DockerBuilder: allow for remote Docker daemons

[nokome]

Currently, Dockter requires Docker to be installed on the system. That's because we're using:

const docker = new Docker() # Connects to local Docker daemon via '/var/run/docker.sock'

But, in theory, we could allow for a remote Docker daemon to build images (it would require that the folder contents be zipped up and send across the network). e.g.

const docker = new Docker({
  protocol: 'https',
  host: 'some.docker-server.org',
  port: process.env.DOCKER_PORT || 2375,
  ca: fs.readFileSync('ca.pem'),
  cert: fs.readFileSync('cert.pem'),
  key: fs.readFileSync('key.pem')
})

Not a high priority, but could be useful for users who don't have Docker installed and don't want to.

[giorgiosironi]

Remote docker is also a good option if you end up running the code inside another container, like in a Travis CI or Circle CI build. It has some limitations on running the image rather than on building it though, as it's difficult to mount local paths as volumes for the running containers to e.g. pass in data files or retrieve some generated ones.

[nokome]

@giorgiosironi : I was thinking it could be a useful option for researchers who don't want to install Docker on their machines. But yes, as you say there are issues when it comes to running containers remotely.