Arguably it goes back to chroot-stuff, and LXC predates Docker by some five years or so. I don't remember the details well but Solaris had similar containers, maybe even before LXC arrived.

I'd say the clown popularised it outside of Linux and Unix sysadmin circles, rather than the Dockerfile format itself.

> Arguably it goes back to chroot-stuff, and LXC predates Docker by some five years or so. I don't remember the details well but Solaris had similar containers, maybe even before LXC arrived.

Solaris and FreeBSD had significantly better implementations of the containerisation/isolation piece from a technical standpoint. But they never caught on. I really think the Dockerfile made the difference.