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

1. 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)

2. 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)

3. 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.