Copyright 2020 Thierry Carrez This work is licensed under a Creative Commons Attribution 3.0 Unported License. http://creativecommons.org/licenses/by/3.0/legalcode
This document describes setting up a wiki farm based on Xwiki to serve the needs for lightweight, structured document publication (between etherpad and git-driven formal documentation) within Opendev communities.
Opendev serves multiple subcommunities. Some of them have expressed the need for a wiki: a lightweight way to publish information while retaining clear history and authorship. This is traditionally very helpful at early stages of the formation of communities.
Our current response is to ask them to set up pages on the Mediawiki instance on wiki.openstack.org. Beyond the obvious domain problem, this creates additional issues:
it increases our dependency on a difficult-to-maintain platform
it makes it hard to structure information or search within a given community scope
I evaluated various solutions. Xwiki emerged as a good candidate:
open source (although a bit open core)
limited maintenance costs, includes spam prevention tooling
“structured wiki” approach, which limits stale pages
pluggable into openstackID for authentication
support for subwikis (wikis with a root document and search context which live under the same main wiki domain) allowing each community to have what looks like a separate wiki
Xwiki.com, the company behind Xwiki, offers free hosting for open source communities. That offer is for the basic version of their cloud service. It includes up to 10 subwikis, unlimited users, 20Gb of storage, and limited tech support. They agreed to include usage of a custom domain, as well as manual configuration of OpenStackID authentication, although it would technically not be covered in the free hosting offer.
As a proof-of-concept, we propose to accept the free hosting offer and set up a wiki farm at wiki.opendev.org. Then we’d evaluate the software using a guinea pig community.
The OSF is helping bootstrapping the OpenInfra labs community (formerly known as Massachussets Open Cloud), a community of practice around operating OpenStack clouds for academic networks. That community is interested in using Opendev for project infrastructure, including Gerrit for managing code repositories. At those early stages they need a mailing-list (already set up at lists.opendev.org) and a wiki to share information.
The proposed plan is to create a subwiki for the Open Infra Labs community, and after some time evaluate how successful that setup is, before thinking about next steps (offer subwikis to other communities, hosting ourselves).
Doubling down on Mediawiki¶
We could host separate Mediawikis for each community under OpenDev, based on the puppet modules that we use to maintain wiki.openstack.org. However mediawiki has not been very pleasant to maintain, and we tried to reduce our exposure to it rather than increase it. Xwiki’s structured pages model also seems more adapted to our needs than Mediawiki’s flat model.
Gitea has a nice wiki feature (attached to specific repositories rather than specific communities). Since we are already using Gitea, it would make sense to enable that feature instead of relying on additional software.
However our gitea system is currently a set of independent setups, kept in sync via git pushes from gerrit. To enable the wiki feature, you need to be able to write to the git repos within gitea (and keep that consistent across the installation), which is still an unsolved problem at this point. Additionally, you need to enable user management and authentication support in Gitea, which is also an area nobody is planning to work on.
Direct Xwiki hosting¶
We could host Xwiki directly, rather than rely on Xwiki.com cloud hosting. That would have the benefit of not appearing to endorse an open core company, and keep our data and access log under our direct control. However, the open core model followed by Xwiki.com relies on a relatively sane demarcation between xwiki code and “pro” plugins, and Xwiki.com being a French company, they have to abide to pretty drastic data collection, retention and communication laws. Overall, the benefits of being able to outsource hosting and maintenance of the platform, as well as the immediate availability of the solution, justifies the positive trade-off.
Shall the proof-of-concept be successful, or shall we ever exceed the 10-subwiki limit, we would consider self-hosting the solution. Usage of a custom domain reduced the impact of a future transition.
Opendev did not make a clear decision on single-sign-on. As such, wiki.opendev.org would be set up with OpenStackID integration to avoid creating another set of crednetials, or increasing our UbuntuOne technical debt. Should we migrate to another SSO solution in the future, accounts for the proof-of-concept can easily be recreated if that ends up being necessary.
However this issue should be tackled before we expand to other subwikis, and certainly before we ever consider moving wiki.openstack.org content.
It is unclear at this moment how SSL certificate would be handled for wiki.opendev.org. This should be clarified with Xwiki support as we set up the instance.
- Primary assignee:
Use Gerrit topic “xwiki-farm” for all patches related to this spec.
git-review -t xwiki-farm
Set up main instance with OpenStackID integration, SSL.
Set up openinfralabs subwiki and open it up in that community
Evaluate after a few months of usage
wiki.opendev.org will have to be created a point to wherever XWiki.com asks us to point.
Documentation of the wiki set up should be added.
Wiki is isolated from the rest of opendev systems. We should make sure we do not accidentally leak profile information (by default Xwiki lists email addresses and OIDC addresses in the autogenarted profile page, this needs to be disabled).