> + <varlistentry xml:id="conf-allow-new-privileges"><term><literal>allow-new-privileges</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> + <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-max-silent-time"><term><literal>max-silent-time</literal></term> + <varlistentry xml:id="conf-allowed-users"><term><literal>allowed-users</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>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>The value <literal>0</literal> means that there is no - timeout. This is also the default.</para> + <para>Note that trusted users are always allowed to connect.</para> </listitem> </varlistentry> - <varlistentry xml:id="conf-timeout"><term><literal>timeout</literal></term> + <varlistentry><term><literal>auto-optimise-store</literal></term> - <listitem> + <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> - <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> + </varlistentry> - <para>The value <literal>0</literal> means that there is no - timeout. This is also the default.</para> + <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-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> + <varlistentry><term><literal>builders-use-substitutes</literal></term> - </listitem> + <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> @@ -244,66 +201,51 @@ false</literal>.</para> </varlistentry> - <varlistentry><term><literal>sandbox</literal></term> + <varlistentry><term><literal>compress-build-log</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> + <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> - <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> + </varlistentry> - <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> + <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-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> + <varlistentry xml:id="conf-cores"><term><literal>cores</literal></term> - <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> + <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-extra-sandbox-paths"> - <term><literal>build-extra-sandbox-paths</literal></term> + <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 @@ -312,25 +254,13 @@ false</literal>.</para> </varlistentry> - <varlistentry><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><term><literal>builders-use-substitutes</literal></term> + <varlistentry><term><literal>extra-substituters</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> + <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> @@ -345,119 +275,168 @@ false</literal>.</para> </varlistentry> - <varlistentry><term><literal>keep-build-log</literal></term> + <varlistentry><term><literal>fsync-metadata</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> + <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>compress-build-log</literal></term> + <varlistentry xml:id="conf-hashed-mirrors"><term><literal>hashed-mirrors</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> + <listitem><para>A list of web servers used by + <function>builtins.fetchurl</function> to obtain files by + hash. The default is + <literal>http://tarballs.nixos.org/</literal>. 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 default mirror + <literal>http://tarballs.nixos.org/</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.nixos.org/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae</literal> + first. If it is not available there, if will try the original URI.</para></listitem> </varlistentry> - <varlistentry><term><literal>substituters</literal></term> + <varlistentry><term><literal>http-connections</literal></term> - <listitem><para>A list of URLs of substituters, separated by - whitespace. The default is - <literal>https://cache.nixos.org</literal>.</para></listitem> + <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>binary-caches-files</literal></term> + <varlistentry><term><literal>keep-build-log</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> + <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>trusted-substituters</literal></term> + <varlistentry xml:id="conf-keep-derivations"><term><literal>keep-derivations</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> + <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><term><literal>extra-substituters</literal></term> + <varlistentry><term><literal>keep-env-derivations</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> + <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>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><term><literal>require-sigs</literal></term> + <varlistentry xml:id="conf-keep-outputs"><term><literal>keep-outputs</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> + <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><term><literal>trusted-public-keys</literal></term> + <varlistentry xml:id="conf-max-build-log-size"><term><literal>max-build-log-size</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> + <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><term><literal>secret-key-files</literal></term> + <varlistentry xml:id="conf-max-jobs"><term><literal>max-jobs</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> + <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><term><literal>http-connections</literal></term> + <varlistentry xml:id="conf-max-silent-time"><term><literal>max-silent-time</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> + <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> @@ -485,104 +464,95 @@ password <replaceable>my-password</replaceable> </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 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><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-pre-build-hook"><term><literal>pre-build-hook</literal></term> + <listitem> - <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> + <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> - </varlistentry> + <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> - <varlistentry xml:id="conf-connect-timeout"><term><literal>connect-timeout</literal></term> + <listitem> - <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> - <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> + </variablelist> </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> + <varlistentry xml:id="conf-repeat"><term><literal>repeat</literal></term> - </listitem> + <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-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> + <varlistentry><term><literal>require-sigs</literal></term> - </listitem> + <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> @@ -603,141 +573,202 @@ password <replaceable>my-password</replaceable> </varlistentry> - <varlistentry xml:id="conf-allowed-uris"><term><literal>allowed-uris</literal></term> + <varlistentry><term><literal>sandbox</literal></term> - <listitem> + <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>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> + <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>false</literal>.</para> </listitem> </varlistentry> - <varlistentry xml:id="conf-pre-build-hook"><term><literal>pre-build-hook</literal></term> + <varlistentry xml:id="conf-sandbox-dev-shm-size"><term><literal>sandbox-dev-shm-size</literal></term> - <listitem> + <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> - <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> + <varlistentry xml:id="conf-sandbox-paths"> + <term><literal>sandbox-paths</literal></term> - <variablelist> - <varlistentry xml:id="extra-sandbox-paths"> - <term><literal>extra-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> - <listitem> + <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> - <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> + </varlistentry> - </listitem> - </varlistentry> - </variablelist> - </listitem> + <varlistentry><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-repeat"><term><literal>repeat</literal></term> + <varlistentry xml:id="conf-show-trace"><term><literal>show-trace</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> + <listitem><para>Causes Nix to print out a stack trace in case of Nix + expression evaluation errors.</para></listitem> </varlistentry> - <varlistentry xml:id="conf-sandbox-dev-shm-size"><term><literal>sandbox-dev-shm-size</literal></term> + <varlistentry><term><literal>substitute</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> + <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-allow-import-from-derivation"><term><literal>allow-import-from-derivation</literal></term> + <varlistentry><term><literal>substituters</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> + <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-allow-new-privileges"><term><literal>allow-new-privileges</literal></term> + <varlistentry><term><literal>system</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> + <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-hashed-mirrors"><term><literal>hashed-mirrors</literal></term> + <varlistentry xml:id="conf-timeout"><term><literal>timeout</literal></term> - <listitem><para>A list of web servers used by - <function>builtins.fetchurl</function> to obtain files by - hash. The default is - <literal>http://tarballs.nixos.org/</literal>. 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 default mirror - <literal>http://tarballs.nixos.org/</literal>, when building the derivation + <listitem> -<programlisting> -builtins.fetchurl { - url = https://example.org/foo-1.2.3.tar.xz; - sha256 = "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae"; -} -</programlisting> + <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> - Nix will attempt to download this file from - <literal>http://tarballs.nixos.org/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae</literal> - first. If it is not available there, if will try the original URI.</para></listitem> + <para>The value <literal>0</literal> means that there is no + timeout. This is also the default.</para> + + </listitem> </varlistentry> - <varlistentry xml:id="conf-show-trace"><term><literal>show-trace</literal></term> + <varlistentry><term><literal>trusted-public-keys</literal></term> - <listitem><para>Causes Nix to print out a stack trace in case of Nix - expression evaluation errors.</para></listitem> + <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><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> |