According to their blogpost (https://www.elastic.co/blog/licensing-change):
> Starting with the upcoming Elastic 7.11 release, we will be moving the Apache 2.0-licensed code of Elasticsearch and Kibana to be dual licensed under SSPL and the Elastic License, giving users the choice of which license to apply.
Their //FAQ on 2021 License Change// : https://www.elastic.co/pricing/faq/licensing
Considering this is happening:
1. WIll CirrusSearch rely on ElasticSearch in the near future (say on version 7.x)?
2. Will CirrusSearch rely on ElasticSearch in long-term?
3. According to task T213996, the switch from MongoDB had happened because it was removed in Debian and therefore will be unsuitable for long-term use., and therefore it was unclear if a precedent was achieved. Are there any policy change or clarification if another dependency announced to switch to a license that may not be suitable for MediaWiki?
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Context on proprietary relicensing:
https://sfconservancy.org/blog/2020/jan/06/copyleft-equality/
Existing alternative venues:
https://opendistro.github.io/for-elasticsearch/contribute.html ("distribution" or "fork" depending who you ask, no CLA)
Some announced forks:
https://aws.amazon.com/blogs/opensource/stepping-up-for-a-truly-open-source-elasticsearch/
https://logz.io/blog/open-source-elasticsearch-doubling-down/