We are especially interested in using Ambari on Oracle Solaris 11.3 x86/x64.
We do not currently support it.
You can find the supported OS here they change slightly with Automated vs. Manual install ( essentially Centos, RHEL, SLES, Ubuntu, Debian, and Oracle Linux and some Windows versions )
I hope you will understand that we are hardly in a position to talk about the future support plans on a forum but perhaps you want to contact a local hortonworks sales person. Product decisions get influenced by customer demand.
Ok, this sounds good! So there is a slight chance that Oracle Solaris might be supported in the future. ;-)
The reason behind my question is that I have been asked by one of my co-workers working at a faculty if I could move his virtual machine (non global zone) based on Oracle Solaris to one of the supported Linux distros so he could install Ambari. We currently do not support Linux at our computing center at the FernUniversität in Hagen - that's why I asked for Oracle Solaris support. :-)
Adding Oracle Solaris as another supported plattform shouldn't be so difficult by the way: most if not all of the needed packages are already available in the base repository. Additional packages are available via opencsw.org. Packages are easy to install - e.g. "pkg install jdk-8".
The documentation is very good -> http://docs.oracle.com/cd/E53394_01/index.html
About the FernUniversität in Hagen: https://en.wikipedia.org/wiki/University_of_Hagen (Germanys largest university).