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KEP-5943: Introducing Snapshot Topology #606

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KEP-5943: Introducing Snapshot Topology #606

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35 changes: 35 additions & 0 deletions csi.proto
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Original file line number Diff line number Diff line change
Expand Up @@ -237,6 +237,14 @@ message PluginCapability {
// The presence of this capability determines whether the CO will
// attempt to invoke the OPTIONAL SnapshotMetadata service RPCs.
SNAPSHOT_METADATA_SERVICE = 4 [(alpha_enum_value) = true];

// SNAPSHOT_ACCESSIBILITY_CONSTRAINTS indicates that the snapshots
// for this plugin MAY NOT be equally accessible from all
// topologies in the cluster. The CO MUST use the topology
// information returned in the CreateSnapshotResponse to ensure
// that a desired volume can be provisioned from a given snapshot
// when scheduling workloads.
SNAPSHOT_ACCESSIBILITY_CONSTRAINTS = 5 [(alpha_enum_value) = true];
}
Type type = 1;
}
Expand Down Expand Up @@ -1229,6 +1237,19 @@ message CreateSnapshotRequest {
// - Specify primary or secondary for replication systems that
// support snapshotting only on primary.
map<string, string> parameters = 4;

// Specifies where (regions, zones, racks, etc.) the provisioned
// snapshot MUST be accessible from.
// An SP SHALL advertise the requirements for topological
// accessibility information in documentation. COs SHALL only specify
// topological accessibility information supported by the SP.
// This field is OPTIONAL.
// This field SHALL NOT be specified unless the SP has the
// SNAPSHOT_ACCESSIBILITY_CONSTRAINTS plugin capability.
// If this field is not specified and the SP has the
// SNAPSHOT_ACCESSIBILITY_CONSTRAINTS plugin capability, the SP MAY
// choose where the provisioned snapshot is accessible from.
TopologyRequirement accessibility_requirements = 5 [(alpha_field) = true];

@gnufied gnufied Jul 1, 2026 •
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Why can't this be determined by SP from volume?

To be clear - I accept that we probably need the topology in CreateSnapshot response, but I am trying to think why we need this in the request.

@mdzraf mdzraf Jul 1, 2026

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This was one of the approaches that was considered but decided against because it would be good to support SPs that allow for creating Snapshots with topologies that differ from the source volume amongst other reasons. There is a more detailed explanation in the Alternatives Section of the KEP

}

message CreateSnapshotResponse {
Expand Down Expand Up @@ -1288,6 +1309,20 @@ message Snapshot {
// If this message is inside a VolumeGroupSnapshot message, the value
// MUST be the same as the group_snapshot_id in that message.
string group_snapshot_id = 6;

// Specifies where (regions, zones, racks, etc.) the provisioned
// snapshot is accessible from.
// A plugin that returns this field MUST also set the
// SNAPSHOT_ACCESSIBILITY_CONSTRAINTS plugin capability.
// An SP MAY specify multiple topologies to indicate the snapshot is
// accessible from multiple locations.
// COs MAY use this information to ensure that a desired volume can
// be provisioned from a given snapshot when scheduling workloads.
// This field is OPTIONAL. If it is not specified, the CO MAY assume
// the snapshot is equally accessible from all topologies in the
// cluster and MAY provision volumes referencing the snapshot as a
// source without topology constraints.
repeated Topology accessible_topology = 7 [(alpha_field) = true];
}
message DeleteSnapshotRequest {
// The ID of the snapshot to be deleted.
Expand Down
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