Failed to build 

I am using Ubuntu 16.04 x64 and I have installed docker as well as gem. But it refuses to build successfully when I ran `docker-compose build && docker-compose up -d` in the directory. 
<img width="779" alt="untitled" src="https://user-images.githubusercontent.com/22718011/37166383-bfd11f1c-22b3-11e8-9ac5-a77e7880fa4b.png">
