Merge pull request #9545 from p8/rack/iodine-set-workers2

[ruby/rack] Detect workers for Iodine

frameworks/Ruby/rack/rack-iodine.dockerfile

@@ -19,4 +19,4 @@ COPY . .
 
 EXPOSE 8080
 
-CMD bundle exec iodine -p 8080
+CMD bundle exec iodine -p 8080 -w $(ruby config/auto_tune.rb | grep -Eo '[0-9]+' | head -n 1)