Overview

This charm provides the swift-proxy component of the OpenStack Swift object storage system. It can be deployed as part of its own stand-alone storage cluster or it can be integrated with the other OpenStack components, assuming those are also managed by Juju. For Swift to function, you'll also need to deploy additional swift-storage nodes using the cs:precise/swift-storage charm.

For more information about Swift and its architecture, visit the official project website

This charm was developed to support deploying multiple version of Swift on Ubuntu Precise 12.04, as they relate to the release series of OpenStack. That is, OpenStack Essex corresponds to Swift 1.4.8 while OpenStack Folsom shipped 1.7.4. This charm can be used to deploy either (and future) versions of Swift onto an Ubuntu Precise 12.04, making use of the Ubuntu Cloud Archive when needed.

Usage

Currently, Swift may be deployed in two ways. In either case, additional storage nodes are required. The configuration option that dictates how to deploy this charm is the 'zone-assignment' setting. This section describes how to select the appropriate zone assignment policy, as well as a few other configuration settings of interest. Many of the configuration settings can be left as default.

Zone Assignment

This setting determines how the charm assigns new storage nodes to storage zones.

The default, 'manual' option is suggested for production as it allows administrators to carefully architect the storage cluster. It requires each swift-storage service to be deployed with an explicit storage zone configured in its deployment settings. Upon relation to a swift-proxy, the storage node will request membership to its configured zone and be assigned by the swift-proxy charm accordingly. Using the cs:precise/swift-storage charm with this charm, a deployment would look something like:

$ cat >swift.cfg <<END
    swift-proxy:
        zone-assignment: manual
        replicas: 3
    swift-storage-zone1:
        zone: 1
        block-device: sdb
    swift-storage-zone2:
        zone: 2
        block-device: sdb
    swift-storage-zone3:
        zone: 3
        block-device: sdb
END
$ juju deploy --config=swift.cfg swift-proxy
$ juju deploy --config=swift.cfg swift-storage swift-storage-zone1
$ juju deploy --config=swift.cfg swift-storage swift-storage-zone2
$ juju deploy --config=swift.cfg swift-storage swift-storage-zone3
$ juju add-relation swift-proxy swift-storage-zone1
$ juju add-relation swift-proxy swift-storage-zone2
$ juju add-relation swift-proxy swift-storage-zone3

This will result in a configured storage cluster of 3 zones, each with one node. To expand capacity of the storage system, nodes can be added to specific zones in the ring.

$ juju add-unit swift-storage-zone1
$ juju add-unit -n5 swift-storage-zone3    # Adds 5 units to zone3

This charm will not balance the storage ring until there are enough storage zones to meet its minimum replica requirement, in this case 3.

The other option for zone assignment is 'auto'. In this mode, swift-proxy gets a relation to a single swift-storage service unit. Each machine unit assigned to that service unit will be distributed evenly across zones.

$ cat >swift.cfg <<END
swift-proxy:
    zone-assignment: auto
    replicas: 3
swift-storage:
    zone: 1
    block-device: sdb
END
$ juju deploy --config=swift.cfg swift-proxy
$ juju deploy --config=swift.cfg swift-storage
$ juju add-relation swift-proxy swift-storage
# The swift-storage/0 unit ends up the first node in zone 1
$ juju add-unit swift-storage
# swift-storage/1 ends up the first node in zone 2.
$ juju add-unit swift-storage
# swift-storage/2 is the first in zone 3, replica requirement is satisfied
# the ring is balanced.

Extending the ring in the case is just a matter of adding more units to the single service unit. New units will be distributed across the existing zones.

$ juju add-unit swift-storage
# swift-storage/3 is assigned to zone 1.
$ juju add-unit swift-storage
# swift-storage/4 is assigned to zone 2.
etc.

Installation repository.

The 'openstack-origin' setting allows Swift to be installed from installation repositories and can be used to setup access to the Ubuntu Cloud Archive to support installing Swift versions more recent than what is shipped with Ubuntu 12.04 (1.4.8). For more information, see config.yaml.

Authentication.

By default, the charm will be deployed using the tempauth auth system. This is a simple and not-recommended auth system that functions without any external dependencies. See Swift documentation for details.

The charm may also be configured to use Keystone, either manually (via config) or automatically via a relation to an existing Keystone service using the cs:precise/keystone charm. The latter is preferred, however, if a Keystone service is desired but it is not managed by Juju, the configuration for the auth token middleware can be set manually via the charm's config. A relation to a Keystone server via the identity-service interface will configure swift-proxy with the appropriate credentials to make use of Keystone and is required for any integration with other OpenStack components.

Glance

Swift may be used to as a storage backend for the Glance image service. To do so, simply add a relation between swift-proxy and an existing Glance service deployed using the cs:precise/glance charm.