Review and improve README
The dubious 'guess' method for block-device determination was removed. It remains in config.yaml. This PR should be reviewed alongside the nearby PR for the swift-proxy README. Change-Id: I2a0fa8491fc61ef362db4fc25e66c069abfb03f6
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Peter Matulis
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README.md
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README.md
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Overview
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--------
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# Overview
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This charm provides the swift-storage component of the OpenStack Swift object
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storage system. It can be deployed as part of its own standalone storage
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cluster or it can be integrated with the other OpenStack components, assuming
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those are also managed by Juju. For Swift to function, you'll also need to
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deploy an additional swift-proxy using the cs:precise/swift-proxy charm.
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OpenStack [Swift][swift-upstream] is a highly available, distributed,
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eventually consistent object/blob store.
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For more information about Swift and its architecture, visit the official
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[Swift project website][swift-project].
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The swift-storage charm deploys Swift's storage component. The charm's basic
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function is to initialise storage devices and manage the container, object, and
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account services. It works in tandem with the [swift-proxy][swift-proxy-charm]
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charm, which is used to add proxy nodes.
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This charm is intended to track each LTS release of Ubuntu Server, as well as
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newer OpenStack releases via the Ubuntu Cloud Archive as supported by each
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Ubuntu LTS version. Non-LTS (interim release) Ubuntu server versions are
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enabled in the charms strictly for development and testing purposes.
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# Usage
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Usage
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-----
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## Configuration
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This charm is quite simple. Its basic function is to get a storage device
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setup for swift usage, and run the container, object and account services.
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The deployment workflow for swift using this charm is covered in the README
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for the swift-proxy charm at cs:precise/swift-proxy. The following are
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deployment options to take into consideration when deploying swift-storage.
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This section covers common configuration options. See file `config.yaml` for
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the full list of options, along with their descriptions and default values.
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**Zone assignment**
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### `zone`
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If the swift-proxy charm is configured for manual zone assignment (recommended),
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the 'zone' option should be set for each swift-storage service being deployed.
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See the swift-proxy README for more information about zone assignment.
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The `zone` option assigns a storage zone (an integer) to a storage node. A zone
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is associated with data replicas.
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**Region assignment**
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### `block-device`
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If the swift-proxy charm is configured with the Swift Global Cluster feature,
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the 'region' option should be set for each swift-storage service being deployed.
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See the [swift-proxy charm README][swift-proxy-charm-readme] for more information
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about the Swift Global Cluster feature.
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The `block-device` option specifies the device(s) that will be used on all
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machines associated with the application. Value types include:
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**Storage**
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* an actual block device (e.g. 'sdb' or '/dev/sdb'). A space-separated list is
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used for multiple devices.
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* a path to a local file with the size appended after a pipe (e.g.
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'/etc/swift/storagedev1.img|5G'). The file will be created if necessary and
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be mapped to a loopback device. This is intended for development and testing
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purposes.
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Swift storage nodes require access to local storage and filesystem. The charm
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takes a 'block-device' config setting that can be used to specify which storage
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device(s) to use. Options include:
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The resulting block device(s) will be XFS-formatted and use
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`/srv/node/<device-name>` as a mount point.
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- 1 or more local block devices (eg, sdb or /dev/sdb). It's important that this
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device be the same on all machine units assigned to this service. Multiple
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block devices should be listed as a space-separated list of device nodes.
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- a path to a local file on the filesystem with the size appended after a pipe,
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eg "/etc/swift/storagedev1.img|5G". This will be created if it does not
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exist and be mapped to a loopback device. Intended strictly for development
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and testing.
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- "guess" can be used to tell the charm to do its best to find a local devices
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to use. *EXPERIMENTAL*
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### `storage-region`
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Multiple devices can be specified. In all cases, the resulting block device(s)
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will each be formatted as XFS file system and mounted at /srv/node/$devname.
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The `storage-region` option specifies a storage region (an integer). It is used
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only for multi-region (global) clusters.
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**Installation repository**
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## Deployment
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The 'openstack-origin' setting allows Swift to be installed from repositories
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such as the Ubuntu Cloud Archive, which enables installation of Swift versions
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more recent than what shipped with the Ubuntu LTS release. For more
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information, see config.yaml.
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Let file ``swift.yaml`` contain the deployment configuration:
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```yaml
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swift-proxy:
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zone-assignment: manual
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replicas: 3
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swift-storage-zone1:
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zone: 1
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block-device: /dev/sdb
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swift-storage-zone2:
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zone: 2
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block-device: /dev/sdb
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swift-storage-zone3:
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zone: 3
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block-device: /dev/sdb
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```
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Deploy the proxy and storage nodes:
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juju deploy --config swift.yaml swift-proxy
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juju deploy --config swift.yaml swift-storage swift-storage-zone1
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juju deploy --config swift.yaml swift-storage swift-storage-zone2
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juju deploy --config swift.yaml swift-storage swift-storage-zone3
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Add relations between the proxy node and all storage nodes:
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juju add-relation swift-proxy:swift-storage swift-storage-zone1:swift-storage
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juju add-relation swift-proxy:swift-storage swift-storage-zone2:swift-storage
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juju add-relation swift-proxy:swift-storage swift-storage-zone3:swift-storage
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This will result in a three-zone cluster, with each zone consisting of a single
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storage node, thereby satisfying the replica requirement of three.
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Storage capacity is increased by adding swift-storage units to a zone. For
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example, to add two storage nodes to zone '3':
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juju add-unit -n 2 swift-storage-zone3
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> **Note**: When scaling out ensure the candidate machines are equipped with
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the block devices currently configured for the associated application.
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This charm will not balance the storage ring until there are enough storage
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zones to meet its minimum replica requirement, in this case three.
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Appendix [Swift usage][cdg-app-swift] in the [OpenStack Charms Deployment
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Guide][cdg] offers in-depth guidance for deploying Swift with charms. In
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particular, it shows how to set up a multi-region (global) cluster.
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## Actions
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This section covers Juju [actions][juju-docs-actions] supported by the charm.
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Actions allow specific operations to be performed on a per-unit basis.
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* `openstack-upgrade`
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* `pause`
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* `resume`
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To display action descriptions run `juju actions swift-storage`.
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# Bugs
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Please report bugs on [Launchpad][lp-bugs-charm-swift-storage].
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For general charm questions refer to the [OpenStack Charm Guide][cg].
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<!-- LINKS -->
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[cg]: https://docs.openstack.org/charm-guide
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[cdg]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide
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[cdg-app-swift]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-swift.html
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[swift-proxy-charm]: https://jaas.ai/swift-proxy
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[swift-proxy-charm-readme]: https://opendev.org/openstack/charm-swift-proxy/src/branch/master/README.md
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[swift-project]: https://docs.openstack.org/developer/swift
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[swift-upstream]: https://docs.openstack.org/developer/swift
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[lp-bugs-charm-swift-storage]: https://bugs.launchpad.net/charm-swift-storage/+filebug
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[juju-docs-actions]: https://jaas.ai/docs/actions
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