Nomad volume specification topology_request block

Specify locations such as region, zone, and rack, where a provisioned CSI volume must be accessible, or where an existing volume is accessible. The topology_request block is not supported for dynamic host volumes.

id           = "ebs_prod_db1"
namespace    = "default"
name         = "database"
type         = "csi"
plugin_id    = "ebs-prod"
capacity_max = "200G"
capacity_min = "100G"

topology_request {
  required {
    topology { segments { rack = "R2" } }
    topology { segments { rack = "R1", zone = "us-east-1a"} }
  }
  preferred {
    topology { segments { rack = "R1", zone = "us-east-1a"} }
  }
}

Consult the documentation for your storage provider and CSI plugin as to whether it supports defining topology and what values it expects for topology segments. Specifying topology segments that aren't supported by the storage provider may return an error or may be silently removed by the plugin.

Parameters

• required (Topology: nil) - On volume creation, the required topologies indicate that the volume must be created in a location accessible from at least one of the listed topologies. On volume registration the required topologies indicate that the volume was created in a location accessible from all the listed topologies.

• preferred (Topology: nil) - Indicate that you would prefer the storage provider to create the volume in one of the provided topologies. Only allowed on volume creation.

topology parameters

• segments (map[string]string) - A map of location types to their values. The specific fields required are defined by the CSI plugin.

Example

This example illustrates volume creation with preferred and required topologies. The configuration requires Nomad to create the volume within racks R1 or R2, but that you prefer creation within R1.

topology_request {
  required {
    topology { segments { rack = "R1", zone = "us-east-1a" } }
    topology { segments { rack = "R2", zone = "us-east-1a" } }
  }
  preferred {
    topology { segments { rack = "R1", zone = "us-east-1a"} }
  }
}