nix-gh/doc/manual/release-notes/rl-2.2.xml
2019-01-10 21:02:09 +01:00

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<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0"
xml:id="ssec-relnotes-2.2">
<title>Release 2.2 (2019-01-11)</title>
<para>This is primarily a bug fix release. It also has the following
changes:</para>
<itemizedlist>
<listitem>
<para>In derivations that use structured attributes (i.e. that
specify set the <varname>__structuredAttrs</varname> attribute to
<literal>true</literal> to cause all attributes to be passed to
the builder in JSON format), you can now specify closure checks
per output, e.g.:
<programlisting>
outputChecks."out" = {
# The closure of 'out' must not be larger than 256 MiB.
maxClosureSize = 256 * 1024 * 1024;
# It must not refer to C compiler or to the 'dev' output.
disallowedRequisites = [ stdenv.cc "dev" ];
};
outputChecks."dev" = {
# The 'dev' output must not be larger than 128 KiB.
maxSize = 128 * 1024;
};
</programlisting>
</para>
</listitem>
<listitem>
<para>The derivation attribute
<varname>requiredSystemFeatures</varname> is now enforced for
local builds, and not just to route builds to remote builders.
The supported features of a machine can be specified through the
configuration setting <varname>system-features</varname>.</para>
<para>By default, <varname>system-features</varname> includes
<literal>kvm</literal> if <filename>/dev/kvm</filename>
exists. For compatibility, it also includes the pseudo-features
<literal>nixos-test</literal>, <literal>benchmark</literal> and
<literal>big-parallel</literal> which are used by Nixpkgs to route
builds to particular Hydra build machines.</para>
</listitem>
<listitem>
<para>Sandbox builds are now enabled by default on Linux.</para>
</listitem>
<listitem>
<para>The new command <command>nix doctor</command> shows
potential issues with your Nix installation.</para>
</listitem>
<listitem>
<para>The <literal>fetchGit</literal> builtin function now uses a
caching scheme that puts different remote repositories in distinct
local repositories, rather than a single shared repository. This
may require more disk space but is faster.</para>
</listitem>
<listitem>
<para>The <literal>dirOf</literal> builtin function now works on
relative paths.</para>
</listitem>
<listitem>
<para>Nix now supports <link
xlink:href="https://www.w3.org/TR/SRI/">SRI hashes</link>,
allowing the hash algorithm and hash to be specified in a single
string. For example, you can write:
<programlisting>
import &lt;nix/fetchurl.nix> {
url = https://nixos.org/releases/nix/nix-2.1.3/nix-2.1.3.tar.xz;
hash = "sha256-XSLa0FjVyADWWhFfkZ2iKTjFDda6mMXjoYMXLRSYQKQ=";
};
</programlisting>
instead of
<programlisting>
import &lt;nix/fetchurl.nix> {
url = https://nixos.org/releases/nix/nix-2.1.3/nix-2.1.3.tar.xz;
sha256 = "5d22dad058d5c800d65a115f919da22938c50dd6ba98c5e3a183172d149840a4";
};
</programlisting>
</para>
<para>In fixed-output derivations, the
<varname>outputHashAlgo</varname> attribute is no longer mandatory
if <varname>outputHash</varname> specifies the hash.</para>
<para><command>nix hash-file</command> and <command>nix
hash-path</command> now print hashes in SRI format by
default. They also use SHA-256 by default instead of SHA-512
because that's what we use most of the time in Nixpkgs.</para>
</listitem>
<listitem>
<para>Integers are now 64 bits on all platforms.</para>
</listitem>
<listitem>
<para>The evaluator now prints profiling statistics (enabled via
the <envar>NIX_SHOW_STATS</envar> and
<envar>NIX_COUNT_CALLS</envar> environment variables) in JSON
format.</para>
</listitem>
<listitem>
<para>The option <option>--xml</option> in <command>nix-store
--query</command> has been removed. Instead, there now is an
option <option>--graphml</option> to output the dependency graph
in GraphML format.</para>
</listitem>
<listitem>
<para>All <filename>nix-*</filename> commands are now symlinks to
<filename>nix</filename>. This saves a bit of disk space.</para>
</listitem>
<listitem>
<para><command>nix repl</command> now uses
<literal>libeditline</literal> or
<literal>libreadline</literal>.</para>
</listitem>
</itemizedlist>
</section>