ganeti-extstorage-csi

Ganeti support for CSI through external storage interface.

Architecture

+--------------------+     +-----------------------+     +------------+
|                    |     |                       |     |            |
|       Ganeti       +-----> ganeti-extstorage-csi +-----> csi-driver |
|                    |     |                       |     |            |
+--------------------+     +------------+----------+     +------------+
                                        |
                                        |
                                        |
                                        |
                              +---------v----------+
                              |                    |
                              |  Metadata storage  |
                              |                    |
                              +--------------------+

ganeti-extstorage-csi implements ganeti-extstorage-interface. It translates Ganeti operations to CSI operations, and stores returned metadata in Metadata storage. During requests, ganeti-extstorage-csi contacts Metadata storage.

Metadata storage

Upon volume creation, CSI returns data, which is stored in Metadata storage. This data should be accessible on all nodes. For this, an etcd cluster is recommended to be set up across all nodes.

For testing/development purposes, a simple file based metadata storage is available, which stores metadata in files. This is just for development, not for production.

TODO

• Make all operations as idempotent as possible.

Install

Running simply ganeti-extstorage-csi-install will install the extstorage provider named csi. If you want a different name, pass it via environment variable PROVIDER when running the install script. This will actually populate folder /usr/lib/ganeti-extstorage-csi/$PROVIDER and configuration file /etc/ganeti-extstorage-csi/$PROVIDER.env. Edit the latter to setup CSI endpoint, metadata storage.

Usage

When set up correctly, creating a ganeti instance with disk provided by this driver is simple, just run

# gnt-instance add -t ext --disk 0:size=10G,provider=<provider> ...

Set <provider> to the provider name (csi by default).

TrueNAS-CSI settings

A TrueNAS csi driver can handle multiple NAS and each NAS may have multiple configurations, see https://github.com/dravanet/truenas-csi/tree/master/examples. ganeti-extstorage-csi has support for selecting the desired configuration. These are available as extstorage parameters:

• truenas_csi_nas
• truenas_csi_config

They are optional, and can be passed as options:

# gnt-instance add -t ext --disk 0:size=10G,provider=<provider>,truenas_csi_nas=xxx,truenas_csi_config=yyy ...