Last year Elastic opened up the source code of their commercial X-Pack offering: https://www.elastic.co/blog/doubling-down-on-open. This means that these components (security, alerting, etc.) are now available in the GitHub repository, but they are covered by the proprietary Elastic license instead of the Apache 2.0 license like the rest of the software. Some of the proprietary parts can be used for free, some need a paid commercial subscription. None of them are true open source (free as in freedom), though.

However, this is also when Elastic started muddying the waters (to quote the AWS blog post). Most of the new features across the Elastic stack that were added in the past couple of months (Index Lifecycle Management, APM UI, Infrastructure and Logs UI, Kibana multi-tenancy, Kibana Canvas) are not added to the Apache 2.0 codebase but are only available in the free-but-not-open version. These features can be used for free with the Basic subscription (no registration needed) but only under the terms of the Elastic license.

And this Elastic license is where AWS feels the pain. It clearly prohibits SaaS offerings:

> You agree not to: [..] use Elastic Software Object Code for providing time-sharing services, any software-as-a-service, service bureau services or as part of an application services provider or other service offering (collectively, "SaaS Offering") [..]

(from https://github.com/elastic/elasticsearch/blob/6.6/licenses/E...)

The license is very similar to moves that MongoDB and Redis made recently. Only Elastic is just now doubling down on adding new (and highly demanded) features to their proprietary offering.