Devstack external plugins

https://blueprints.launchpad.net/tempest/+spec/devstack-external-plugins

Support external plugins for devstack.

Problem description

Devstack has a pretty strong plugin support, you just have to drop your extra feature in the extras.d/ directory and it will automatically parse the file and install the feature as long you have enabled it in your local.conf.

This all works very well but that’s not very flexible for projects that are not able to be integrated directly in devstack core. Currently an external OpenStack project who wants to tell its users how to test a feature has to explain how to download a file to put in the extras.d directory and enabling it.

As for integrated projects they may wants to take care of how they do devstack directly in their own repo and get devstack to use that instead of having to request for a change in devstack repository.

Proposed change

Devstack would provide a new enable_plugin function call that would be of the following format:

enable_plugin <name> <http://git.openstack.org/foo/external_feature>
[refname]

name is an arbitrary name picked for enablement, repo is the full url to a git repo, and refname is the optional ref description (defaulting to master if none is provided).

Devstack would then checkout that repository in ${DEST}/name and look for a /devstack/ directory in there from the root of the repo.

Files in there would have :

  • /devstack/settings - a file that gets sourced to override global settings, those variables become instantly available in the global namespace.

  • /devstack/plugin.sh - dispatcher for the various phases

Devstack when executed will then:

  • Get the configuration of the extras.d repos.

  • Clone the extras repository to ${DEST}

  • Run all the extras.d scripts at a particular phase

  • Run all the plugins plugin.sh at a particular phase

This would let the out of tree projects that needs to communicate about their config to export data via settings that would let the other configure based on their setup.

Alternatives

The alternative would be to stay as the status quo like we have now and have them to curl the extras file from the external repository and place it in the extras.d directory.

Implementation

Assignee(s)

Primary assignee:
Other contributors:

Milestones

Target Milestone for completion:

Kilo-2

Work Items

  • Add support in devstack.

  • Get an example repository setup.

  • Get a project like nova-docker to use it. * (glusterfs is a good current candidate)