Provision to append the new metadef-tags with the existing metadef-tags

In the Glance API we are not having the provision to append the new metadef-tags with the existing metadef-tags. Introducing a new optional parameter would help the user to select whether to append the tags or to go with current behaviour i.e. overwrite the existing tags.

Problem description

Our md-tag-create-multiple (POST /v2/metadefs/namespaces/{namespace_name}/tags) API overwrites existing tags for specified namespace rather than creating new one in addition to the existing tags. Whereas if you try to create different tags using md-tag-create (POST /v2/metadefs/namespaces/{namespace_name}/tags/{tag_name}) it is adding new tag in addition to existing ones. So we should have consistency between the two APIs i.e. the ability to append the tags in md-tag-create-multiple API.

Proposed change

At the moment the glance API only overwrites the existing tags with the newly created tags i.e. the original/default behaviour. The new behaviour suggests to append the new tags with the existing ones. The goal is to provide an optional header X-Openstack-Append that takes boolean values, which will default to the original behaviour. If not present, the behavior is the same as passing X-Openstack-Append: False.

If header is present then we are going to append new tags else keep the old behavior.

In addition to this we will add an optional parameter at glanceclient side which will default to the original behaviour and if the user wants to append the new tags it can be by changing the value of parameter to True.



Data model impact


REST API impact

We are going to change the API and will be adding a X-Openstack-Append in the header. The rest API look like this:

POST /v2/metadefs/namespaces/{namespace_name}/tags

Header fields:

  • The <boolean> ‘X-Openstack-Append’ is an optional header, refers to appending the tags to the existing tags. It takes boolean values if True then it will append the tags ,if False it will overwrite the tags, default value is False.

Example curl usage:

curl -i -X POST -H "X-Auth-Token: $token" -H "X-Openstack-Append: False"
-H "Content-Type: application/json"
-d '{"tags": [{"name": "sample1"}, {"name": "sample2"}]}'

Security impact


Notifications impact


Other end user impact

We will add an optional parameter --append to the glanceclient command md-tag-create-multiple to provide the facility of appending the tags. If the parameter is present then it will the append the tags to existing ones else will overwrite the existing tags.

  • Create multiple tags: glance md-tag-create-multiple <NAMESPACE> --names <NAMES> [--delim <DELIM>] --append

Performance Impact


Other deployer impact


Developer impact




Primary assignee:


Other contributors:


Work Items

  • Add a boolean parameter in the header and change API functionality as per parameter’s value

  • Add an optional parameter --append at the client side

  • Add unit test coverage for checking the functionality.

  • Add tempest test




We will provide unit tests coverage for testing the functionality based on the header.

Documentation Impact

The documentation needs to be updated with the new API behaviour.