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name: cinder-volume/openstack-hypervisor
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description:
- The Cinder Volume snap contains the Volume handler from the OpenStack cinder service. This service is responsible for spawning volumes from external backends, such as Ceph, PureStorage, Hitachi, Dell SC…
- The OpenStack-Hypervisor snap contains the compute bits (mainly Libvirtd and Nova-Compute) which both needs access to these permissions to be able to mount and use the volumes prepared by Cinder Volume snap.
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snapcraft:
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upstream:
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upstream-relation: Cinder Volume snap and OpenStack Hypervisor are managed by the Canonical OpenStack team. We are a downstream distribution of the OpenStack project. This work is a part of the upstream Sunbeam work.
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interfaces:
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iscsi-initiator:
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request-type: auto-connection
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reasoning: Required to access iSCSI configuration files (/etc/iscsi/initiatorname.iscsi, /etc/iscsi/iscsid.conf) and establishing iSCSI connections to storage backends like PureStorage, Hitachi, and Dell SC arrays. Many enterprise storage systems use iSCSI as the primary protocol for volume attachment.
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nvme-control:
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request-type:auto-connection
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reasoning: Required to read NVMe host identification files (/etc/nvme/hostnqn, /etc/nvme/hostid) which are required for NVMe-over-TCP connections to modern storage arrays. Enterprise storage backends increasingly support NVMe protocols for high-performance volume access.
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dm-multipath:
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request-type: auto-connection
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reasoning: Required to allow mounting iscsi (or other kind of block devices) into a multipath setup for increased IO-performance and reliability. This is a common setup for production environment connecting to backends.
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Opening as a single requests for these two snaps as granting this only makes sense when both these snaps have access.
The role of cinder-volume is uniquely to communicate with the storage array, eventually mounting the image locally if an OS image needs to be burned on the volume or the volume needs to be cleaned up. All these means the cinder-volume snap needs the permissions to mount the remote volume locally and perform IO operations on it.
The role of the openstack-hypervisor is to mount locally these volume and attach them to the instances, allowing these instances to be based of remote storage for either increased performance or reliability.