Quota Management and Enforcement

Neutron API中大多的resource都需要quota limits。

Neutron API暴露出一个extension 来管理quota，Quota limits are enforced at the API layer，

Plugin and ML2 drivers唯一例外是subnet_allocation[1] extension。

不支持per user and 多租户嵌套。

High Level View

主要组件：

• The Quota API extension;
• The Quota Engine.

quota driver：

• neutron.db.quota.driver.DbQuotaDriver
• neutron.quota.ConfDriver

The latter driver is however deprecated.

Quota Management

和其他Neutron extensions不同，它 有自己的own controller class [3].

其中_update_attributes只被调用一次，它会动态的更新Neutron’s resource attribute map [4]

driver operations包括：

• delete_tenant_quota, which simply removes all entries from the ‘quotas’ table for a given tenant identifier;
• update_quota_limit, which adds or updates an entry in the ‘quotas’ tenant for a given tenant identifier and a given resource name;
• _get_quotas, which fetches limits for a set of resource and a given tenant identifier
• _get_all_quotas, which behaves like _get_quotas, but for all tenants.

Resource Usage Info

• CountableResource
• TrackedResource

Quota Enforcement

• 通过count方法得到当前资源的usages.
• 通过 _get_tenant_quotas 得到租户的quota.
• usages减去expired reservations .
• 计算可用资源，与请求资源对比.

Setting up Resource Tracking for a Plugin

@resource_registry.tracked_resources(network=models_v2.Network,
port=models_v2.Port, subnet=models_v2.Subnet, subnetpool=models_v2.SubnetPool)

[1]	Subnet allocation extension:http://git.openstack.org/cgit/openstack/neutron/tree/neutron/extensions/subnetallocation.py

[2]	DB Quota driver class:http://git.openstack.org/cgit/openstack/neutron/tree/neutron/db/quota_db.py#n33

[3]	Quota API extension controller:http://git.openstack.org/cgit/openstack/neutron/tree/neutron/extensions/quotasv2.py#n40

[4]	Neutron resource attribute map:http://git.openstack.org/cgit/openstack/neutron/tree/neutron/api/v2/attributes.py#n639

[5]	Base controller class:http://git.openstack.org/cgit/openstack/neutron/tree/neutron/api/v2/base.py#n50

[6]	http://lists.openstack.org/pipermail/openstack-dev/2015-February/057534.html