Support build --network

[cjbottaro]

docker build supports --network option (note, this is different from docker run's --net option).

Request extending docker-compose yaml spec to include the following:

build:
  context: .
  network: host

Thanks.

[czerasz]

This is a really useful feature. Specially for Ruby environments. With this option one can use Gemstash to cache the gems.

[ColinHebert]

Duplicate of #4095

[gustavosbarreto]

This is a really useful feature. Specially for Ruby environments. With this option one can use Gemstash to cache the gems.

Also for "RUN npm install --registry http://my-private-registry-inside-network" instruction with private npm registry.

+1

[eyz]

I would like this our environment as well. We have some services are that required during the build process, that should be linked to the building containers for abstraction.