docker-unison

A Unison Docker container for fast file synchronization, i.e. on OSX where both VirtualBox shares as well as NFS is awfully slow.

Requirements

The only requirement is unison. It can be installed from your favorite package manager such as apt or brew.

Usage

With pure Docker (and, in this case, dlite):

$ UNISON=(docker run -d -p 5000:5000 jumoel/unison)
$ unison . socket://local.docker:5000/ -auto -batch
$ docker run --rm --volumes-from=$UNISON busybox ls -l /app

The -auto option for unison makes it run almost automatically and -batch makes it run without waiting for user input. See unison -help for more options.

Usage with docker-compose is similarly simple:

version: "2"
services:
  consumer:
    image: busybox
    command: sh -c "sleep 5 && ls -l /app"
    volumes_from:
      - unison
  unison:
    image: jumoel/unison
    ports:
      - "5000:5000"

To test it, run:

$ docker-compose up

In a new terminal, then hurry up and run

$ unison . socket://local.docker:5000/ -auto -batch

The sleep 5 && ls -l /app allows for time to synchronize the unison folder before listing the contents of it. In a real scenario, the unison service will probably need to be started separately, so an initial synchronization can be run before the consumer service needs the files.

Configuration

The container by default synchronizes to and shares the /app folder, but that can be configured with the UNISON_WORKING_DIR environment variable.

Unison is set up as ENTRYPOINT, so additional parameters when running the container will be passed on to the program.