Mount host directory into bundle

[geowa4]

At work, we use CoreOS's Fleet to schedule our containers across a few servers. Interaction with Fleet is via a unix socket /var/run/fleet.sock. I would like to build a standard Docker bundle to list, start, and stop units. To do that, I'll need the Relay to send the mount option to the container. I imagine a slight change to the config.yaml as follows.

Current:

docker:
  image: my/bundle
  tag: "0.1"

Proposed:

docker:
  image: my/bundle
  volumes:
    - /path/on/host:/path/on/container
  tag: "0.1"

[christophermaier]

This is done and available now on the master branch of both Cog and Relay. It will be available in the next release of Cog.

To bind mounts into the container you can do something like this:

docker:
  image: my/bundle
  binds:
    - /path/on/host:/path/on/container
    - /another/host/path:/another/container/path
  tag: "0.1"

binds is a list of strings you would pass as values in HostConfig -> Binds in the POST body for the Docker /containers/create API endpoint

The relevant bit of that documentation for our purposes is quoted here:

host_path:container_path to bind-mount a host path into the container
host_path:container_path:ro to make the bind-mount read-only inside the container.
volume_name:container_path to bind-mount a volume managed by a volume plugin into the container.
volume_name:container_path:ro to make the bind mount read-only inside the container.