Merge pull request #3255 from Profpatsch/doc-manual-allowSubstitutes-add-note

doc/manual: add note to `allowSubstitutes` advanced attribute
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Eelco Dolstra 2019-12-04 12:46:31 +01:00 committed by GitHub
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@ -11,7 +11,7 @@ attributes.</para>
<variablelist>
<varlistentry><term><varname>allowedReferences</varname></term>
<varlistentry xml:id="adv-attr-allowedReferences"><term><varname>allowedReferences</varname></term>
<listitem><para>The optional attribute
<varname>allowedReferences</varname> specifies a list of legal
@ -32,7 +32,7 @@ allowedReferences = [];
</varlistentry>
<varlistentry><term><varname>allowedRequisites</varname></term>
<varlistentry xml:id="adv-attr-allowedRequisites"><term><varname>allowedRequisites</varname></term>
<listitem><para>This attribute is similar to
<varname>allowedReferences</varname>, but it specifies the legal
@ -50,7 +50,7 @@ allowedRequisites = [ foobar ];
</varlistentry>
<varlistentry><term><varname>disallowedReferences</varname></term>
<varlistentry xml:id="adv-attr-disallowedReferences"><term><varname>disallowedReferences</varname></term>
<listitem><para>The optional attribute
<varname>disallowedReferences</varname> specifies a list of illegal
@ -67,7 +67,7 @@ disallowedReferences = [ foo ];
</varlistentry>
<varlistentry><term><varname>disallowedRequisites</varname></term>
<varlistentry xml:id="adv-attr-disallowedRequisites"><term><varname>disallowedRequisites</varname></term>
<listitem><para>This attribute is similar to
<varname>disallowedReferences</varname>, but it specifies illegal
@ -85,7 +85,7 @@ disallowedRequisites = [ foobar ];
</varlistentry>
<varlistentry><term><varname>exportReferencesGraph</varname></term>
<varlistentry xml:id="adv-attr-exportReferencesGraph"><term><varname>exportReferencesGraph</varname></term>
<listitem><para>This attribute allows builders access to the
references graph of their inputs. The attribute is a list of
@ -124,7 +124,7 @@ derivation {
</varlistentry>
<varlistentry><term><varname>impureEnvVars</varname></term>
<varlistentry xml:id="adv-attr-impureEnvVars"><term><varname>impureEnvVars</varname></term>
<listitem><para>This attribute allows you to specify a list of
environment variables that should be passed from the environment
@ -158,9 +158,9 @@ impureEnvVars = [ "http_proxy" "https_proxy" <replaceable>...</replaceable> ];
<varlistentry xml:id="fixed-output-drvs">
<term><varname>outputHash</varname></term>
<term><varname>outputHashAlgo</varname></term>
<term><varname>outputHashMode</varname></term>
<term xml:id="adv-attr-outputHash"><varname>outputHash</varname></term>
<term xml:id="adv-attr-outputHashAlgo"><varname>outputHashAlgo</varname></term>
<term xml:id="adv-attr-outputHashMode"><varname>outputHashMode</varname></term>
<listitem><para>These attributes declare that the derivation is a
so-called <emphasis>fixed-output derivation</emphasis>, which
@ -282,7 +282,7 @@ stdenv.mkDerivation {
</varlistentry>
<varlistentry><term><varname>passAsFile</varname></term>
<varlistentry xml:id="adv-attr-passAsFile"><term><varname>passAsFile</varname></term>
<listitem><para>A list of names of attributes that should be
passed via files rather than environment variables. For example,
@ -309,7 +309,7 @@ big = "a very long string";
</varlistentry>
<varlistentry><term><varname>preferLocalBuild</varname></term>
<varlistentry xml:id="adv-attr-preferLocalBuild"><term><varname>preferLocalBuild</varname></term>
<listitem><para>If this attribute is set to
<literal>true</literal> and <link
@ -323,14 +323,25 @@ big = "a very long string";
</varlistentry>
<varlistentry><term><varname>allowSubstitutes</varname></term>
<varlistentry xml:id="adv-attr-allowSubstitutes"><term><varname>allowSubstitutes</varname></term>
<listitem><para>If this attribute is set to
<listitem>
<para>If this attribute is set to
<literal>false</literal>, then Nix will always build this
derivation; it will not try to substitute its outputs. This is
useful for very trivial derivations (such as
<function>writeText</function> in Nixpkgs) that are cheaper to
build than to substitute from a binary cache.</para></listitem>
build than to substitute from a binary cache.</para>
<note><para>You need to have a builder configured which satisfies
the derivations <literal>system</literal> attribute, since the
derivation cannot be substituted. Thus it is usually a good idea
to align <literal>system</literal> with
<literal>builtins.currentSystem</literal> when setting
<literal>allowSubstitutes</literal> to <literal>false</literal>.
For most trivial derivations this should be the case.
</para></note>
</listitem>
</varlistentry>