illumos

What became of opensolaris is now known as illumos and there are quite a few specialized illumos distributions around like SmartOS, OmniOS, OpenIndiana, Nexenta Stor and a few more.

FreeBSD and illumos are not Linux, but their still Unix-like, it's not like you'd have to use OpenVMS.

At least for illumos (SmartOS and OmniOS,...) there is a lot of work happening for web services.

As an example of the adventures of a relative newcomer to illumos, see the excellent writings of Ryan Zezeski, e.g.

What's the status on that, and can one build the compiler on Solaris/illumos, NetBSD and OpenBSD?

When the great split first occurred, I was really concerned that the Illumos path would die on the vine.

After oracle went closed again many assumed opensolaris died, but in fact a lot of interesting systems development is happening in illumos land.

And on illumos now you can even run Linux binaries in a zone.

They let you natively execute Linux binaries on any IllumOS-based operating system.

Most illumos-based operating systems (like OpenIndiana and SmartOS) will likely be more receptive to Let's Encrypt, though their desktop significance is also pretty low.

So the only place I've ever seen Illumos mentioned, it still seems like a niché product.

Considering its just a thin wrapper round samba and linux(or illumos, I can never remember), the support should be much better.

Those "lx" calls are compatible with the Linux system call table and get mapped and/or translated to illumos kernel system calls.

So yes, the fact that Linux is more widely used than FreeBSD and illumos in the developer community is certainly an important factor, but I don't see anyone ever saying "FreeBSD is great but we want to use something supported by a larger community", or "illumos is great, but we don't have expertise with it", which are certainly important arguments to consider when making a decision.

And now that illumos can run Linux inside a zone (and FreeBSD did this too 15 years ago, and still does for 32-bit binaries, I believe work is well underway to extend this to 64-bit as well), I think the "I only know Linux" argument loses some potency, you can run Linux after all...

Illumos zones are as lightweight as containers, can run Linux, and provide full isolation of the guest system.

The same should hold true of various OpenSolaris-based distributions such as Illumos, et al.

A promising direction imo is the more fine-grained permission model of Solaris/Illumos, which FreeBSD's Capsicum project also aims in the direction of.