cinder-specs/specs/liberty/get-vol-type-extra-specs.rst

Retrieve Supported Volume Type Extra Specs

https://blueprints.launchpad.net/cinder/+spec/get-volume-type-extra-specs

The purpose of this spec is to modify the driver's get_volume_stats method to include in its return value a dictionary of volume type extra spec keys that each driver supports. The dictionary will be used to improve the volume types extra spec management process in Horizon.

Problem description

The current implementation of volume type extra specs management process in Horizon is error-prone. Administrators must manage extra specs without having any interactive guidance on what possible keys are available and what their values are. Having the ability to obtain the permissible volume type extra specs while creating or editing the extra specs will make this task easier and more user-friendly.

Use Cases

Proposed change

The driver's get_volume_stats method will be modified to also return a dictionary of supported volume type extra spec keys. The dictionary will include information about those keys such as key description, possible values, value range, and value type. Once the get_volume_stats() method was modified, Horizon could call the existing scheduler_stats API call to get the dictionary and use it in the extra specs creating or editing process. The new extra_specs dictionary will be included within the existing capabilities dictionary:

Current json response of the scheduler_stats API call:

{
  "pools": [
    {
      "name": "ubuntu@lvm#backend_name",
      "capabilities": {
        "pool_name": "backend_name",
        "QoS_support": false,
        "location_info": "LVMVolumeDriver:ubuntu:stack-volumes:default:0",
        "timestamp": "2014-11-21T18:15:28.141161",
        "allocated_capacity_gb": 0,
        "volume_backend_name": "backend_name",
        "free_capacity_gb": 7.01,
        "driver_version": "2.0.0",
        "total_capacity_gb": 10.01,
        "reserved_percentage": 0,
        "vendor_name": "Open Source",
        "storage_protocol": "iSCSI"
      }
    }
  ]
}

New json response of the scheduler_stats API call:

{
  "pools": [
    {
      "name": "ubuntu@lvm#backend_name",
      "capabilities": {
        "QoS_support": false,
        "allocated_capacity_gb": 0,
        "driver_version": "2.0.0",
        "free_capacity_gb": 7.01,
        "location_info": "LVMVolumeDriver:ubuntu:stack-volumes:default:0",
        "pool_name": "backend_name",
        "reserved_percentage": 0,
        "storage_protocol": "iSCSI",
        "timestamp": "2014-11-21T18:15:28.141161",
        "total_capacity_gb": 10.01,
        "vendor_name": "Open Source",
        "volume_backend_name": "backend_name",
        "extra_specs": [
          {
            "description": "HP 3PAR Fibre Channel driver",
            "display_name": "HP3PARFCDriver",
            "namespace": "OS::Cinder::HP3PARFCDriver",
            "properties": {
              "hp3par:persona": {
                "default": "2",
                "description": "HP 3PAR Persona",
                "enum": {
                  "1": "Generic",
                  "10": "ONTAP-legacy",
                  "11": "VMware",
                  "12": "OpenVMS",
                  "13": "HPUX",
                  "15": "WindowsServer",
                  "2": "Generic-ALUA",
                  "6": "Generic-legacy",
                  "7": "HPUX-legacy",
                  "8": "AIX-legacy",
                  "9": "EGENERA"
                },
                "title": "persona",
                "type": "string"
              },
              "hp3par:snap_cpg": {
                "description": "Overrides the 'hp3par_snap' setting",
                "title": "snap_cpg",
                "type": "string"
              }
            }
          },
          {
            "description": "HP LeftHand iSCSI driver",
            "display_name": "HPLeftHandISCSIDriver",
            "namespace": "OS::Cinder::HPLeftHandISCSIDriver",
            "properties": {
              "hplh:provisioning": {
                "default": "thin",
                "description": "Provisioning",
                "enum": [
                  "full",
                  "thin"
                ],
                "title": "provisioning",
                "type": "string"
              },
              "hplh:vvs": {
                "default": "1",
                "description": "VVS",
                "title": "vvs",
                "type": "integer"
              }
            }
          }
        ]
      }
    }
  ]
}

The properties attributes are defined using simple JSON schema notation. Please refer to the JSON Schema documentation for a complete definition.

Alternatives

The alternative of this proposal is the current Horizon process of managing the volume type extra specs which does not provide any helpful information to administrators regarding possible extra specs keys and values. They have to know the exact spellings of the key/value pair that they want to set for each volume type ahead of time. Most of the time they have to look through the driver documentation or even the code to see what keys could be used in their situation.

Data model impact

None

REST API impact

None

Security impact

None

Notifications impact

None

Other end user impact

Horizon will be updated to include the displaying of the supported extra spec keys so users can select and set the values while creating or editing the volume type extra specs. Horizon will use the information about each key to set constraints for the value input field, which will help to screen out invalid values at a certain level.

If the volume type does not have any volume backend name associated with it, Horizon will not have any extra specs keys to display. Administrators can still enter in key/value pairs of their own. This is the same behavior as the current process.

If a driver does not publish the extra_specs dictionary, which will be the case for any drivers that do not get updated, then no client-side filtering will be performed, and the behavior will basically revert to the current situation where the administrator in horizon will need to know and enter the key/value pairs without any additional guidance.

Performance Impact

None

Other deployer impact

None

Developer impact

Driver developers will need to add a dictionary of volume type extra spec keys that their drivers support to the return value of the get_volume_stats() method. The dictionary will contain information about the keys as mentioned in the proposed change section.

It is completely up to the driver to decide how much information about its extra spec keys to provide in the dictionary. The driver can also choose not to provide any extra spec key at all, which means that there would be no extra specs for that particular driver to display in Horizon. But administrators would still be able to enter in key/value pairs of their own. This is the same behavior as the current process.

Implementation

Assignee(s)

Primary assignee:

jgravel (julie.gravel@hp.com)

Other contributors:

gary-smith (gary.w.smith@hp.com)

Work Items

• Add extra specs dictionary to all supported drivers' get_volume_stats method

Dependencies

Horizon blueprint that will depend on this spec:

• https://blueprints.launchpad.net/horizon/+spec/vol-type-extra-specs-describe

Testing

Unit tests for all changed files

Documentation Impact

None

References

JSON Schema documentation