The notion of Open Distro for ES being "a fork" is, in my opinion and as of last I checked, overblown. Yes, they bundle a bunch of freely licensed stuff to make up for features that Elastic themselves have paywalled off (or sealed behind their free-to-use, but non-libre, custom license where they don't show/include sources either), but they rely on and effectively install the (hitherto) Apache-licensed upstream release of ElasticSearch, as published by Elastic.
Also, if you take a closer look at Open Distro, you will quickly come to the conclusion that you really do not want to deploy what drops out of there. The RPM package does CRAZY stuff that made me exhale audibly enough for coworkers to notice - like spawning a postinstall shellscript that `wget`s a .so for/from an optional library that the Open Distro release team put into an S3 bucket, and then `mv`ing that downloaded file (iirc even without any content verification; so the content could be your proxy's captive portal markup, for all they know) into (again, iirc) /usr/lib. That is from WITHIN AN RPM PACKAGE, mind you, where you could and should really just carry that file yourself.
That and other minor troubles with the tooling surrounding the actual product (ES) made me abandon Open Distro fairly quickly. Which is a shame, since a really freely licensed spin of ES with "Enterprise" features would indeed be very nice to have.
TLS in enterprise settings is commonly intercepted by TLS/HTTPS proxies that create trusted (by the OS's local trust store) certificates for proxied peers on the fly. Banks often do this - the one I work for, for instance.
The McAfee-based proxy we have SOMETIMES (I guess it depends on the content-type and the length of the upstream response) renders a kind of "intermediate" HTML document as the response body, where the human user is supposed to click on a link that makes the UA download the originally requested resource from an internal, ad-hoc mirror. I guess that is due to some virus scanning snake oil.
At any rate, what the packages at Amazon did there is just right up in "that is crazy"-territory.
Though there's no confirmation I could find, there's an indication that they may/are:
Let’s take a quick look at the features that we are including in Open Distro for Elasticsearch. Some of these are currently available in Amazon Elasticsearch Service; others will become available in future updates.
Also, if you take a closer look at Open Distro, you will quickly come to the conclusion that you really do not want to deploy what drops out of there. The RPM package does CRAZY stuff that made me exhale audibly enough for coworkers to notice - like spawning a postinstall shellscript that `wget`s a .so for/from an optional library that the Open Distro release team put into an S3 bucket, and then `mv`ing that downloaded file (iirc even without any content verification; so the content could be your proxy's captive portal markup, for all they know) into (again, iirc) /usr/lib. That is from WITHIN AN RPM PACKAGE, mind you, where you could and should really just carry that file yourself.
That and other minor troubles with the tooling surrounding the actual product (ES) made me abandon Open Distro fairly quickly. Which is a shame, since a really freely licensed spin of ES with "Enterprise" features would indeed be very nice to have.