Add ‘protected’ filter to image-list call

Add ‘protected’ filter to image-list call

https://blueprints.launchpad.net/glance/+spec/add-protected-filter

Images contain a boolean ‘protected’ field. Filtering on this field in the image-list request is not currently supported. Operators and users who make use of the ‘protected’ field to prevent accidental deletion of images, however, would find such filtering useful. Not supporting filtering on this field is counterintuitive as Glance supports filtering on all other image fields.

Problem description

Use cases:

  • An End User wants to list protected images that are accessible to that end user.
  • An End User wants to list non-protected images that are accessible to that end user.

Proposed change

Add code so that when ‘protected=<value>’ is included in a query string on the image-list call, the value is converted to a boolean, making it suitable for database filtering (the ‘protected’ field is a boolean in the database backend).

For a user experience consistent with the image-create and image-update calls, the only accepted values for this parameter will be ‘true’ or ‘false’ in that exact case combination. Any other value for this parameter should return a 400 to indicate a bad request.

To summarize:

  1. Introduce a new query parameter to the GET v2/images call, namely, protected.
  2. The parameter will act as a filter on the ‘protected’ field of an Image.
  3. The set of values for the parameter will be strict, that is, the call will accept only those strings that satisfy the JSON boolean data type (in other words, only ‘true’ or ‘false’ in that exact case combination).
  4. Unrecognized values will result in a 400 (Bad Request) response with an appropriate message.
  5. When the protected query parameter is not present, no filtering will be done on the ‘protected’ field of Images. (In other words, there’s no default value.)

Alternatives

  1. Do nothing. This isn’t really an option, because even though ‘protected’ is not currently supported as a filter, image-list calls passing a value for ‘protected’ in the query string are accepted and do have an effect (the API behaves as if protected=False has been specified). This behavior appears weird to end users.

  2. Implement the filter, but accept a liberal set of values, recognizing, for example, ‘true’ or ‘false’ in any case combination; ‘yes’ or ‘no’ in any case combination; and 1 or 0. This can be accomplished by using the oslo string utilities, which contains a function bool_from_string that converts strings to an appropriate boolean value [APF-1]. Using the oslo library has an additional bonus in that the usage will be consistent across other OpenStack projects.

    The downside to this alternative is that it is inconsistent with the image-create and image-update calls in the Images v2 API. The latter calls are governed by the Image json-schema, which clearly specifies a JSON boolean type as the value of the protected field, and hence only ‘true’ or ‘false’ in that exact case combination is what these calls accept. Thus, liberal acceptance of commonly regarded boolean values in the query string may cause API users to be surprised when these liberal values don’t work for image-create or image-update, leading to user dissatisfaction.

  3. Implement the filter, but be extremely lax, that is, any value that isn’t mapped to the boolean value True by the oslo bool_from_string function would be considered False. This actually isn’t very user friendly. For example, a French language speaker applying the query filter ‘protected=oui’ will receive the complement of what was requested.

Data model impact

None

REST API impact

This is a very minor modification to the GET v2/images call. The only changes are:

  • Parameters which can be passed via the URL now include protected.

Security impact

None.

Notifications impact

None.

Other end user impact

The only impact on python-glanceclient is that the command

glance image-list --property protected=true

will now work correctly.

Performance Impact

None.

Other deployer impact

None.

Developer impact

None.

Implementation

Assignee(s)

Primary assignee:

  • fengzhr

Other contributors:

  • rosmaita
  • dharinic

Work Items

Dependencies

None.

Testing

Functional tests consistent with the current image-list filtering tests.

Documentation Impact

Small addition to the v2 image-list documentation in the api-ref.

Creative Commons Attribution 3.0 License

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