glance-specs/specs/pike/approved/glance/lite-specs.rst

Glance Spec Lite

Please keep this template section in place and add your own copy of it between the markers. Please fill only one Spec Lite per commit.

<Title of your Spec Lite>

problem

<What is the driver to make the change.>

solution

<High level description what needs to get done. For example: "We need to add client function X.Y.Z to interact with new server functionality Z".>

impacts

<All possible *Impact flags (same as in commit messages) or 'None'.>

Optionals (please remove this line and fill or remove the rest until End of Template):

how

<More technical details than the high level overview of solution if needed.>

alternatives

<Any alternative approaches that might be worth of bringing to discussion.>

timeline

<Estimation of the time needed to complete the work.>

link

<Link to the change in gerrit that already would provide the solution. After commiting the Spec Lite depend the change to the Spec Lite commit.>

reviewers

<If reviewers has been agreed for the functionality, list them here.>

assignee

<If known, list who is going to work on the feature implementation here>

End of Template

Community Goal: Support Python 3.5

problem

Satisfy the Pike community goal Support Python 3.5

solution

Ensure that Glance meets the criteria of the Goal.

impacts

None.

assignee

Open

End of Community Goal: Support Python 3.5

Community Goal: Control Plane API endpoints deployment via WSGI

problem

Implement the Pike community goal Control Plane API endpoints deployment via WSGI.

solution

Implement a devstack plugin to run the Images API v2 supplied by Glance in mod_wsgi.

impacts

None.

assignee

Matt Treinish

End of Community Goal: Control Plane API endpoints deployment via WSGI

Introduce db sync --check feature

problem

It is very hard for automation of deploy and upgrade operations to know if there are db migrations pending. It requires the automation to know what the latest version is, and compare that to the output of a command to check the current version, then interpret the potential difference somehow.

solution

Similar to the linked feature added to Keystone's manage command, Glance should support an operation which enumerates any outstanding db upgrade operations and provide a distinct return code based on that status. Each expand, migrate, and contract operation required to upgrade the db should be listed in the proper order of execution in the response. For consistency with Keystone, this may be implemented by using a --check option. When this option is present no db upgrades would be performed but potential operations would be reported, acting similar to the pattern of a dry-run.

impacts

Introduces new option to the db sync operation in glance-manage.

timeline

Expected to be merged within the Pike time frame.

link

https://bugs.launchpad.net/keystone/+bug/1642212

assignee

Open

End of Introduce db sync --check feature

Introduce Glance Taskflow stopfile feature

problem

When preparing to take a Glance node down for maintenance or upgrade it is necessary to allow long-running operations to complete without allowing new operations to begin. The Taskflow engine does not have the capability to prevent individual executors from starting new jobs, and so attempting to take a Glance node out of the Taskflow processing pool risks a race condition with that executor starting a job just before the service is terminated which could cause the Task processing to fail.

solution

Introduce a disable_by_file_path feature to Glance Taskflow which will prevent the node from picking up new jobs. This allows an operator or automation engine to touch the appropriate file before terminating the service. This feature should depend on the oslo healthcheck middleware configuration to disable the taskflow engine. As an additional impact, this work will require Glance to instantiate a single taskflow engine as a singleton and reuse that engine instance on all subsequent taskflow operations.

impacts

None

timeline

Expected to have a fix merged in the Pike cycle before milestone 2.

link

https://docs.openstack.org/developer/oslo.middleware/healthcheck_plugins.html

assignee

Open

End of Introduce Glance Taskflow stopfile feature

Add your Spec Lite before this line