CreateVM supports subnet specified

CreateVM supports subnet specified

https://blueprints.launchpad.net/nova/+spec/selecting-subnet-when-creating-vm

Currently the network info specified as part of server creation is limited to network-id, port-id, and ip address. When a network has multiple subnets then we need to also be able to specify a subnet-id.

Problem description

Currently the network info specified as part of server creation is limited to network-id, port-id, and ip address.

So if an network has multiple subnets in it, it’s impossible to select which of the possible subnets a VM should be created in. You only could choose an ip address in one subnet and then create an instance. But this is not a convenient way. Moreover, this method is also not available for bulk instances creation.

Proposed change

  1. Add one optional param ‘subnet-id’ in networking structure of ‘spawn’.

  2. This parameter will affect in ‘allocate_for_instance()’ in nova/network/neutronv2/api.py.

  3. Bulk instances creation with ‘subnet-id’ will be supported, as the ‘net-uuid’ is specified.

Alternatives

None

Data model impact

None

REST API impact

The new ‘spawn’ rest API in v2::

/v2/{project_id}/servers

{

‘server’:{ … ‘networks’: [ { ‘subnet-id’: ‘892b9731-044a-4c87-b003-1e75869028c0’ } … ] … }

}

and in v3 it is like::

/v3/servers

{

‘server’:{ … ‘networks’: [ { ‘subnet-id’: ‘892b9731-044a-4c87-b003-1e75869028c0’ } … ] … }

}

  • Here, the <string> ‘subnet-id’ means the subnet your instances want to be created in. No default value.

  • If ‘subnet-id’ is not a string or uuid-like, a BadRequest exception will be raised.(HTTP 400)

  • The status code will be HTTP 202 when the request succeeded as usual, and the response body won’t be changed.

In the current implement in Nova, the network info specified is limited to network-id, port-id, and ip address, and port-id has the highest priority. So, we also need to point the priority during server creation.

  • The ‘port’ parameter still has the highest priority here.

    That means, if both ‘port’ & ‘subnet-id’ are specified, ‘port’ will be used and the ‘subnet-id’ won’t effect here.

  • The ‘subnet-id’ has the same priority with ‘v4-fixed-ip’/’v6-fixed-ip’.

    That means, if both ‘subnet-id’ & ‘v4-fixed-ip’/’v6-fixed-ip’ are specified, compatibility validation of these two arguments will be executed. * If it passed, the ip address you assigned will be used as usual. * If not, a BadRequest exception will be raised.(HTTP 400)

  • The ‘net-uuid’ parameter still has the lowest priority like before.

    That means, if both ‘subnet-id’ & ‘net-id’ are specified, ‘subnet-id’ will effect here and ‘net-uuid’ will be ignored like port specified.

Security impact

None

Notifications impact

None

Other end user impact

The related works in python-novaclient will also be added. After this modification, user could create instances with ‘subnet-id’ specified like ‘net-uuid’ does via CLI.

Performance Impact

None

Other deployer impact

None

Developer impact

None

Implementation

Assignee(s)

Assignee: wingwj <wingwj@gmail.com>

Work Items

In nova:

  • Add ‘subnet-id’ to ‘create’ in API layer

  • Use ‘subnet-id’ for ‘allocate_for_instance()’ in nova/network/neutronv2/api.py

  • Add related tests both API & nova-compute

In python-novaclient:

  • Add ‘subnet-id’ support in python-novaclient

  • Add related tests in python-novaclient

In tempest:

  • Related test-cases will definitely be added here

In doc:

  • The API modification will also be registered in openstack-doc

Dependencies

None

Testing

The unit tests need to be added in each related projects like I described in <Work Items> part. After the modifications, all changed methods above will be verified together.

Documentation Impact

The ‘server creation’ in API & CLI documentations will need to be updated to:

  • Reflect the new ‘subnet-id’ parameter and explain its usage

  • Explain the priority of network info during server creation

References

None

Creative Commons Attribution 3.0 License

Except where otherwise noted, this document is licensed under Creative Commons Attribution 3.0 License. See all OpenStack Legal Documents.

nova-specs