Charm Layer for Storage

This repository contains the charm layer for storage, which can be used as a base layer for other charms that use the Juju storage feature. For more information about Juju charms or layers please refer to the Charm Layers documentation.

Usage

In a layer that wants to use storage, the integration can be as simple as placing the following in the layer.yaml file:

includes: ['layer:storage']

Then amend the reactive code as you require to deliver and manage the lifecycle of your applications using storage. Refer to the documentation on how to write a layer.

Once you have the code written to manage storage you need to assemble the charm from the layers. To do this run the charm build command from the layer directory you just created.

charm build

Once built you should be able to deploy the assembled charm.

juju deploy ./<series>/<charm-name>

Where series it the code name for Ubuntu releases, such as "trusty" or "xenial" and charm-name is what you named the layer in metadata.yaml.

States

The storage layer raises a few synthetic events:

• disk-pool-storage-attached

• disk-pool-storage-tools-installed

disk-pool-storage-attached

When the -storage-attached hook runs this layer emits the disk-pool-storage-attached event. Other layers could use this state to run operations after storage is attached, such as format, or create a file system.

@when('disk-pool-storage-attached')
def prepare_disk():
    # Do some checks and prepare the storage.

disk-pool-storage-tools-installed

When the disk-pool-storage-tools-installed state is emitted the appropriate tools for the pool have been installed.

@when('disk-pool-storage-tools-installed')
def storage_info():
    # Use the pool tools to get details about storage

Layer Options

storage-driver

The storage driver to use when mounting or pooling the devices. The supported pool types are btrfs, and zfs. The overlay and aufs drivers are also supported, but multiple devices will be mounted separately.