Ruby stuff doesn't work

[Xe]

core@flitter ~ $ /usr/bin/docker run --rm -P --name app-rails-4ba97409 --hostname rails -e HOST=$COREOS_PRIVATE_IPV4 10.132.196.65:5000/xena/rails:4ba9740 /bin/bash -x /start web
+ export HOME=/app
+ HOME=/app
+ chown -R u23685:u23685 /app
+ cd /app
+ for file in '.profile.d/*.sh'
+ source .profile.d/00_config_vars.sh
++ export LANG=en_US.UTF-8
++ LANG=en_US.UTF-8
++ export RACK_ENV=production
++ RACK_ENV=production
+ for file in '.profile.d/*.sh'
+ source .profile.d/ruby.sh
++ export GEM_PATH=/app/vendor/bundle/ruby/2.1.0:/app/vendor/bundle/ruby/2.1.0:
++ GEM_PATH=/app/vendor/bundle/ruby/2.1.0:/app/vendor/bundle/ruby/2.1.0:
++ export LANG=en_US.UTF-8
++ LANG=en_US.UTF-8
++ export PATH=/app/bin:/app/vendor/bundle/bin:/app/vendor/bundle/ruby/2.1.0/bin:/app/bin:/app/vendor/bundle/bin:/app/vendor/bundle/ruby/2.1.0/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
++ PATH=/app/bin:/app/vendor/bundle/bin:/app/vendor/bundle/ruby/2.1.0/bin:/app/bin:/app/vendor/bundle/bin:/app/vendor/bundle/ruby/2.1.0/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
++ export RACK_ENV=production
++ RACK_ENV=production
+ hash -r
+ case "$(basename $0)" in
++ basename /start
+ [[ -f Procfile ]]
++ ruby -e 'require '\''yaml'\'';puts YAML.load_file('\''Procfile'\'')['\''web'\'']'
+ command='bundle exec ruby web.rb -p $PORT'
++ eval echo bundle exec ruby web.rb -p '$PORT'
+++ echo bundle exec ruby web.rb -p 8000
+ setuidgid u23685 bundle exec ruby web.rb -p 8000
setuidgid: fatal: unable to setgid: permission denied