Swift Backup Driver for Cinder¶

It is possible to use swift API for cinder backup purposes. In one of the configurations the swift API provider is deployed via non-Juju means. This spec is aimed to address this use-case specifically.

Problem Description¶

Cinder has support for backing up volumes via Swift API. In order to use it a URL is needed along with authentication details.

The following methods are supported to use to authenticate against a swift endpoint:

v2 auth (URL, username, password, tenant);
v3 auth (URL, username, password, project domain, project, user domain, username, password);

The backup to swift functionality is supported on all versions of OpenStack supported at the time of writing. It was added in 2013.1

Backup configuration should be added to cinder.conf and can be propagated from the cinder-backup-like charm to the cinder charm. Extending the existing cinder-backup charm is not favorable as it is ceph-specific.

Config options for the swift backend are present here

Proposed Change¶

Implement a new subordinate charm in reactive framework. This charm will be deployed alongside cinder deployments. This will be a subordinate charm to cinder, that installs cinder-backup and configures cinder to use swift as a backend for volume backups.

config options for configuring the swift backend. Following configs need to be modeled in the charm.
- backup_swift_url
- backup_swift_auth_url
- backup_swift_user
- backup_swift_key
- backup_swift_auth_version
- backup_swift_tenant
- backup_swift_user_domain
- backup_swift_project_domain
- backup_swift_project
- backup_swift_container
- backup_swift_object_size
- backup_swift_block_size
- backup_swift_ca_cert_file

Implement a new interface cinder-backup in reactive framework for sending cinder-backup external backend configuration.

Alternatives¶

extend cinder-backup to support swift options (discarded as it is already Ceph-specific);
extend cinder-backup to support clusters not deployed via charms by creating proxy charms (discarded as cinder-backup is Ceph-specific and proxy charms add additional complexity).

Implementation¶

Assignee(s)¶

Primary assignee:: yoshikadokawa alitvinov

Gerrit Topic¶

Use Gerrit topic “cinder-backend-swift” for all patches related to this spec.

git-review -t cinder-backend-swift

Work Items¶

Implement a new reactive subordinate charm, cinder-backup-swift
Implement a new reactive charm interface, cinder-backup
write unit tests;
write functional tests using the zaza test framework (a functional tests should include deploying swift via swift-proxy and swift-storage charms with config options used to connect to it from the cinder-backend-swift charm).

Repositories¶

The existing classic-style charm in the following repository:

openstack/charm-cinder-backup-swift

will be replaced by the new reactive charm.

New git repository:

openstack/charm-interface-cinder-backup

Documentation¶

The charm should contain documented options and authentication methods for the target Swift cluster.

Security¶

The Swift endpoint might be TLS-terminated, therefore, an option to provide a CA certificate is required.

Testing¶

unit tests;
functional tests (as mentioned above).

Dependencies¶

This charm will support OpenStack Queens and Ubuntu 18.04 Bionic as its baseline
A new project will need to be created based on the OpenStack Project Creator’s Guide

Swift Backup Driver for Cinder