mastodon: simplify update script

pkgs/servers/mastodon/default.nix

···
 
   passthru = {
     tests.mastodon = nixosTests.mastodon;
-    updateScript = callPackage ./update.nix {};
+    # run with: nix-shell ./maintainers/scripts/update.nix --argstr package mastodon
+    updateScript = ./update.sh;
   };
 
   meta = with lib; {

pkgs/servers/mastodon/update.nix

···
-{ runCommand
-, lib
-, makeWrapper
-, yarn2nix
-, bundix
-, coreutils
-, diffutils
-, nix-prefetch-github
-, gnused
-, jq
-}:
-let
-  binPath = lib.makeBinPath [ yarn2nix bundix coreutils diffutils nix-prefetch-github gnused jq ];
-in
-runCommand "mastodon-update-script"
-{
-  nativeBuildInputs = [ makeWrapper ];
-
-  meta = {
-    maintainers = with lib.maintainers; [ happy-river ];
-    description = "Utility to generate Nix expressions for Mastodon's dependencies";
-    platforms = lib.platforms.unix;
-  };
-} ''
-  mkdir -p $out/bin
-  cp ${./update.sh} $out/bin/update.sh
-  patchShebangs $out/bin/update.sh
-  wrapProgram $out/bin/update.sh --prefix PATH : ${binPath}
-''

pkgs/servers/mastodon/update.sh

···
-#!/usr/bin/env bash
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash -p yarn2nix bundix coreutils diffutils nix-prefetch-github gnused jq
 set -e
 
 OWNER=mastodon
···
     esac
 done
 
-if [[ -z "$VERSION" || -n "$POSITIONAL" ]]; then
-    echo "Usage: update.sh [--owner OWNER] [--repo REPO] --ver VERSION [--rev REVISION] [--patches PATCHES]"
-    echo "OWNER and repo must be paths on github."
-    echo "If VERSION is not a revision acceptable to 'git checkout', you must provide one in REVISION."
+if [[ -n "$POSITIONAL" ]]; then
+    echo "Usage: update.sh [--owner OWNER] [--repo REPO] [--ver VERSION] [--rev REVISION] [--patches PATCHES]"
+    echo "OWNER and REPO must be paths on github."
+    echo "If REVISION is not provided, the latest tag from github.com/mastodon/mastodon is fetched and VERSION is calculated from it."
     echo "If OWNER and REPO are not provided, it defaults they default to mastodon and mastodon."
     echo "PATCHES, if provided, should be one or more Nix expressions separated by spaces."
     exit 1
 fi
 
 if [[ -z "$REVISION" ]]; then
-    REVISION="$VERSION"
+    REVISION="$(curl ${GITHUB_TOKEN:+" -u \":$GITHUB_TOKEN\""} -s "https://api.github.com/repos/$OWNER/$REPO/releases" | jq -r  'map(select(.prerelease == false)) | .[0].tag_name')"
+    VERSION="$(echo "$REVISION" | cut -c2-)"
 fi
 
 rm -f gemset.nix version.nix source.nix
-TARGET_DIR="$PWD"
-
+cd "$(dirname "${BASH_SOURCE[0]}")" || exit 1
 
 WORK_DIR=$(mktemp -d)
 
···
 # This file was generated by pkgs.mastodon.updateScript.
 { fetchFromGitHub, applyPatches }: let
   src = fetchFromGitHub {
-    owner = "mastodon";
-    repo = "mastodon";
+    owner = "$OWNER";
+    repo = "$REPO";
     rev = "$REVISION";
     sha256 = "$SHA";
   };
···
 
 echo "Creating gemset.nix"
 bundix --lockfile="$SOURCE_DIR/Gemfile.lock" --gemfile="$SOURCE_DIR/Gemfile"
-echo "" >> "$TARGET_DIR/gemset.nix"  # Create trailing newline to please EditorConfig checks
+echo "" >> gemset.nix  # Create trailing newline to please EditorConfig checks