Non-Admin user can filter their instances by more filters

https://blueprints.launchpad.net/nova/+spec/non-admin-filter-instance-by-az

Many instances filter are restricted to admin-only users, while the related attribute are readable when showing instance detail for non admin users.

In order to stay coherent, all existing instance filters that are related to a field readable by default to non admin users when showing instance details, should be allowed by default without policy modification.

Problem description

The following instance filters are restricted to admin-only users (they are ignored if provided by non admin), but the related attribute in server payload are by default visible when displaying server informations:

  • availability_zone

  • config_drive

  • key_name

  • created_at

  • launched_at

  • terminated_at

  • power_state

  • task_state

  • vm_state

  • progress

  • user_id

This list was made by listing all existing admin-only instance filters 1, extracting those where the related attribute is readable by default for non-admin users in the nova server show API 2.

This spec target only existing filters for nova list API and does not aim to add new one.

Use Cases

It can be disturbing for a regular user who make some automation againt nova API not to be able to filter its instances againt field he can consult without any policy modification from operators, especially if the filter exist but is qualified as admin-only.

By example, in a multiple availability zone deployment, it is a commonly shared cloud pattern that users create their resources in multiple AZs in order to get resilient in case of failure of one AZ.

Dealing with multiple availability zone can lead to complexity for the user, by example in case of cinder usage, you can disable the cross_az_attach option to restrict volume attachment to be same AZ as the instance. In that configuration, it can be really useful to the customer to be able to filter their instance by AZ, by example in a user interface use-case, to display only instance who can be attached to a given volume.

Proposed change

Add a new microversion to servers list APIs to enable these filters for non admin users.

As non admin filters are listed in the _get_server_search_options function in nova/api/openstack/compute/servers.py, it will only require to add previously described values in that list for the given microversion.

Microversion bump is required in this context because API consumers need to be able to discover whether they should expect this filter to work or not. The mechanism for discovering that is by seeing whether a particular microversion is supported, especially in this case where prior to this fix, we’ll silently ignore these filters and the consumer would have no good way of knowing whether it worked or not. Hence why it is a blueprint and not a bugfix.

Alternatives

Currently the only way to allow non admin users to use these filters is to edit the nova policy os_compute_api:servers:allow_all_filters, which can be really painful to maintain during upgrades and can cause security issue as you don’t want regular user to use filters like the hypervisor or node one.

Data model impact

None

REST API impact

A new microversion will be added as we change the behaviour of the API for non admin users, even if we don’t add or remove any parameter.

List API will no longer ignore query string parameter for the following filters for regular user:

  • availability_zone

  • config_drive

  • key_name

  • created_at

  • launched_at

  • terminated_at

  • power_state

  • task_state

  • vm_state

  • progress

  • user_id

GET /servers?availability_zone=az2
GET /servers/detail?availability_zone=az1
GET /servers/detail?key_name=my_key&config_drive=True

Security impact

None

Notifications impact

None

Other end user impact

Python client may add help to inform users this new filter. Add support for the these filters in python-novaclient for the ‘nova list’ command.

Performance Impact

None

Other deployer impact

None

Developer impact

None

Upgrade impact

None

Implementation

Assignee(s)

Primary assignee:

Victor Coutellier

Feature Liaison

Feature liaison:

Balazs Gibizer Ghanshyam Mann

Work Items

  • Add filters to the non-admin whitelisted instance filters

  • Add related test

  • Add support for these filters to the ‘nova list’ operation in novaclient

Dependencies

None

Testing

  • Add related unittest

  • Add related functional test

Documentation Impact

The nova API documentation will need to be updated to reflect the REST API changes, and adding microversion instructions.

History

Revisions

Release Name

Description

Ussuri

Introduced