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

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Add hashed-mirrors back
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Eelco Dolstra 2020-08-14 17:05:47 +02:00 committed by GitHub
parent d81f13f7cb 96c158d6e1
commit 9b9d5297ba
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27
doc/manual/command-ref/conf-file.xml
View file

@ -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

14
src/libstore/builtins/fetchurl.cc
View file

@ -58,6 +58,20 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
}
};
/* Try the hashed mirrors first. */
if (getAttr("outputHashMode") == "flat")
for (auto hashedMirror : settings.hashedMirrors.get())
try {
if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
std::optional<HashType> ht = parseHashTypeOpt(getAttr("outputHashAlgo"));
Hash h = newHashAllowEmpty(getAttr("outputHash"), ht);
fetch(hashedMirror + printHashType(h.type) + "/" + h.to_string(Base16, false));
return;
} catch (Error & e) {
debug(e.what());
}
/* Otherwise try the specified URL. */
fetch(mainUrl);
}

3
src/libstore/globals.hh
View file

@ -335,6 +335,9 @@ public:
"setuid/setgid bits or with file capabilities."};
#endif
Setting<Strings> hashedMirrors{this, {}, "hashed-mirrors",
"A list of servers used by builtins.fetchurl to fetch files by hash."};
Setting<uint64_t> minFree{this, 0, "min-free",
"Automatically run the garbage collector when free disk space drops below the specified amount."};