Docker Union Mount Volume Plugin

This is a docker plugin that facilitates creating union mounts as docker volumes by taking advantage of docker's graph driver. It's mostly useful in testing/staging/review areas where having the latest production data and being able to manipulate it, in a carefree manner, is necessary to test features and migrations.

Supported filesystems are:

AUFS
Overlay

Installation

Using go get:

$ go get -u http://github.com/Fardinak/docker-volume-unionmount

Usage

Run the daemon
```
$ docker-volume-unionmount
```
Available arguments:
- -root is the root directory for union mount driver's operations and volumes (defaults to /var/lib/docker-volumes/_unionmount/)
- -defaultfs is the default filesystem for this driver's volumes (defaults to docker's storage driver or aufs)
Create a named volume with the driver
```
$ docker volume create --driver unionmount -o layers=/path/to/newer/clone:/var/lib/postgresql/data pgsandbox_data
```
Available options:
- layers absolute path to layers of the union, from top to bottom, separated by colons :. The upper layer will be automatically generated by the driver. (Required)
- filesystem is the filesystem for this volume (defaults to driver's -defaultfs option)

Use the volume in one or more containers

$ docker run -it --rm -v pgsandbox_data:/var/lib/postgresql/data postgres:latest psql

TODOs

Filesystems as separate drivers (perhpase use docker's own graphdriver library)
Support multilayer with Overlay
Support Overlay2
Logging (logrus) and Debugging mode

Also: Review mounting other named volumes as layers to a union

License

Docker Union Mount Volume Plugin is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.