Prefer downloading from mirrors

default.nix

@@ -4,18 +4,30 @@
 }: let
   inherit (pkgs) lib;
   sources = builtins.fromJSON (lib.strings.fileContents ./sources.json);
+  mirrors = builtins.fromJSON (lib.strings.fileContents ./mirrors.json);
 
   # mkBinaryInstall makes a derivation that installs Zig from a binary.
   mkBinaryInstall = {
     url,
     version,
     sha256,
-  }:
+  }: let
+    tarballName = lib.lists.last (lib.strings.split "/" url);
+    srcIsFromZigLang = lib.strings.hasPrefix "https://ziglang.org/" url;
+    urlFromMirrors =
+      builtins.map
+      (mirror: "${mirror}/${tarballName}?source=nix-zig-overlay")
+      mirrors;
+    urls =
+      if srcIsFromZigLang
+      then urlFromMirrors ++ [url]
+      else [url];
+  in
     pkgs.stdenv.mkDerivation {
       inherit version;
 
       pname = "zig";
-      src = pkgs.fetchurl {inherit url sha256;};
+      src = pkgs.fetchurl {inherit urls sha256;};
       dontConfigure = true;
       dontBuild = true;
       dontFixup = true;

mirrors.json

@@ -0,0 +1,9 @@
+[
+  "https://pkg.machengine.org/zig",
+  "https://zigmirror.hryx.net/zig",
+  "https://zig.linus.dev/zig",
+  "https://zig.squirl.dev",
+  "https://zig.florent.dev",
+  "https://zig.mirror.mschae23.de/zig",
+  "https://zigmirror.meox.dev"
+]

update

@@ -2,6 +2,8 @@
 #! nix-shell -p curl jq minisign -i sh
 set -e
 
+curl -s 'https://ziglang.org/download/community-mirrors.txt' | jq -R '.' | jq -s . > mirrors.json
+
 # The well known public key for Zig
 PUBLIC_KEY="RWSGOq2NVecA2UPNdBUZykf1CCb147pkmdtYxgb3Ti+JO/wCYvhbAb/U"