rubygems: Fetch versions file from upstream

rubygems/Dockerfile

@@ -1,6 +1,6 @@
 FROM ustcmirror/base:alpine
 LABEL maintainer="Yifan Gao <[email protected]>"
-ENV UPSTREAM=http://rubygems.org
+ENV UPSTREAM=https://rubygems.org
 RUN apk add --no-cache ruby ca-certificates && \
     gem install --no-document rubygems-mirror
 ADD sync.sh pre-sync.sh /

rubygems/sync.sh

@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -x
+
 export HOME=/root
 cat << EOF > /root/.gem/.mirrorrc
 ---
@@ -10,4 +12,11 @@ cat << EOF > /root/.gem/.mirrorrc
   delete: false
   skiperror: true
 EOF
+
+# Fetch index
+wget -qO "$TO/versions.new" "$UPSTREAM/versions"
+md5sum "$TO/versions.new" > "$TO/versions.md5sum.new"
+mv -f "$TO/versions.new" "$TO/versions"
+mv -f "$TO/versions.md5sum.new" "$TO/versions.md5sum"
+
 exec gem mirror