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+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+==================================
+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
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