nixpkgs-update: add fetch-repology script

hosts/build02/nixpkgs-update.nix

@@ -109,6 +109,14 @@ let
     startAt = "0/12:10"; # every 12 hours
   };
 
+  repology = pkgs.writeShellApplication {
+    name = "repology";
+    runtimeInputs = [
+      pkgs.jq
+      pkgs.moreutils
+    ];
+    text = builtins.readFile ./repology.bash;
+  };
 in
 {
   users.groups.r-ryantm = { };
@@ -147,10 +155,9 @@ in
     script = "${nixpkgs-update-bin} delete-done --delete";
   };
 
-  systemd.services.nixpkgs-update-fetch-repology = mkFetcher "repology" "${nixpkgs-update-bin} fetch-repology";
-
-  systemd.services.nixpkgs-update-fetch-updatescript = mkFetcher "updatescript" "${pkgs.nix}/bin/nix eval --option max-call-depth 100000 --raw -f ${./packages-with-update-script.nix}";
   systemd.services.nixpkgs-update-fetch-github = mkFetcher "github" "${inputs.nixpkgs-update-github-releases}/main.py";
+  systemd.services.nixpkgs-update-fetch-repology = mkFetcher "repology" (lib.getExe repology);
+  systemd.services.nixpkgs-update-fetch-updatescript = mkFetcher "updatescript" "${pkgs.nix}/bin/nix eval --option max-call-depth 100000 --raw -f ${./packages-with-update-script.nix}";
 
   systemd.services.nixpkgs-update-worker1 = mkWorker "worker1";
   systemd.services.nixpkgs-update-worker2 = mkWorker "worker2";

hosts/build02/repology.bash

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+file=$(mktemp)
+>&2 echo "$file"
+
+fetch() {
+  local url="$1"
+  >&2 echo "$url"
+  curl --silent --compressed --user-agent "https://github.com/nix-community/infra" --location "$url"
+}
+
+fetch "https://repology.org/api/v1/projects/?inrepo=nix_unstable&outdated=1" >"$file"
+
+append() {
+  sleep 2
+  local last="$1"
+  local url="https://repology.org/api/v1/projects/$last/?inrepo=nix_unstable&outdated=1"
+  fetch "$url" >>"$file"
+}
+
+while true; do
+  last=$(jq --sort-keys --raw-output 'keys | last' <"$file")
+
+  append "$last"
+
+  jq --slurp add "$file" | sponge "$file"
+
+  final=$(jq --sort-keys --raw-output 'keys | last' <"$file")
+  if [[ $last == "$final" ]]; then
+    break
+  fi
+done
+
+jq -r '
+  to_entries |
+  map(select(.value | type == "array")) |
+  map({
+    name: (
+      .value |
+      map(select(.repo == "nix_unstable")) |
+      .[0] |
+      .srcname
+    ),
+    oldVersion: (
+      .value |
+      map(select(.repo == "nix_unstable" and .status == "outdated")) |
+      .[0] |
+      .version
+    ),
+    newVersion: (
+      .value |
+      map(select(.status == "newest" and .version != null)) |
+      .[0] |
+      .version
+    ),
+    url: "https://repology.org/project/\(.key)/versions"
+  }) |
+  map(select(.newVersion != null)) |
+  map("\(.name) \(.oldVersion) \(.newVersion) \(.url)") |
+  join("\n")
+' <"$file" | sort