Merge pull request #3909 from matthewbauer/readd-hashed-mirrors

Add hashed-mirrors back

1 files changed, 27 insertions, 0 deletions

diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml
index 9c55526a3..d0f1b09ca 100644
--- a/doc/manual/command-ref/conf-file.xml
+++ b/doc/manual/command-ref/conf-file.xml
@@ -370,6 +370,33 @@ false</literal>.</para>
 
   </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