Docker optimisation & gem 'net-http-persistent'
I just tried to work with a smaller local copy of the docker images. In the end I:
- Re-organized the 'RUN' to decrease the number of layer (and the size, e.g. yum clean all)
- Use 'COPY' instead of run clone (allow to have difference in the other code, e.g. Gemfile)
- Compile the dockerfile from / instead of /ci/ (due to COPY)
- Use gem 'net-http-persistent', '2.9.4', because 3.0 is not compative