Docker::Compose::Session#run always requires a command

[bilby91]

docker-compose run service_name can be called without an explicit command. When no command is given, compose will use the command key in the docker-compose specification or default to the CMD in the Dockerfile definition if one was given at build time.

I think that command should be optional but based on how the api works right now, making the command optional will be a breaking change.

Thoughts @xeger ?

[xeger]

Are you sure this isn't supported right now? The method signature uses a position glob *cmd so in theory, it should be legal to pass 0 extra params to Session#run. (You'd still need to provide the service name, but not a command.)

 def run(service, *cmd, ...)

[xeger]

Verified that this (should be) supported; there's a unit test case for it:

    it 'runs containers' do
      expect(shell).to receive(:run).with('docker-compose', 'run', {}, 'service1', [])
      session.run('service1')
    end