問題

Mac上でdocker-machineでVMを立て、そこに向けてdocker-composeを華麗に決める

% docker-compose build
# 略
Step 5 : RUN bundle install
 ---> Running in e8c4e026277a
# 略
Fetching source index from https://rubygems.org/
Could not fetch specs from https://rubygems.org/
ERROR: Service 'hisyotan' failed to build: The command '/bin/sh -c bundle install' returned a non-zero code: 17

調査

qiita.com

これが似てる

解決

% docker-machine restart oppai

したら治った