History Samba 3 was a good and stable product that could replace windows NT4 file and print services. Then MS created Active Directory, for which of course the SAMBA project wanted to also create an alternative. After some unhappy communications with OpenLDAP team they decided to implement an own LDAP server but underestimated the effort. Thus only after many years they were able to produce a production ready solution. Now it is ready to use and the question is who is already doing respective migration projects.
Why migrate from MS AD to Samba?
Some user think that the interfaces provided by MS are good and easy to use and are happy with CALs
What happens with ADFS
OpenLDAP —+—-IdP—–[SAML]——ADFS(SP)–[WS-Fed]—SharePoint | | + [sambaLDAP]-Smaba-SMB
What would be needed is not only an alternative to AD but also to ADFS including WS-Fed. Client library for ADFS still uses WS-Fed
Shibboleth SP supports WS-FED: “The SP can act as a WS-Federation Passive Profile relying party in the same fashion that it supports SAML” https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPADFS
Other government wanted to analyse open source alternatives, but without replacing MS AD, you still needed CALs for every desktop
In general it is hard to replace MS infrastructures, since user expectation is that nothing should change user interface wise, e.g. migrate away from Exchange without outlook users