Reload filesystem_store_datadirs configuration without service restart

Registered by Abhishek Kekane on 2014-04-21

In production environment, when the storage is almost full administrator will add more capacity by adding more disks, then modify the glance-api.conf and finally he/she would want to reload the configuration changes without restarting service as restarting service would break users connected to it abruptly.

For example
filesystem_store_datadirs = /x/glance/images:1
changed to
filesystem_store_datadirs = /x/glance/images:1, /y/glance/images:1

will be allowed.

But if you try to remove the existing entries, then it will give error with proper error message and continue to run with the previous configuration values.

filesystem_store_datadirs = /X/glance/images:1
changed to
filesystem_store_datadirs = /A/glance/images:1, /Y/glance/images:1

will not be allowed as users won’t be able to retrieve images stored at
/X/glance/images path.

Note:
We are depending on existing support here
https://blueprints.launchpad.net/nova/+spec/config-reload-no-restart
John Garbutt from Nova is working on above mentioned blueprint,
where he is making changes to oslo librabry for adding
"can_update_without_restart" and "update_without_restart=True"
options.
So once the above changes are in we will start implementation to address our change.

Blueprint information

Status:
Complete
Approver:
None
Priority:
High
Drafter:
Abhishek Kekane
Direction:
Needs approval
Assignee:
Abhishek Kekane
Definition:
Superseded
Series goal:
None
Implementation:
Unknown
Milestone target:
None
Completed by
Nikhil Komawar on 2015-03-05

Related branches

Sprints

Whiteboard

nikhil_k: update 2015-03-05:
superseded by https://blueprints.launchpad.net/glance/+spec/sighup-conf-reload

This basic idea sounds great. I think the fs store is a great place to start trying out reconfigurations.
However, I cannot find any real activity in oslo or nova around the dependency for this feature. Did I miss something? The blueprint linked in the description seems semi-abandoned and there is no related nova-specs entry that I could find. And if we do find an active blueprint, we probably need it to be targeted before we can accept this proposal.
markwash more-info 2014-04-25

Hi Mark,

I have added new blueprint in oslo for the dependency of this feature, and updated the dependency tree as well.

abhishek

Gerrit topic: https://review.openstack.org/#q,topic:bp/glance-config-reload-without-restart,n,z

Addressed by: https://review.openstack.org/122181
    Zero downtime configuration reload

Gerrit topic: https://review.openstack.org/#q,topic:zero-downtime-config-reload-patch2,n,z

Gerrit topic: https://review.openstack.org/#q,topic:zero-downtime-config-reload-patch3,n,z

(?)

Work Items

Dependency tree

* Blueprints in grey have been implemented.

This blueprint contains Public information 
Everyone can see this information.