common-updater: support for github updates

pkgs/common-updater/scripts.nix

@@ -1,4 +1,4 @@
-{ stdenv, makeWrapper, coreutils, gawk, gnused, diffutils, nix }:
+{ stdenv, makeWrapper, coreutils, gawk, gnused, diffutils, nix, curl, jq }:
 
 stdenv.mkDerivation {
   name = "common-updater-scripts";
@@ -12,7 +12,7 @@ stdenv.mkDerivation {
     cp ${./scripts}/* $out/bin
 
     for f in $out/bin/*; do
-      wrapProgram $f --prefix PATH : ${stdenv.lib.makeBinPath [ coreutils gawk gnused nix diffutils ]}
+      wrapProgram $f --prefix PATH : ${stdenv.lib.makeBinPath [ coreutils gawk gnused nix diffutils curl jq ]}
     done
   '';
 }

pkgs/common-updater/scripts/update-source-version

@@ -1,12 +1,12 @@
 #!/usr/bin/env bash
-set -e
+set -e -o pipefail
 
 die() {
     echo "$0: error: $1" >&2
     exit 1
 }
 
-# Usage: update-source-hash <attr> <version> [<new-source-hash>]
+# Usage: update-source-hash <attr> [<version>] [<new-source-hash>]
 attr=$1
 newVersion=$2
 newHash=$3
@@ -34,6 +34,20 @@ if [ -z "$drvName" -o -z "$oldVersion" ]; then
     die "Couldn't evaluate name and version from '$attr.name'!"
 fi
 
+if [ -z "$newVersion" ]; then
+   # works for fetchFromGitHub & fetchgit
+   url=$(nix-instantiate --eval --strict --expr "with import ./. {}; if $attr ? src.meta.homepage then $attr.src.meta.homepage else $attr.src.url")
+   if [[ -z "$url" ]] || ! [[ "$url" =~ \"https://github.com/([^\)]+)/([^\)/]+)\" ]]; then
+       die "we can only automatically check for new versions for github-based projects, got '$url'"
+   fi
+   owner=${BASH_REMATCH[1]}
+   repo=${BASH_REMATCH[2]%.git}
+   newVersion=$(curl -s "https://api.github.com/repos/${owner}/${repo}/tags" | jq -r '.[0]?.name | gsub("^v"; "")')
+   if [[ $newVersion == "" ]]; then
+       die "no tags found for $url"
+   fi
+fi
+
 if [ "$oldVersion" = "$newVersion" ]; then
     echo "$0: New version same as old version, nothing to do." >&2
     exit 0