mirror of
https://github.com/NixOS/nix.git
synced 2024-11-23 15:22:27 +00:00
392 lines
13 KiB
XML
392 lines
13 KiB
XML
<refentry xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude"
|
||
xml:id="sec-nix-push">
|
||
|
||
<refmeta>
|
||
<refentrytitle>nix-push</refentrytitle>
|
||
<manvolnum>1</manvolnum>
|
||
<refmiscinfo class="source">Nix</refmiscinfo>
|
||
<refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>nix-push</refname>
|
||
<refpurpose>generate a binary cache</refpurpose>
|
||
</refnamediv>
|
||
|
||
<refsynopsisdiv>
|
||
<cmdsynopsis>
|
||
<command>nix-push</command>
|
||
<arg choice='plain'><option>--dest</option> <replaceable>dest-dir</replaceable></arg>
|
||
<arg><option>--bzip2</option></arg>
|
||
<arg><option>--force</option></arg>
|
||
<arg><option>--link</option></arg>
|
||
<arg><option>--manifest</option></arg>
|
||
<arg><option>--manifest-path</option> <replaceable>filename</replaceable></arg>
|
||
<arg><option>--url-prefix</option> <replaceable>url</replaceable></arg>
|
||
<arg choice='plain' rep='repeat'><replaceable>paths</replaceable></arg>
|
||
</cmdsynopsis>
|
||
</refsynopsisdiv>
|
||
|
||
|
||
<refsection><title>Description</title>
|
||
|
||
<para>The command <command>nix-push</command> produces a
|
||
<emphasis>binary cache</emphasis>, a directory containing compressed
|
||
Nix archives (NARs) plus some metadata of the closure of the specified
|
||
store paths. This directory can then be made available through a web
|
||
server to other Nix installations, allowing them to skip building from
|
||
source and instead download binaries from the cache
|
||
automatically.</para>
|
||
|
||
<para><command>nix-push</command> performs the following actions.
|
||
|
||
<orderedlist>
|
||
|
||
<listitem><para>Each path in <replaceable>paths</replaceable> is
|
||
built (using <link
|
||
linkend='rsec-nix-store-realise'><command>nix-store
|
||
--realise</command></link>).</para></listitem>
|
||
|
||
<listitem><para>All paths in the closure of
|
||
<replaceable>paths</replaceable> are determined (using
|
||
<command>nix-store --query --requisites
|
||
--include-outputs</command>). Note that since the
|
||
<option>--include-outputs</option> flag is used, if
|
||
<replaceable>paths</replaceable> includes a store derivation, you
|
||
get a combined source/binary distribution (e.g., source tarballs
|
||
will be included).</para></listitem>
|
||
|
||
<listitem><para>All store paths determined in the previous step are
|
||
packaged into a NAR (using <command>nix-store --dump</command>) and
|
||
compressed using <command>xz</command> or <command>bzip2</command>.
|
||
The resulting files have the extension <filename>.nar.xz</filename>
|
||
or <filename>.nar.bz2</filename>. Also for each store path, Nix
|
||
generates a file with extension <filename>.narinfo</filename>
|
||
containing metadata such as the references, cryptographic hash and
|
||
size of each path.</para></listitem>
|
||
|
||
<listitem><para>Optionally, a single <emphasis>manifest</emphasis>
|
||
file is created that contains the same metadata as the
|
||
<filename>.narinfo</filename> files. This is for compatibility with
|
||
Nix versions prior to 1.2 (see <command>nix-pull</command> for
|
||
details).</para></listitem>
|
||
|
||
<listitem><para>A file named <option>nix-cache-info</option> is
|
||
placed in the destination directory. The existence of this file
|
||
marks the directory as a binary cache.</para></listitem>
|
||
|
||
</orderedlist>
|
||
|
||
</para>
|
||
|
||
</refsection>
|
||
|
||
|
||
<refsection><title>Options</title>
|
||
|
||
<variablelist>
|
||
|
||
<varlistentry><term><option>--dest</option> <replaceable>dest-dir</replaceable></term>
|
||
|
||
<listitem><para>Set the destination directory to
|
||
<replaceable>dir</replaceable>, which is created if it does not
|
||
exist. This flag is required.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><option>--bzip2</option></term>
|
||
|
||
<listitem><para>Compress NARs using <command>bzip2</command>
|
||
instead of <command>xz -9</command>. The latter compresses about
|
||
30% better on typical archives, decompresses about twice as fast,
|
||
but compresses a lot slower and is not supported by Nix prior to
|
||
version 1.2.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><option>--force</option></term>
|
||
|
||
<listitem><para>Overwrite <filename>.narinfo</filename> files if
|
||
they already exist.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><option>--link</option></term>
|
||
|
||
<listitem><para>By default, NARs are generated in the Nix store
|
||
and then copied to <replaceable>dest-dir</replaceable>. If this
|
||
option is given, hard links are used instead. This only works if
|
||
<replaceable>dest-dir</replaceable> is on the same filesystem as
|
||
the Nix store.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><option>--manifest</option></term>
|
||
|
||
<listitem><para>Force the generation of a manifest suitable for
|
||
use by <command>nix-pull</command>. The manifest is stored as
|
||
<filename><replaceable>dest-dir</replaceable>/MANIFEST</filename>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><option>--manifest-path</option> <replaceable>filename</replaceable></term>
|
||
|
||
<listitem><para>Like <option>--manifest</option>, but store the
|
||
manifest in <replaceable>filename</replaceable>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><option>--url-prefix</option> <replaceable>url</replaceable></term>
|
||
|
||
<listitem><para>Manifests are expected to contain the absolute
|
||
URLs of NARs. For generating these URLs, the prefix
|
||
<replaceable>url</replaceable> is used. It defaults to
|
||
<uri>file://<replaceable>dest-dir</replaceable></uri>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
</variablelist>
|
||
|
||
</refsection>
|
||
|
||
|
||
<refsection><title>Examples</title>
|
||
|
||
<para>To add the closure of Thunderbird to a binary cache:
|
||
|
||
<screen>
|
||
$ nix-push --dest /tmp/cache $(nix-build -A thunderbird)
|
||
</screen>
|
||
|
||
Assuming that <filename>/tmp/cache</filename> is exported by a web
|
||
server as <uri>http://example.org/cache</uri>, you can then use this
|
||
cache on another machine to speed up the installation of Thunderbird:
|
||
|
||
<screen>
|
||
$ nix-build -A thunderbird --option binary-caches http://example.org/cache
|
||
</screen>
|
||
|
||
Alternatively, you could add <literal>binary-caches =
|
||
http://example.org/cache</literal> to
|
||
<filename>nix.conf</filename>.</para>
|
||
|
||
<para>To also include build-time dependencies (such as source
|
||
tarballs):
|
||
|
||
<screen>
|
||
$ nix-push --dest /tmp/cache $(nix-instantiate -A thunderbird)
|
||
</screen>
|
||
|
||
</para>
|
||
|
||
<para>To generate a manifest suitable for <command>nix-pull</command>:
|
||
|
||
<screen>
|
||
$ nix-push --dest /tmp/cache $(nix-build -A thunderbird) --manifest
|
||
</screen>
|
||
|
||
On another machine you can then do:
|
||
|
||
<screen>
|
||
$ nix-pull http://example.org/cache
|
||
</screen>
|
||
|
||
to cause the binaries to be used by subsequent Nix operations.</para>
|
||
|
||
</refsection>
|
||
|
||
|
||
<refsection><title>Binary cache format and operation</title>
|
||
|
||
<para>A binary cache with URL <replaceable>url</replaceable> only
|
||
denotes a valid binary cache if the file
|
||
<uri><replaceable>url</replaceable>/nix-cache-info</uri> exists. If
|
||
this file does not exist (or cannot be downloaded), the cache is
|
||
ignored. If it does exist, it must be a text file containing cache
|
||
properties. Here’s an example:
|
||
|
||
<screen>
|
||
StoreDir: /nix/store
|
||
WantMassQuery: 1
|
||
Priority: 10
|
||
</screen>
|
||
|
||
The properties that are currently supported are:
|
||
|
||
<variablelist>
|
||
|
||
<varlistentry><term><literal>StoreDir</literal></term>
|
||
|
||
<listitem><para>The path of the Nix store to which this binary
|
||
cache applies. Binaries are not relocatable — a binary built for
|
||
<filename>/nix/store</filename> won’t generally work in
|
||
<filename>/home/alice/store</filename> — so to prevent binaries
|
||
from being used in a wrong store, a binary cache is only used if
|
||
its <literal>StoreDir</literal> matches the local Nix
|
||
configuration. The default is
|
||
<filename>/nix/store</filename>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>WantMassQuery</literal></term>
|
||
|
||
<listitem><para>Query operations such as <command>nix-env
|
||
-qas</command> can cause thousands of cache queries, and thus
|
||
thousands of HTTP requests, to determine which packages are
|
||
available in binary form. While these requests are small, not
|
||
every server may appreciate a potential onslaught of queries. If
|
||
<literal>WantMassQuery</literal> is set to <literal>0</literal>
|
||
(default), “mass queries” such as <command>nix-env -qas</command>
|
||
will skip this cache. Thus a package may appear not to have a
|
||
binary substitute. However, the binary will still be used when
|
||
you actually install the package. If
|
||
<literal>WantMassQuery</literal> is set to <literal>1</literal>,
|
||
mass queries will use this cache.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>Priority</literal></term>
|
||
|
||
<listitem><para>Each binary cache has a priority (defaulting to
|
||
50). Binary caches are checked for binaries in order of ascending
|
||
priority; thus a higher number denotes a lower priority. The
|
||
binary cache <uri>http://nixos.org/binary-cache</uri> has priority
|
||
40.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
</variablelist>
|
||
|
||
</para>
|
||
|
||
<para>Every time Nix needs to build some store path
|
||
<replaceable>p</replaceable>, it will check each configured binary
|
||
cache to see if it has a NAR file for <replaceable>p</replaceable>,
|
||
until it finds one. If no cache has a NAR, Nix will fall back to
|
||
building the path from source (if applicable). To see if a cache with
|
||
URL <replaceable>url</replaceable> has a binary for
|
||
<replaceable>p</replaceable>, Nix fetches
|
||
<replaceable>url/h</replaceable>, where <replaceable>h</replaceable>
|
||
is the hash part of <replaceable>p</replaceable>. Thus, if we have a
|
||
cache <uri>http://nixos.org/binary-cache</uri> and we want to obtain
|
||
the store path
|
||
<screen>
|
||
/nix/store/a8922c0h87iilxzzvwn2hmv8x210aqb9-glibc-2.7
|
||
</screen>
|
||
then Nix will attempt to fetch
|
||
<screen>
|
||
http://nixos.org/binary-cache/a8922c0h87iilxzzvwn2hmv8x210aqb9.narinfo
|
||
</screen>
|
||
(Commands such as <command>nix-env -qas</command> will issue an HTTP
|
||
HEAD request, since it only needs to know if the
|
||
<filename>.narinfo</filename> file exists.) The
|
||
<filename>.narinfo</filename> file is a simple text file that looks
|
||
like this:
|
||
|
||
<screen>
|
||
StorePath: /nix/store/a8922c0h87iilxzzvwn2hmv8x210aqb9-glibc-2.7
|
||
URL: nar/0zzjpdz46mdn74v09m053yczlz4am038g8r74iy8w43gx8801h70.nar.bz2
|
||
Compression: bzip2
|
||
FileHash: sha256:0zzjpdz46mdn74v09m053yczlz4am038g8r74iy8w43gx8801h70
|
||
FileSize: 24473768
|
||
NarHash: sha256:0s491y1h9hxj5ghiizlxk7ax6jwbha00zwn7lpyd5xg5bhf60vzg
|
||
NarSize: 109521136
|
||
References: 2ma2k0ys8knh4an48n28vigcmc2z8773-linux-headers-2.6.23.16 ...
|
||
Deriver: 7akyyc87ka32xwmqza9dvyg5pwx3j212-glibc-2.7.drv
|
||
</screen>
|
||
|
||
The fields are as follows:
|
||
|
||
<variablelist>
|
||
|
||
<varlistentry><term><literal>StorePath</literal></term>
|
||
|
||
<listitem><para>The full store path, including the name part
|
||
(e.g., <literal>glibc-2.7</literal>). It must match the
|
||
requested store path.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>URL</literal></term>
|
||
|
||
<listitem><para>The URL of the NAR, relative to the binary cache
|
||
URL.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>Compression</literal></term>
|
||
|
||
<listitem><para>The compression method; either
|
||
<literal>xz</literal> or
|
||
<literal>bzip2</literal>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>FileHash</literal></term>
|
||
|
||
<listitem><para>The SHA-256 hash of the compressed
|
||
NAR.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>FileSize</literal></term>
|
||
|
||
<listitem><para>The size of the compressed NAR.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>NarHash</literal></term>
|
||
|
||
<listitem><para>The SHA-256 hash of the uncompressed NAR. This is
|
||
equal to the hash of the store path as returned by
|
||
<command>nix-store -q --hash
|
||
<replaceable>p</replaceable></command>.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>NarSize</literal></term>
|
||
|
||
<listitem><para>The size of the uncompressed NAR.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>References</literal></term>
|
||
|
||
<listitem><para>The references of the store path, without the Nix
|
||
store prefix.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>Deriver</literal></term>
|
||
|
||
<listitem><para>The deriver of the store path, without the Nix
|
||
store prefix. This field is optional.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry><term><literal>System</literal></term>
|
||
|
||
<listitem><para>The Nix platform type of this binary, if known.
|
||
This field is optional.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
</variablelist>
|
||
|
||
</para>
|
||
|
||
<para>Thus, in our example, after recursively ensuring that the
|
||
references exist (e.g.,
|
||
<filename>/nix/store/2ma2k0ys8knh4an48n28vigcmc2z8773-linux-headers-2.6.23.16</filename>),
|
||
Nix will fetch <screen>
|
||
http://nixos.org/binary-cache/nar/0zzjpdz46mdn74v09m053yczlz4am038g8r74iy8w43gx8801h70.nar.bz2
|
||
</screen> and decompress and unpack it to
|
||
<filename>/nix/store/a8922c0h87iilxzzvwn2hmv8x210aqb9-glibc-2.7</filename>.</para>
|
||
|
||
</refsection>
|
||
|
||
|
||
</refentry>
|